595 Sentences With "fenestra" | Random Sentence Generator

Fenestra are not found in all dinosaur skulls, but those that do have them include tyrannosaurs and pterosaurs.

Previously, these holes — called the dorsotemporal fenestra — were thought to be filled with muscles that helped operate the powerful jaw.

What the scientists can tell, based on this research, is that there are no osteological features on the skull of the tyrannosaurus that indicate the fenestra were sites of muscle attachment.

To start figuring out what these holes were for, the team analysed different diapsid skulls to determine which ones had fenestra most similar to T. rex; the closest similarities turned out to be with crocodilians.

They can also infer, based on modern alligators, that the fenestra could have been used to regulate temperature in the T. rex's skull, by warming or cooling the blood that flows through blood vessels in the structures.

The lateral temporal fenestra in relation to the other skull openings in the dinosaur Massospondylus. An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. An opening in front of the eye sockets, conversely, is called an antorbital fenestra. Both of these openings reduced the weight of the skull.

The antorbital fenestra itself only occupies 40% of the length of this depression. These fenestrae are augmented by a rather large promaxillary fenestra at the front of the antorbital fossa, similar to that of Archaeopteryx, as well as an additional smaller opening (an accessory fenestrae) slightly lower than the promaxillary fenestra, between it and the maxillary fenestra. The strut separating the maxillary fenestra from the antorbital fenestra is pierced by a connecting channel, a typical troödontid trait. The eye socket is longer than high.

Skull reconstruction There were three teeth in the premaxilla, in contrast to Herrerasaurus (which possessed four). The contact between the premaxilla and maxilla encompassed two fenestrae (holes): a subnarial fenestra which was situated low on the snout and an additional smaller fenestra positioned above it. While a subnarial fenestra is common in herrerasaurids and theropods, the additional fenestra is unique to Gnathovorax. Like other archosaurs, a small basin known as the antorbital fossa is present in front of the antorbital fenestra.

It is however doubtful that all anapsids lack temporal fenestra as a primitive trait, and that all the groups traditionally seen as anapsids truly lacked fenestra.

In contrast to other Osteolepiformes, which similarly possess a posterior supraorbital bone that extends ventrally along the orbital fenestra, the contact with the lachrymal by the posterior supraorbital bone is a diagnostic character of Eusthenodon and results in the separation of the jugal and postorbital bones from meeting the orbital fenestra. The positions and relative sizes of additional fenestra present in Eusthenodon, including the fenestra exonarina, pineal foramen, and pineal fenestra are further diagnostic characters of the genus. The triangular pineal fenestra is well known in Eusthenodon for its large size and the distinctive posterior tail of the fenestra coming near or in-contact to the posterior frontal margin. On the contrary, the pineal foramen is much smaller in size and is positioned distinctively posterior both to the center of radiation of the frontal and the postorbital bone of the frontoethmoidal shield.

Neosauropods display a large opening in the skull located ventral to the antorbital fenestra, known as the preantorbital fenestra. This opening is differentially shaped among various species of neosauropods, and it has been proposed that the preanorbital fenestra is reduced or closes up completely in adult Camarasaurus, but is otherwise ubiquitous among neosauropods.

The anterior fenestra appears to have been entirely enclosed by the maxilla, and there were two rows of small pits below it. The back of the maxillary fenestra had a bony wall called the interfenestral bar, which separated it from the antorbital fenestra, as in Byronosaurus. The antorbital fenestra (the largest of the three openings, located in front of the orbit) was rectangular in side view, and the part of the maxilla below it was low and did not have small foramina, unlike the front part. The maxillary teeth were placed along most of the lower margin of the antorbital fenestra.

A massive open space (about a third the length of the skull) lies in the area between these two extensions. This hole is known as a lateral temporal fenestra. Reptiles of the group Diapsida are typically characterized by having two temporal fenestrae at the back of the skull: a lower one on the side of the skull (the lateral temporal fenestra) as well as a larger one on the top of the skull (the supratemporal fenestra). Vancleavea breaks away from this standard, as its supratemporal fenestra has completely closed up during evolution, leaving only the huge lateral temporal fenestra.

In the shoulder girdle, the clavicle is expanded and bears a notch on its interior edge, while the interclavicle bears an expansion on its front end. The scapulocoracoid bears a primary coracoid fenestra, but apparently not a secondary coracoid fenestra. Whether or not it has a scapular fenestra is unclear. On the pubis, the symphysis was rather thin.

However, the lower temporal fenestra was not completely enclosed from below. In most early diapsids, such as Petrolacosaurus and Youngina, the lower edge of the lower temporal fenestra is formed by a bony bar composed of the rear branch of the jugal and the forward branch of the quadratojugal bone. Yet Acerosodontosaurus has a short rear branch of the jugal, and is completely missing a quadratojugal, rendering the lower temporal fenestra incompletely enclosed. While many later diapsids also have an incomplete lower temporal fenestra, the only other "younginiform" with such a trait is Hovasaurus.

The snout slopes anteroventrally from the posterodorsal corner of the infratemporal fenestra to what is seemingly the maxillary-premaxillary contact and the infratemporal fenestra is dorsoventrally deep. In contrast, the orbit is subcircular, not quite as dorsoventrally tall as anteroposteriorly long, smaller than the infratemporal fenestra, and only visible in lateral view. The anterolateral sector of the left supratemporal fenestra is relatively well preserved and it is visible only in dorsal view. The skull's antorbital fossa is roughly triangular, with its base longer than the other two sides.

The postfrontal and supratemporal together form the border of the upper temporal fenestra, but unusually, the postorbital has no contact with this fenestra. Again, it is similar to Cymbospondylus and not to Shastasaurus or Mikadocephalus in this respect.

The parietal bones are not visible in side view. The supratemporal fenestra has a straight inner edge. A paraquadratic fenestra is lacking. A well-developed process is present on the underside of the jugal branch of the ectopterygoid.

The synapsids are distinguished by a single hole, known as the temporal fenestra, in the skull behind each eye. This schematic shows the skull viewed from the left side. The middle opening is the orbit of the eye; the opening to the right of it is the temporal fenestra. Synapsids evolved a temporal fenestra behind each eye orbit on the lateral surface of the skull.

The subsquamosal fenestra, an opening at the back of the skull determined by the shape of the squamosal bone, is large and the mastoid bone is perforated by a fenestra (opening).Weksler, 2006, pp. 38–39; Weksler et al., 2006, p.

Segmented skull, vertebrae and shoulder girdle bones Elachistosuchus was originally thought to be a pseudosuchian archosaur by Janensch (1949). Janensch diagnosed it among other pseudosuchians by its small body size, the lack of a specialized body plan, and the presence of a large posttemporal fenestra and what he believed to be an antorbital fenestra. Walker (1966) reinterpreted Elachistosuchus as a rhynchocephalian closely related to the only living genus Sphenodon (the tuatara), based on the long front portion of the jugal bone, the allegedly acrodont dentition, the large posttemporal fenestra, the absence of an external lower jaw fenestra, and a strongly twisted end of the humerus. Walker (1966) also argued that the antorbital fenestra identified by Janensch actually represented a damaged opening for the lacrimal canal.

It lacked a posterior process (lower rear prong), which meant that the lower temporal fenestra was open from below. Conversely, the ascending process (upper rear prong) was elongated, stretching above the lower temporal fenestra to contact the squamosal bone at the rear of the skull. This jugal-squamosal contact (unique to Boreopricea among early archosauromorphs) effectively barricades the postorbital bone from the edge of the lower temporal fenestra. The lower jaw was long and slender.

Besides the before mentioned fenestra, the parietals also have a "postparietal fenestra", something rarely seen outside of Dicraeosauridae. A triradiate postorbital bone is present in Europasaurus, which evolved as the fusion of the postfrontal and postosbital bone of more basal taxa. Between the anterior and ventrally projecting processes the postorbital forms the margin of the orbit, and between the posterior and ventral processes it borders the infratemporal fenestra. Skull of Massospondylus with fenestrae labelled.

The trapezoidal infratemporal fenestra is 1.5 times as long as it is wide in K. langenbergensis.

Fenestra is a genus of grasshoppers in the subfamily Gomphocerinae with species found in South America.

Restoration Shansisuchus is a large erythrosuchid distinguished from other members of the group by two characters: a tongue-and-groove articulation between the premaxilla and nasal bones of the skull and the presence of a subnarial fenestra. In Shansisuchus the premaxilla, a bone that makes up the front of the snout, projects backward and fits into a groove in the nasal, a bone that makes up the top of the snout. The subnarial fenestra is present between the external nares (nasal opening) and the antorbital fenestra, a hole in front of the eye socket. It is separated from the antorbital fenestra by a vertical projection of the maxilla bone.

Each dentary had space for about 14 teeth. The maxillary tooth rows of Brachiosaurus and Giraffatitan ended well in front of the antorbital fenestra (the opening in front of the orbit), whereas they ended just in front of and below the fenestra in Camarasaurus and Shunosaurus.

The teeth towards the rear of the lower jaw are serrated, unlike a number of basal troodontids. The tooth row of the maxilla terminates below the front margin of the antorbital fenestra, whereas it terminates further forward - below the rear of the maxillary fenestra - in Jinfengopteryx.

Within this area a smaller hollowing is located, closed at the inside, perhaps representing the fenestra promaxillaris, of which it has the usual position, or the fenestra maxillaris, the normal identity of a single opening. In the braincase, the channel of the nervus trigeminus, the fifth brain nerve, is not bifurcated. The palatine bone is pneumatised, as shown by the presence of a pneumatopore. In the lower jaw, the external mandibular fenestra is rather small for a basal tetanuran.

The toothed dentary bone had two rear prongs surrounding the mandibular fenestra. Unique to Turfanosuchus among gracilisuchids, the lower prong was much longer than the upper prong. This had the added effect of excluding the angular bone (which formed the rear lower edge of the jaw) from forming the lower border of the mandibular fenestra. The surangular, which forms the upper rear portion of the jaw (and the upper border of the mandibular fenestra), was large.

In Taoheodon, the reflected lamina is large and rounded, facing down and back from the mandibular fenestra.

The lower jaw bears a small external mandibular fenestra, another characteristic of archosauriforms and their closest relatives.

The snout of Archaeornithoides features a long antorbital fenestra, stretching over three quarters of the length of the maxilla. The maxilla bears at least eight teeth. These are small, conical and smooth, lacking wrinkles, serrations or carinae. The palatine bone seems to show the presence of a secondary fenestra.

Most of the skull is known. The laterally narrow and vertically deep skull is similar to that of Dimorphodon, with an enormous external naris (nostril) being the largest skull opening, and a large antorbital fenestra. Unlike most pterosaurs, the margin of the antorbital fenestra bears a remnant of an antorbital fossa. The skull roof has a median ridge as well as large ridges along the medial borders of the upper temporal fenestra that mark attachments for the muscle that closed the mandible.

As in related genera, the nasoantorbital fenestra was comparatively large; it was long and high, which was 71 percent of the skull length (excluding the crest). The lacrimal bone, which separated the orbit from the nasoantorbital fenestra, was vertically elongated and higher than the upper surface of the orbit (in contrast to the condition seen in pterodactyloids with smaller nasoantorbital fenestrae). The orbit was slender and compressed from front to back compared to Tupuxuara and tapejarids, but similar to some of them in being more than half the height of the nasoantorbital fenestra. The orbit was positioned lower than the upper margin of the nasoantorbital fenestra, and therefore very low on the skull.

Most notable is evidence of a deep recess that is just anterior to the fenestra ovalis, containing evidence of smooth muscle interactions with the skull. Such smooth muscle interactions have been interpreted to be indicative of the tympanum and give the implications that this recess, in conjunction with the fenestra ovalis, outline the origin of the ear in Thrinaxodon. This is a new synapomorphy as this physiology had arisen in Thrinaxodon and had been conserved through late Cynodontia. The stapes contained a heavy cartilage plug, which was fit into the sides of the fenestra ovalis; however, only one half of the articular end of the stapes was able to cover the fenestra ovalis.

The fenestra maxillaris is larger than the antorbital fenestra, the usually more extensive skull opening in the snout side. The branch of the jugal towards the postorbital is notched. The postorbital has a rear branch that is vertically expanded. The rear blade of the ilium is slender in side view.

The rear edge of the jugal branch of the ectopterygoid, in front of the infratemporal fenestra, is deeply grooved. The lower jaw has a large external mandibular fenestra. The foramen mylohyoideum is largely oriented to the front and below. The head of the thighbone is directed to the inside and below.

As in most oryzomyines, the subsquamosal fenestra, an opening at the back of the skull, is present.Weksler, 2006, pp.

Distinctly, the upper rear corner of the fenestra in Carnufex is situated above the lower rear corner, making the rear edge of the antorbital fenestra vertical rather than slanted forwards as in other early crocodylomorphs. The lacrimal is deeply incised by the antorbital fossa (the basin surrounding the antorbital fenestra). This fossa is rimmed by a rough ridge possessing a small but characteristic forward prong similar to that seen in some theropod dinosaurs. The outer surface of the jugal is also covered with pits and ridges.

The braincase is where Protoavis comes close to being as avian as Chatterjee has maintained. The otic capsule is allegedly organized in avian fashion, with three distinct foramina arranged as such: fenestra ovalis, fenestra pseudorotunda, and the caudal tympanic recess, with a bony metotic strut positioned between the fenestra pseudorotunda and caudal tympanic recess. The claim that the full complement of tympanic recesses seen in ornithurines, are similarly observed in Protoavis is questionable, as the preservation of the braincase is not adequate to permit concrete observations on the matter. Chatterjee omits in his 1987 account of the braincase, the presence of a substantial post-temporal fenestra, which in all Aves (including Archaeopteryx), is reduced or absent altogether, and the lack of a pneumatic sinus on the paroccipital.

The back margin of the fenestra slopes backwards, like LFGT LDM-L10 and Dilophosaurus but unlike KMV 8701. Further behind, the orbit is keyhole-shaped, with a longer back rim compared to the front rim. The infratemporal fenestra is roughly trapezoidal, with a long axis oriented upwards and backwards towards the top of the rear of the skull. On the top surface of the skull, the rounded supratemporal fenestra is unusually small, with a diameter equivalent to only about half of the length on the top of the skull behind the level of the orbit.

The ectopterygoid bones are three-pronged; the lateral processes close off the back of the suborbital fenestra, the anterior processes join the process of the palatal shelf, and the posterior process overlaps the pterygoid bone and forms part of the pterygo-ectopterygoid fenestra, which is separated from the suborbital fenestra by a bar of the pterygoid; the same bar is seen in Gnathosaurus, albeit much shorter. As for the pterygoid itself, it was expanded along the midline and projected backwards to connect to the basisphenoid bone and quadrate.

Dilipa fenestra is a butterfly found in the East Palearctic (East China, Northeast China, Korea) that belongs to the browns family.

The frontal forms a complex interdigitate joint with the postorbital from the dorsal rim of the orbit to the supratemporal fenestra.

Uniquely, the postfrontal does not border the supratemporal fenestra, but still forms a long process in contact with the supratemporal. The parietals touch the anteriomedial process of the supratemporals, another autapomorphy. This anteromedial process also blocks the postfrontal from bordering the supratemporal fenestra. The parietals are crushed against one another, but there is no evidence of a crest.

Their limbs were long, and skeleton built lightly suggests they were active and agile. A long low skull and dentition extended far back to lie below the temporal fenestra. Aerosaurus had other general features found in ‘Pelycosaurs’ like a slanted Occiput, a lateral temporal fenestra, a septomaxilla bone that contacting the nasal and a maxilla bone contacting the quadrojugal.

Euagra fenestra is a moth of the subfamily Arctiinae. It was described by Francis Walker in 1854. It is found in Brazil.

Fenestella is Latin, meaning little window, from fenestra "window", for the window-like openings in the mesh of the skeleton of its colonies.

Just above each jugal lies a triangular postorbital bone. The thin dorsal process of each postorbital forms part of the front edge of each upper temporal fenestra, a large and circular hole at the upper part of the back of the skull. The front edge of each postorbital contacts a moderately large postfrontal bone, which forms part of both the rear edge of the orbit and the front edge of the upper temporal fenestra. Behind the rear tip of each jugal lies a diamond-shaped squamosal bone, which forms the lower edge of the upper temporal fenestra.

The jugal is similar in form to that of Europasaurus Multiple jugals are known from Europasaurus, which are more similar in morphology to basal sauropodomorphs than other macronarians. It forms part of the border of the orbit, infratemporal fenestra and the bottom edge of the skull, but does not reach the antorbital fenestra. The posterior process of the jugal are very fragile and narrow, showing a bone scar from the articulation with the quadratojugal. There are two prominences projecting from the back of the jugal body, which diverge at 75º and form the bottom and front edges of the infratemporal fenestra.

The antorbital fenestra in relation to the other skull openings in the dinosaur Massospondylus. An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds still possess antorbital fenestrae, whereas crocodylians have lost them.

In theropod dinosaurs, the antorbital fenestra is the largest opening in the skull. Systematically, the presence of the antorbital fenestra is considered a synapomorphy that unites tetanuran theropods as a clade. In contrast, most ornithischian dinosaurs reduce and even close their antorbital fenestrae such as in hadrosaurs and the dinosaur genus Protoceratops. This closure distinguishes Protoceratops from other ceratopsian dinosaurs.

A rather stubby snout is suggested by the fact that the front branch of the maxilla was short. In the depression around the antorbital fenestra to the front, a smaller non-piercing hollowing can be seen that is probably homologous to the fenestra maxillaris. The maxilla bears thirteen teeth. The teeth are relatively large, with a crown length up to seven centimetres.

Like other proterochampsians, there is no contact between the lacrimal and nasal. More unusually, there is also no trace of an antorbital fenestra between the maxilla, nasal, and lacrimal. The only other early archosauriform known to lack an antorbital fenestra is Vancleavea. One autapomorphy (unique distinguishing feature) of Rugarhynchos is the presence of a thick diagonal ridge on the side of the snout.

In zoology, the trilobite Fenestraspis possessed extensive fenestrae in the posterior part of the body. In the paleognathae, there is an ilio–ischiatic fenestra.

The postorbital bar is almost vertical, with an oval cross-section. The quadratojugal is just behind the laterotemporal fenestra, and is slender and branched.

The crista interfenestralis is an anatomical feature, found in some reptiles, that divides the inner ear between the occipital recess and the vestibular fenestra.

A subnarial fenestra is present in a few other more derived archosauriforms such as some dinosaurs and pseudosuchians, but its morphology in Shansisuchus is unique.

Low, laterally raised bony ridges were present on the dorsolateral margin of the nasal and lacrimal bones in the skull, directly above the antorbital fenestra.

Like the 'long scales', the skeletal features of Longisquama are equally difficult to diagnose. As a result, Longisquama has been related by scientists to many different sauropsid groups. Sharov determined that it was a "pseudosuchian" (a "primitive" archosaur, but as an archosaur a relatively derived reptile) on the basis of two features: a mandibular fenestra and an antorbital fenestra. Sharov's original description also includes an elongate scapula.

In morphology, fenestrae are found in cancellous bones, particularly in the skull. In anatomy, the round window and oval window are also known as the fenestra rotunda and the fenestra ovalis. In microanatomy, fenestrae are found in endothelium of fenestrated capillaries, enabling the rapid exchange of molecules between the blood and surrounding tissue. The elastic layer of the tunica intima is a fenestrated membrane.

The maxillae are tall and laterally compressed, forming most of the borders of the antorbital fenestra (visible on the photo above). The palatal process extends anteroventrally and is very short. A ridge extending to form a suture with the palatine is present above the sixth, seventh and eighth dental alveoli. Small infraorbital foramina are located around the edge of the antorbital fenestra, near the teeth.

Longusunguis differs from all other known bohaiornithid Enantiornithes by possessing a combination of traits, some of which are autapomorphies, i.e. unique. The maxilla of Longusunguis possesses an accessory fenestra on the jugal process. This trait is unique among bohaiornithids, as only Zhouornis possesses such fenestra, however on the dorsal process. Its lacrimal bone shows an elongate excavation on the caudal margin of its descending ramus.

Skull material for Mandasuchus is limited to maxillae and part of a dentary. The maxilla is low, with an elongated antorbital fenestra and at least 12 tooth sockets separated by discrete interdental plates. The antorbital fenestra is surrounded by an inset basin, the antorbital fossa, as with other archosaurs. However, Mandasuchus has a restricted and weakly differentiated antorbital fossa compared to other loricatans and Ticinosuchus.

The shoulder girdle and limbs of PMoL-B00175 Caihong was a rather small dinosaur. Its length was estimated at , and its weight at . The describing authors indicated a number of unique derived traits, autapomorphies. In addition to the antorbital, maxillary, and promaxillary fenestrae (skull openings) present within the antorbital fossa, the maxilla is also pierced by an accessory fenestra which opens behind and below the promaxillary fenestra.

Feathering on different areas of PMoL-B00175 The skull of Caihong has a length of 67.6 millimetres. It is low and elongated (superficially similar to that of Velociraptor), only slightly shorter than the femur. The nostril is large and oval-shaped. The elliptical maxillary fenestra, an opening in front of the antorbital fenestra, is large and located in the middle of the antorbital fossa.

Additionally, the total length of the maxillary fenestra is more than half the distance between the anterior margins of the antorbital fossa and fenestra. Unlike the contemporaneous Tarbosaurus, Zhuchengtyrannus lacks a subcutaneous flange on the posterodorsal part of the jugal ramus of the maxilla, and a ventrally convex palatal shelf that covers the bulges of the roots of the rear teeth in medial view.

Because of their disarticulation, it is likely that the frontals never fused during growth, unlike in Camarasaurus. The frontals form a portion of the skull roof, articulating with other bones such as the nasals, parietals, prefrontals and postorbitals, and they are longer antero-posteriorly than they are wide, a unique character among a eusauropodan. Like in diplodocoids (Amargasaurus, Dicraeosaurus and Diplodocus), as well as Camarasaurus, the frontals are excluded from the frontoparietal fenestra (or parietal fenestra when frontals are excluded). The frontals are also excluded from the supratemporal fenestra margin (a widespread character in sauropods more derived than Shunosaurus), and they only have a small, unornamented participation in the orbit.

There is a postero-median process on the nuchal plate, and a pre-pineal fenestra in this species. The skull of the holotype is 8.5 cm long.

Comparison between the of Majungasaurus and a bird sauropodomorph Massospondylus, showing the main skull openings (), including the , the , the , the (here: lateral temporal fenestra), the , and the .

A skull opening, the maxillary fenestra, is relatively large and positioned right above another opening, the promaxillary fenestra, a condition not known from other species. Atrociraptor was by its describers assigned to the Velociraptorinae within a larger Dromaeosauridae. However, in 2009 Currie published a cladistic analysis showing Atrociraptor to be a member of the Saurornitholestinae.N.R. Longrich and P.J. Currie, 2009, "A microraptorine (Dinosauria-Dromaeosauridae) from the Late Cretaceous of North America".

This bone is considered key in the determination of general traits in cases in which the entire skull has not been found intact (for instance, as with dinosaurs in paleontology). In some dinosaur genera the jugal also forms part of the lower margin of either the antorbital fenestra or the infratemporal fenestra, or both. Most commonly, this bone articulates with the quadratojugal, the postorbital, the lacrimal, and the maxilla.Martin, A.J. (2006).

A lateral projection extends from it to partially cover the mandibular fenestra. At the posterior end the surangular is closer to cylindrical. The angular is medially excavated by the mandibular fenestra, and forms a vertical contact zone with the dentary; at the posterior end, it is vertically expanded upwards to form a narrow blade. The dentary carries three teeth on the preserved portion, which closely resemble those on the maxilla.

The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and the lungs have a single chamber and lack bronchi. The tuatara has a well-developed parietal eye on its forehead. Lizards have skulls with only one fenestra on each side, the lower bar of bone below the second fenestra having been lost.

The maxilla, which has a long front branch, bears fourteen teeth, as can be deduced from the tooth sockets: the teeth themselves have been lost. There is a small maxillary fenestra, which does not reach the edge of the antorbital depression and is located behind a promaxillary fenestra. The lacrimal bone has a distinctive rounded horn on top. The lower branch of the postorbital bone is transversely wide.

King, Susan, Silver End: a place to work and play In 1907, Crittall bought the so-called Fenestra joint patent from the German company Fenestra in Düsseldorf. In the same year, Crittall began to operate the Detroit Steel Product Co, the first steel window factory in the United States. During the First World War, Crittall's factories were used in munitions production, but postwar the company returned to steel window manufacture.

Skull and restoration The skull is lightly built and has a length of 326 millimetres. It is very elongated, being just 55 millimetres high at the back, and has an triangular profile. Almost half of its length is accounted for by a large skull opening, the fenestra nasoantorbitalis, a confluence of the original fenestra antorbitalis with the bony nostrils. In front of this opening a low and elongated snout is present.

A ventral border of the Meckelian fenestra of the lower jaw formed entirely from the splenial bone is a distinguishing feature of Oradectes found in no other diadectid.

The zygomatic arch is significant in evolutionary biology, as it is part of the structures derived from the ancestral single temporal fenestra of the synapsid ancestor of mammals.

A projection from the quadrate bone into the lateral temporal fenestra (opening behind the eye) gave this a reniform (kidney-shaped) outline. The foramen magnum (the large opening at the back of the braincase) was about half the breadth of the occipital condyle, which was itself cordiform (heart-shaped), and had a short neck and a groove on the side. Life restoration showing hypothetical feathers and crest-shape The mandible was slender and delicate at the front, but the articular region (where it connected with the skull) was massive, and the mandible was deep around the mandibular fenestra (an opening on its side). The mandibular fenestra was small in Dilophosaurus, compared to that of coelophysoids.

It encloses the from the front; Tralkasaurus is unique among abelisaurids in that front margin of the antorbital fenestra slopes forwards and upwards, instead of being vertical or sloping backwards. The antorbital fenestra creates on both the upward- projecting process of the maxilla and (atypically among abelisaurids) the inner surface of the bone; this condition is more similar to basal abelisauroids like Noasaurus and Masiakasaurus, as well as the Averostra. Deep neurovascular grooves extend downward from the bottom rim of the antorbital fenestra, which is unlike Carnotaurus, Ekrixinatosaurus, Majungasaurus, and Skorpiovenator but similar to Rugops. More typically, the ascending process tapers and becomes laminar (sheet-like) at the top, like Skorpiovenator, Carnotaurus, and Majungasaurus.

The head of Liaodactylus is slender and long, with a skull length of and a jaw length of . Out of this, the snout is 49.1% of total skull length, and the nasoantorbital fenestra (the fusion of the nostril and the antorbital fenestra, seen in all members of the Monofenestrata) is 31% of skull length. In more derived ctenochasmatids, the nasoantorbital fenestra is much smaller relative to the skull, being only 10-12% of skull length in Pterodaustro; the snout is also longer, being over 85% of skull length in Pterodaustro. Also shorter than other ctenochasmatids is the dentary symphysis, the fused portion of the lower jaw, which is only 30.5% of jaw length.

Weksler, 2006, p. 40 The subsquamosal fenestra, an opening at the back of the skull determined by the shape of the squamosal, is almost absent.Sánchez et al., 2001, p.

The lacrimal is located above their joint, enclosing the fossa that surrounds the antorbital fenestra. There is a ridge directed downwards and backwards on the side of the jugal, like in Zupaysaurus; this same ridge is horizontal in Sinosaurus and Dilophosaurus. The same is also true of the joint between the jugal and quadratojugal. The quadratojugal tapers to a point underneath the infratemporal fenestra, where it is joined at the back to the quadrate.

The holotype specimen of K. elysiae is a juvenile, as shown by unfused neural spines and would have stood about high at the hip. The adult size of Kayentavenator is unknown. The inclusion of a pubic fenestra is one of the characteristics that Gay uses to set Kayentavenator apart from the contemporaneous, and better known Dilophosaurus. As Dilophosaurus lacks a pubic fenestra as a subadult or an adult,Welles, S. P. (1984).

Built at the Isle of Bute, their building was disturbed by the war so the first boat was not delivered until 1946. Eventually eight hulls were constructed and seven of them raced for many years in Dublin Bay. List of Boats and their sail numbers: # Fenestra # Vandra (lost) # Euphanzel # Zephyra # Adastra # Harmony # Periwinkle # Arandora The original five were Euphanzel, Fenestra, Vandra, Zephra and Adastra. These were later joined by Harmony and Arandora.

The skull of Daliansaurus, which measures long, is proportionally larger than that of Mei. Daliansaurus also has a smaller nostril. The projection of the premaxilla above the nostril is flattened instead of rod-like like in Sinovenator, while another projection below the nostril is straight like Sinusonasus but unlike Sinovenator. There are two openings of the skull in front of the eyes: the teardrop-shaped premaxillary fenestra, and the large, oval antorbital fenestra.

From January 1993 to December 1994, he served as president of the Fenestra Corporation. From 1995 to 1996, he was a group executive at the Marmon Group and directed operations at Arzo, MD Tech, Micro-Aire, Oshkosh Door, and Fenestra. From 1996 to 1998, he served as the Regional Vice President of Operations in Asia for Getz Bros. & Co.. In 1998, he was appointed by the Marmon Group to oversee Stainless Industrial Companies.

In Acleistorhinus the supraoccipital is rather plate-like. The reduction in the overall size of the supraoccipital allows for the development of large post-termporal fenestra, a characteristic of Reptilia.

Other characteristics of the skull separate Tongtianlong from its contemporaries; for instance, the nostril is situated much higher than the antorbital fenestra, a trait seen otherwise only in Nemegtomaia and Rinchenia.

An opening between the nasal and the prefrontal bones in one hupehsuchian specimen (known as IVPP V3232) was initially interpreted as an antorbital fenestra, but is now thought to be an artifact caused by the damage of the surrounding bones during preservation. Its position is not indicative of a narial opening, either. More likely, the naris lies between the nasal and the maxilla in an area anterior to that of the supposed antorbital fenestra, although the preservation of this area in known specimens is too poor to prove definitively that it is the external naris and not an artifact of preservation, as is the case for the fenestra. Hupehsuchus nanchangensis The neck is relatively elongated and the cervical ribs are short.

A similar situation is visible in other gracilisuchids, which have a broad contact between the jugal and the lower branch of the squamosal. However, they did not retain the upper portion of the lower temporal fenestra, leaving only a small, triangular remnant of the lower temporal fenestra under the squamosal-jugal contact. Preserved portions of the palate (roof of the mouth) were generally similar to Euparkeria. One particular similarity is the presence of teeth on the pterygoid bone.

The high projection comprises much of the upper margin of the mandibular fenestra, an opening along the side of the jaw. The mandibular fenestra is longer and narrower than those of related archosauriforms such as Turfanosuchus, Euparkeria, and Ornithosuchus. At the back of the jaw is the retroarticular region, which extends backward from the jaw joint. On the dorsal surface of this region on the articular bone is a prominent ridge that is not seen in other archosauriforms.

It had a dip towards the font, which made the area by its base concave in profile. The underside of the premaxilla containing the alveoli (tooth sockets) was oval. The maxilla was shallow, and was depressed around the antorbital fenestra (a large opening in front of the eye), forming a recess that was rounded towards the front, and smoother than the rest of the maxilla. A foramen called the preantorbital fenestra opened into this recess at the front bend.

Illustration A number of characteristics of the skull can be used to distinguish Gracilisuchus. Its skull openings are relatively large, with the antorbital fenestra occupying 30-36% of the skull roof's length and the eye socket occupying 35-42% of the skull roof's length. Additionally, the supratemporal fenestra is, uniquely, wider than it is long. Within the eye socket, there is a sclerotic ring, and the ossicles (bony segments) comprising the ring contact but do not overlap each other.

The lower temporal fenestra is trapezoidal in shape, another characteristic previously on found in archosauriforms, while the upper temporal fenestrae are slender. Close up of the snout and teeth. A unique feature (autapomorphy) of Teyujagua is that the external mandibular fenestra is positioned unusually far forward on the lower jaw, directly beneath the eyes when the jaw is closed. The dentition is heterodont, bearing four small premaxillary teeth and a maximum of 15 larger maxillary teeth.

For example, the shape of the maxilla shows that aphanosaurs had an antorbital fenestra, a large hole on the snout just in front of the eyes. Coupled with an antorbital depression (a collapsed area of bone which surrounded the fenestra), these indicate that aphanosaurs belonged to the group Archosauria. A partially-erupted tooth was also preserved on the lower edge of the maxilla. This tooth was flattened from the sides, slightly curved backwards, and serrated along its front edge.

Restoration The lacrimal has a thick rugose ridge extending back from that on the nasal. Its lamellar part forms the posterodorsal border of the antorbital fenestra, and is articulated with the maxillae which form much of the rest of the borders. There is also a descending process of the lacrimal which forms most of the posterior border of the antorbital fenestra, with a noticeably striated ridge. This descending process would probably have contacted the jugal at its ventral end.

There is only a weak lacrimal process, like in most sauropods except Rapetosaurus. The nasal process is elongate and covers the anterior and ventral rim of the antorbital fenestra. This process extends about 120º from the horizontal tooth row. The base of the nasal process also forms the body of the lacrimal process, and at their divergence is the antorbital fenestra, similar in shape to those of Camarasaurus, Euhelopus, Abydosaurus and Giraffatitan, but about 1/2 taller proportionally.

However, there are some factors that complicate a rhamphorhynchine position. In particular, the pear-shaped infratemporal fenestra and the overall size of the antorbital fenestra are more similar to scaphognathines than rhamphorhynchines. Additionally, like more basal non- rhamphorhynchid pterosaurs, there is a half moon-shaped process of the premaxilla extending beneath the nostril. It is thus possible that Parapsicephalus represents a basal rhamphorhynchid that is not in either group, which is not unexpected given its temporal context.

The function of this unique trait is unknown. The praemaxilla bears four teeth. The maxilla bears thirteen teeth. The maxilla has a short depression around the lower front of the antorbital fenestra.

The internal tuberosity of the humeral proximal end is short. A large fenestra perforates the humeral deltopectoral crest. The humeral ulnar condyle is hypertrophied. The ulna is slightly longer than the humerus.

The lacrimal bone, which usually forms the rear edge of the antorbital fenestra, has also disappeared. Grooves cover the skull roof while foramina (tiny pores) coat the skull bones near the mouth.

The upper temporal fenestra is large and kidney-shaped. There are 17 cervical vertebrae and the cervical ribs have anterior processes. The maxillae of Dactylosaurus extended broadly up the side of the snout.

The skull of Teyujagua is exceptionally well preserved and almost complete, possessing several key features of the archosauriform skull. In total it measures approximately , with a long, broad and flattened snout. Teyujagua possesses a mosaic of characteristics intermediate between basal archosauromorphs and Archosauriformes. Primitive features include the absence of an antorbital fenestra and an open lower temporal bar, however like Archosauriformes it has serrated teeth and an exposed mandibular fenestra on the lower jaw, features previously only found in Archosauriformes.

Albanerpeton have ossified antotic pillars which sit in front of the otic capsules. Additionally, there are a pair of small, robust bony pedestals that are located ventrolaterally in front of the otic capsules, which likely served to brace the neurocranium against the palatal region and suspensorium. In Albanerpeton, the otic capsules themselves are moderately inflated with large, rhomboid-shaped fenestra vestibulli present on both capsules. These fenestra can be used to imply the presence of middle ear ossicles in Albanerpeton.

Thalattosaurus alexandrae Thalattosaurs are diapsid reptiles, meaning that they have temporal fenestrae, two holes in the head behind the orbit (eye socket). However, many thalattosaurs have a vestigial upper temporal fenestra which is slit-like, and some have it fully closed up by surrounding bones. Thalattosaurs lack a quadratojugal bone, leaving the lower temporal fenestra open from below. They also lack postparietal and tabular bones, while the squamosal bone is small, the supratemporal bone is extensive, and the quadrate bone is large.

The process on the maxilla usually indicates the presence of an antorbital fenestra in archosauriforms, but in Azendohsaurus this space is occupied by the lacrimal bone in front of the eyes. This is a unique arrangement unknown in other Triassic archosauromorphs, except for the related Shringasaurus. The orbits are almost entirely occupied by the large sclerotic rings, suggesting large eyes. The lower temporal fenestra is open at the bottom, separating the jugal and the quadratojugal bones (a primitive trait for archosauromorphs).

Maxillary teeth are serrated and knife-like, with the front edge being significantly convex and the rear side being slightly convex. The posterior process is low and circular in cross-section at the front but deepens and thins towards the rear, a change in shape unique to Carnufex among loricatans. It also supports a sharp ridge which terminates at the rear lower corner of the antorbital fenestra. The antorbital fenestra itself takes the form of a very large and elongated triangular hole.

The describing authors established some diagnostic traits. In the depression for a skull opening, the fenestra antorbitalis, to the front a second opening is present, a fenestra maxillaris, that occupies much of the front part of this depression. The teeth in the maxilla only on their rear edges have denticles which are very small and directed towards the point of the teeth. The neck vertebrae are mildly opisthocoelous: with centra that are convex in front and concave at the rear.

The ventral process (lower branch) of the squamosal, which extends onto the cheek region of the skull, contacts a smaller crescent-shaped bone near the jaw joint. Under Bartholomai's interpretation, this bone was a fragment of the jugal (cheek bone), but Ezcurra reinterpreted it as a strap- like quadratojugal bone, which was near the jaw joint. Regardless of these interpretations, the rear branch of the jugal would not have been long enough to enclose the lower temporal fenestra. The lower temporal fenestra (also known as the infratemporal fenestra) was typically a large hole on the side of the skull, although it was not completely enclosed from below in many lepidosaurs (the group of reptiles containing lizards, snakes, and the tuatara) and a few archosauromorphs (such as Prolacerta and Kadimakara).

Stenoma fenestra is a moth in the family Depressariidae. It was described by August Busck in 1914. It is found in Panama."Stenoma Zeller, 1839" at Markku Savela's Lepidoptera and Some Other Life Forms.

Additionally, a narrow strip of smooth bone on the lacrimal bone in front of the eye sockets forms the margin of the antorbital fenestra and the associated antorbital fossa, which are distinctly archosauriform characteristics.

The depression of erythrosuchids is a remnant of the pineal foramen that was present in more primitive reptiles. The lack of a depression in the skull table of Youngosuchus suggests that it belongs to a more derived group than erythrosuchids. Another difference between Youngosuchus and erythrosuchids can be seen in the antorbital fenestra, a hole in the skull in front of the eyes. In Youngosuchus, the fenestra is large and triangular, but lacks the depressed upper and front margins seen in the skulls of erythrosuchids.

Carnivory can be inferred for Teleocrater from the single tooth that was preserved, which is compressed, recurved, and bears serrations on both edges. Like other members of the Archosauria, the recess in the maxilla in front of the antorbital fenestra (the antorbital fossa) extends onto the backward- projecting process of the bone, and the palatal projection of the two maxillae contacted each other. Additionally, like early dinosaurs, there is a depression on the frontal bone in front of the supratemporal fenestra (the supratemporal fossa).

The nasoantorbital fenestra, the large skull opening, is relatively long at 58% of the skull length. The lower jaws have a length of . The skull is similar to that of Istiodactylus, which lived at about the same time in what is now England, especially in the teeth that are compressed side to side and the long fenestra. However, it differs from Istiodactylus in several details, including a significantly lower skull, different jugal and a slight curve to the upper margin of the lower jaw.

The nostril openings were oval and, as in all spinosaurids, positioned farther back on the skull than in typical theropods. Irritators nostrils were both proportionately and absolutely smaller than in Suchomimus and Baryonyx, but larger than those of Spinosaurus. The opening behind the orbit (eye socket), the lateral temporal fenestra, was very large, while the antorbital fenestra, in front of the eyes, was long and elliptical. The orbit itself was deep and wider at the top (where the eyeball was placed) than the bottom.

It was small, possessing a single large spike and firmly connecting to the quadrate bone of the jaw joint. The discovery of a quadratojugal in weigeltisaurids reveals that the bone which formed the rear edge of the temporal fenestra was the squamosal bone. The squamosal of Rautiania was tall and slightly slanted backwards; it was fringed with large spines oriented outwards, as is typical for weigeltisaurids. The upper edge of the temporal fenestra is formed by the parietal bone, which differs in structure between Rautiania species.

They were oval shaped in cross-section, and uniquely lacked serrations while also having pronounced longitudinal ridges along their labial and lingual (cheek- and tongue-facing) sides. A three-pronged bone has been identified as the postorbital. Its structure is similar to that of most diapsid reptiles, indicating that Jaxtasuchus likely retained a lower temporal fenestra like other diapsids. This contrasts with Doswellia, which has a smaller and stouter postorbital bone and a lower temporal fenestra which has been completely closed up, giving it a euryapsid skull.

Its front edge formed the rear rim of a supratemporal fenestra, a hole in the upper part of the skull behind the orbits. The rear part of the squamosal connected to the quadrate and had a triangular horn-like structure similar to that of Doswellia. The postorbital is missing in the fossil, but its position relative to other bones can be inferred by the space it left behind. It would have been tightly connected to the jugal, squamosal, and frontal, leaving no space for an infratemporal fenestra.

Most archosauriforms possess a hole known as a mandibular fenestra where the dentary, angular, and surangular meet. However, it cannot be determined if Vancleavea also possessed this hole. It is plausible that it was lost through evolution (as is the case with the antorbital and supratemporal fenestrae), but there is also the possibility that it was too small to be noticeable in the preserved Vancleavea skull. A small and sometimes overlooked mandibular fenestra is present in Proterosuchus, one of the first archosauriforms to evolve.

The word itself comes from the Occitan term for a small window, and is ultimately derived from the Latin word fenestra for window.Prouty, Ray. Helicopter Aerodynamics, Helobooks, 1985, 2004. p. 266."30 Years of Innovation." fenestron.com.

The smallest species in this genus: the skull length of the holotype is 6 cm. Differs from B. minor by having a more steeply arched back, smaller facial plates and a lack of a postpineal fenestra.

The choanal septum is also ridged on the ventral surface. An autapomorphic single parachoanal fossa rostrolateral to the parachoanal fenestrae is present at the base of the pterygoid wing. In the lower jaw of Aplestosuchus, the outer sculpture of the mandible is limited to the dentary, and the occipital surface of the mandibular symphysis lack a peg. Additionally, the ridged border of the angular is not covering the rostral edge of the mandibular fenestra, and a row of foramina is present between the mandibular fenestra and the ectopterygoid-jugal suture.

The lacrimal bone had a unique, thickened upper rim, where it formed the upper border at the back of the antorbital fenestra. The prefrontal bone formed the roof of the orbit (eye socket), and had an L-shaped bar that made part of the upper surface of the orbit concave. The orbit was oval, and narrow towards the bottom. The jugal bone had two upwards pointing processes, the first of which formed part of the lower margin of the antorbital fenestra, and part of the lower margin of the orbit.

Teyujagua provides a form of transitional morphology between Archosauriformes and other earlier archosauromorphs. Features previously considered unique to Archosauriformes, including the external mandibular fenestra and serrated teeth, are found in Teyujagua, and demonstrate that the key traits of Archosauriformes were acquired in a mosaic fashion, rather than evolving all at once. Furthermore, these features broadly relate to dietary adaptations, suggesting that archosauriform skulls were first being adapted for a predatory, hypercarnivorous lifestyle prior to the acquisition of features relating to pneumaticity (e.g. the antorbital fenestra and a closed temporal bar) that characterise later Archosauriformes.

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. The two groups of averostrans, Ceratosauria and Tetanurae, both survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of tetanurans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Squamates, the group containing modern lizards and snakes, also lack a quadratojugal, but early squamate relatives such as Marmoretta do retain the bone. Ichthyosaurs, a group without a lower temporal bar, have a quadratojugal that is taller than it is long, stretching above (rather than below) the open infratemporal fenestra to contact the postorbital bone (rather than the jugal). Early turtles such as Proganochelys also have a tall quadratojugal, which contacts the jugal without any trace of the infratemporal fenestra. dromaeosaurid dinosaur Dromaeosaurus, with the quadratojugal (light blue) labelled.

In addition, the antorbital fenestra, an opening in the skull between the eye socket and nostril, was lost during the evolution of Psittacosauridae, but is still found in most other ceratopsians and in fact most other archosaurs. It is considered highly unlikely that the fifth digit or antorbital fenestra would evolve a second time. In 2014, the describers of a new taxon of basal ceratopsian published a phylogenetic analysis encompassing Psittacosaurus. The below cladogram is from their analysis, placing the genus as one of the most primitive ceratopsians.

The infratemporal fenestra (opening) behind the eye was narrow and sloped backwards, and the supratemporal fenestra on the top back of the skull was very reduced in size, due to the thickening of the frontoparietal. The (floor of the ) was shortened and distanced from the regions below the orbits and around the palate. The occiput sloped backwards and down, and the occipital condyle was deflected in the same direction. The lacrimal bone formed the lower front margin of the orbit, and its surface had rows of node-like ornamentation.

The crest extended hindwards and down, forming a round arch at the highest point. The diameter of the orbit (eye opening) was 52 mm (2 in); the eyes looked large due to the shortness of the skull. The antorbital cavity in front of the eye consisted of two fenestrae (openings); a large antorbital fenestra at the back, and a small maxillary fenestra at the front. Nemegtomaia was distinct from other oviraptorids in that the frontal bone on the midline of the skull was about 25% the length of the parietal bone from front to back.

Plagiosuchus has a relatively long skull for a plagiosaurid, approximately as long as it is wide. However, its most defining feature is its greatly enlarged orbit, which forms a massive orbitotemporal fenestra with the loss of several post-orbital bones, including the postfrontal and the postorbital, and the reduction of several others. This fenestra is about 80% of the total length of the skull. The subtemporal vacuity on the palate is also correspondingly long, while the tooth rows are short, confined to the anterior portion of the skull.

Several parietal bones are known in Europasaurus, which show a rectangular shape much wider than long. the parietals are also wide when viewed from the back of the skull, being slightly taller than the foramen magnum (spinal cord opening). The parietals contribute to about half the post-temporal fenestra (opening above the very back of the skull) border, with the other region enclosed by the squamosal bones and some braincase bones. Parietals also form part of the edge of the supratemporal fenestra, which is wider than long in Europasaurus, like in Giraffatitan, Camarasaurus and Spinophorosaurus.

Further back on the skull, the quadrate bone articulates with the squamosal bone above and the lower jaw below; the long shaft at the rear of the quadrate is very strongly angled, forming an angle of 160° with the jaw margin, like other ctenochasmatids. The jaw joint is directly underneath the eye socket. At the back of the maxilla, the palate form a wide shelf which is deeply notched at the back, forming in part the suborbital fenestra. Small spikes along the midline of the suborbital fenestra represent the palatine bones, which contact the maxilla.

The rear edge of the skull is somewhat difficult to interpret even in well-preserved specimens such as GR 138. The upper rear corner of the temporal fenestra is formed by the squamosal bone, which connects to the back of the postorbital bone and the parietal bone, as well as the braincase. The front edge of the squamosal possesses a deep 'pocket', while the lower portion of the bone expands into a large downward-pointing 'hood'. A thin structure known as a ventral process stretches downwards, forming the rear edge of the temporal fenestra.

Another small species: the skull length of the holotype is 7.4 cm long. It differs from B. gracilis by having a posterio-median notch on the nuchal plate, the presence of a postpineal fenestra, and larger facial plates.

There is a postorbital process on the jugal. The zygomatic arch is very slender. The parietal borders the temporal fenestra dorsally and is expanded posteriorly on the midline of the parietal foramen. The parietal crest is usually quite long.

The antorbital fenestra was relatively short. The lacrimal bone had a distinctive lacrimal horn on top; its lower end was broad in side view. The eye socket was tall with a pointed lower end. The jugal was long and transversely thin.

In these reptiles, the lower temporal fenestra attained an arch-like shape. The Kadimakara holotype has also preserved fragments of the braincase and the rear part of the palate. The rear part of the shallow lower jaw was also preserved.

Like L. ferox, the premaxillaries separate the frontals. The temporal fenestra is longer than it is wide. It retains the primitive plesiosaur feature of posterior sloping of the skull. The quadrate is firmly attached, unlike the attachments seen in most polycotylids.

Pp. 308-309. Physically it was very similar to Rhamphorhynchus, albeit with notable cranial differences. For one, Scaphognathus had a proportionately shorter skull (4.5 in) with a blunter tip and a larger antorbital fenestra. Its teeth oriented vertically rather than horizontally.

The Monofenestrata are an unranked group of pterosaurs that includes the family Wukongopteridae and the suborder Pterodactyloidea. The clade Monofenestrata was in 2009/2010 defined as the group consisting of Pterodactylus and all species sharing with Pterodactylus the synapomorphy, shared derived trait, of an external nostril confluent with the antorbital fenestra, the major skull opening on the side of the snout. The name is derived from Greek monos, "single", and Latin fenestra, "window". The concept was inspired by the discovery of Darwinopterus, a species combining a pterodactyloid-type skull with a more basal build of the remainder of the body.

The maxilla is fairly typical in shape, with a short anterior process (front branch), a slanted dorsal process (upper branch), a long posterior process (rear branch), and an antorbital fenestra defined between the dorsal and posterior processes. The anterior process has a notch at its front tip followed by a pit, as with a few other archosauromorphs. The dorsal and posterior processes both taper rearwards like other early archosauriforms, and there may be a subtle antorbital fossa (depressed area) in front of the antorbital fenestra. The inner surface of the maxilla has an arched ledge overlooking broad interdental plates.

The portion of the jugal which rises behind the eye socket has a very wide base, and its surface is set inwards relative to the portion below the eye socket. As with other diapsids, Turfanosuchus had a pair of openings at the rear portion of the skull known as temporal fenestra. The bone separating the two holes, the squamosal, had a lower branch which curved forwards to contact the jugal and divide the lower temporal fenestra into two separate holes, leaving three holes at the back of the skull in total. This trait is also known is rauisuchids such as Postosuchus.

The hindmost part of the surangular had a small foramen placed in the same position as similar openings in the mandibles of non-bird theropods and modern birds. The splenial bone was three-pronged (as in some modern birds, but unlike the simple splenial of Archaeopteryx), and its lower margin followed the lower margin of the mandible. There was a large rostral mandibular fenestra and a small, rounded caudal fenestra behind it. Though only five specimens preserve parts of the beak's keratinous covering, these show that there would have been differences between species not seen in the skeleton.

As in Howesia but not Mesosuchus and most rhynchosaurids (where it contacts the quadratojugal), the back portion of its jugal is short and ends at approximately 50% of the front-to-back length of the infratemporal fenestra. Unlike in both Howesia and Mesosuchus, but similarly to the rhynchosaurids, the elongated back portion of the postorbital ends above the front margin of the bottom portion of the squamosal. Finally, as in Mesosuchus and Rhynchosauridae (but not Howesia), the elongated bottom portion of the squamosal extends for more than 50% of the back margin of the infratemporal fenestra.

They were isodont, or all equal in size and shape, in adult individuals, but in juveniles, the teeth were less strongly curved in the back of the jaw. The skull of Proterosuchus exhibits many features characteristic of its position as a basal archosauriform. It bears a prominent antorbital fenestra, like most archosauriforms. In some specimens, the jugal and quadratojugal contact to complete the ventral margin of the lower temporal fenestra, as in other archosauriforms, but in other specimens, there is a narrow gap between the bones so that the lower temporal bar is incomplete as in non-archosauriform archosauromorphs.

It has also been suggested that heterodontosaurs and other basal (or "primitive") orhithischians had lip-like structures like lizards do (based on similarities in their jaws), rather than bridging skin between the upper and lower jaws (such as cheeks). The proportionally large lower temporal fenestra was egg-shaped and tilted back, and located behind the eye opening. The elliptical upper temporal fenestra was visible only looking at the top of the skull. The left and right upper temporal fenestrae were separated by the sagittal crest, which would have provided lateral attachment surfaces for the jaw musculature in the living animal.

This is similar to the case in other ornithosuchids, and Venaticosuchus particularly resembles Riojasuchus due to the maxilla curving upwards behind the diastema and the premaxilla hooking downwards in front of it. The premaxilla is not preserved well enough to conclude anything about its tooth count, but other ornithosuchids had three premaxillary teeth. The maxilla in general resembles that of Riojasuchus, with a triangular antorbital fenestra with a tapering front tip. On the other hand, the antorbital fossa (the basin in which the antorbital fenestra lies) is shallower, smaller, and more smoothly textured than that of Riojasuchus.

The nasals are so reduced in size (especially compared to Philydrosaurus) that they are completely surrounded by the prefrontals and premaxillary bones, and fail to contact the toothed maxillary bones. The postorbital and postfrontal bones (which lie behind the eye) are separate from each other; in many other choristoderes these bones fuse into a single postorbitofrontal bone. The rear of the skull is not particularly unusual, with each side of the skull having two holes known as temporal fenestrae (as with other diapsids). The upper temporal fenestra is not elongated (unlike neochoristoderes), but the lower temporal fenestra is low and long.

Behind the jugal is the quadratojugal, which has traditionally been depicted as hypertrophied and occupying the location of the back portion of the jugal; it is actually a small, half moon-shaped bone wedged between the jugal and the quadrate and situated below the elongate infratemporal fenestra. Overall, the infratemporal fenestra is shaped similarly to the eye socket. The quadrates are strap-like, and wrap around from the back to the bottom of the skull. Although mostly obscured, the removal of the parietal during preparation has exposed part of the endocast of the brain, which has a large flocculus and cerebrum.

A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is Latin for the word "window", and is used in various fields to describe a pore in an anatomical structure.

In plant biology, the perforations in a perforate leaf are also described as fenestrae, and the leaf is called a fenestrate leaf. The leaf window is also known as a fenestra, and is a translucent structure that transmits light, as in Fenestraria.

Carleton and Musser, 1989, p. 30 The condition of the arteries in the head is highly derived.Weksler, 2006, p. 37 The subsquamosal fenestra, an opening in the back part of the skull determined by the shape of the squamosal bone, is present.

This is in contrast to typical tanystropheids, which have the pubis and ischium curve towards each other, often contacting each other at the bottom to enclose a hole termed the thyroid fenestra. A portion of the square-shaped femoral head is also preserved.

2012, technical diagnoses for dromaeosaurines can be established based on the following traits: fully serrated teeth; vertically oriented pubis; pubic boot (or end) projecting anteriorly and posteriorly; the jugal process of the maxilla, in a ventral view to the external antorbital fenestra, is dorsoventrally wide.

Hyalurga fenestra is a moth of the family Erebidae. It was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. It is found in Costa Rica, Nicaragua, Panama, Bolivia, Suriname, French Guiana, Brazil, Peru and Venezuela, as well as on the Antilles.

Even a mandible from the Lower Anisian Mukheiris Formation in Jordan was discovered, and shared many similarities with the genus, including a similarly sized Meckelian fenestra on the inner surface of the lower jaw, teeth with sharp edges, and large fangs in the upper jaw.

Halticosaurus orbitoangulatus. In 2000, Rauhut and Hungerbuhler reassigned this material to the genus Saltoposuchus, a crocodylomorph, based on the morphology of the teeth and the antorbital fenestra in the skull.Rauhut, O.M.W. & Hungerbühler, A. (2000) "A review of European Triassic theropods." Gaia, 15: 75-88.

The maxillary tooth row is positioned at some distance from the jaw rim. A fenestra promaxillaris is present. The branch of the jugal towards the postorbital is long, slender and inclined to the rear. The foramen magnum is much larger than the occipital condyle.

The parietal foramen (a hole which holds the "third eye" in modern tuataras) is teardrop-shaped. The postorbital, jugal, and squamosal bones on the side of the head curve upwards to form the bar between the upper and lower temporal fenestrae. The jugal lacks a "subtemporal extension" forming the bottom edge of the lower temporal fenestra, leaving the hole open from the bottom as if it was an arch. The squamosal also forms a large portion of the part of the skull behind the lower temporal fenestra, along with a thin and tall quadratojugal and a curved quadrate which probably supported a tympanic membrane (eardrum).

Behind the maxilla, the indentation known as the antorbital fossa bears two large openings (the antorbital fenestra and the elongated, enlarged maxillary fenestra) that stretch from the top margin to the bottom margin of the fossa; Sinovenator, Sinornithoides, and Sinusonasus have one additional opening known as the promaxillary opening. The bar of bone separating the fenestrae is narrow, like in Sinovenator. The lacrimal bone, encircling the fossa from above and behind, has a long forward-projecting branch much like other troodontids. However, the descending branch of the bone is also nearly the same length, and the descending branch also bears a unique ridge on its front portion.

The back of the skull is deep and broad, with a large temporal fenestra that is roughly trapezoid in shape and slopes down and back from the roof of the skull. There is a small, thin parietal crest of bone in the middle of the skull between the eyes and temporal fenestra. What is known of the premaxilla suggests that it had a broad, flattened plate that opposed the beak-like lower jaw and likewise was also toothless. A jaw fragment containing two large "canines" are also known from this specimen, although it is unknown if it is from the lower or upper jaw.

Like other dicynodonts, Taoheodon had a short skull with large temporal fenestra at the back, large orbits and a short snout, which in Taoheodon was proportionately short even for a dicynodont. Its skull is slightly longer than wide, with elongated temporal fenestra. The external nostril is rounded and not especially large for a dicynodont, but the area of bone behind and beneath it is hollowed out and concave compared to the rest of the snout. The nasal bones along the roof of the snout are relatively flat, but are nonetheless rugosely textured and bore a single weakly developed boss of tough skin or keratin on top of the snout.

The parietal is one of the main bones used to distinguish centrosaurine taxa from each other and resolve relationships between them, whereas the squamosal is very similar across taxa. In Achelousaurus, the squamosal bone was much shorter than the parietal. Of its inner margin the rear portion formed a step in relation to the front part, with the suture between the squamosal and the parietal showing a kink to behind at the level of the rear supratemporal fenestra, a typical centrosaurine trait. The squamosal and the jugal bone, by touching each other, excluded the quadratojugal from the edge of the lateral temporal fenestra, i.e.

Nanchangosaurus holotype Hupehsuchia was first defined as a suborder of "Thecodontia" in 1972, when it was first thought to be a group of early archosaurs. It was also thought to be related to several other groups of Triassic reptiles previously thought to be clearly distinct. The presence of the supposed antorbital fenestra described above was seen as evidence for grouping hupesuchians within Archosauria, but the antorbital fenestra characteristic of archosaurs is surrounded by the maxilla and lacrimal, not the nasal and prefrontal bones. The dermal plates were also seen as evidence for terrestrial archosaur ancestors, and comparisons were made with some early armored forms.

Additionally, W. scurriensis differs from both species of Paleorhinus in the presence of a ridge, rather than a row of nodes, on the lateral surface of the jugal. The small partial skull previously catalogued as referable to this species, TTU P-11422, does not share any diagnostic characters with the holotype. The specimens can be compared only in the area surrounding the right antorbital fenestra. Although TTU P-11422 does have a large antorbital fossa with a slightly posterodorsally inclined antorbital fenestra as in W. scurriensis, but the nasals just posterior to the nares are not swollen in contrast to the autapomorphic condition seen in the latter.

Between dentary, surangular and angular a rather tall triangular mandibular fenestra is present. The dentary bears twenty-one teeth, which are slightly larger than those of the upper jaws. All teeth of Jiangjunosaurus are symmetrical with a triangular profile. Front and rear edges have both seven denticles.

The external naris was large and retracted. Eurhinosaurus had elongated, slender and straight teeth without distinct surface ornamentation of the crown. Their teeth were delicate, sharply pointed and the enamel was smooth. Their fenestra supratemporalis was small and external exposure of the frontal was strongly reduced.

Witmer, L.M. 1997. The Evolution of the Antorbital Cavity of Archosaurs: A Study in Soft-Tissue Reconstruction in the Fossil Record with an Analysis of the Function of Pneumaticity. JVP 17(1 supp):1–76. Although crocodylians walled over their antorbital fenestra, they still retain an antorbital sinus.

Cracraft, Joel (1974) Paleognathes share similar pelvis anatomy. There is a large, open ilio–ischiatic fenestra in the pelvis. The pubis and ischium are likely to be longer than the ilium, protruding out beneath the tail. The postacetabular portion of the pelvis is longer than the preacetabular portion.

One of the largest species in this genus: the skull length of the holotype is around 20 cm. Has a postpineal fenestra, an unusually long (for the genus/family) lateral trunk shield, and comparatively small orbits. The dermal bones are decorated with a pattern of small, evenly spaced tubercles.

The antorbital fenestra is large instead of very small. The maxilla is short and deep, half as tall as long, instead of having a height a third of the length. The basisphenoid of the lower braincase is short instead of long. Thirteen neck vertebrae are present instead of ten.

The teeth are supported from behind by tall, triangular, unfused interdental plates. The cutting edges bear eighteen to twenty denticula per centimetre. The tooth formula is probably 4, 13–14/13–14. The jugal bone is pneumatised, pierced by a large foramen from the direction of the antorbital fenestra.

The eye socket behind it is rather high. It is constricted in the middle by bony projections of the lacrimal bone in the front and the postorbital bone at the rear. The eye was located above the constriction. Behind the eye socket a large triangular infratemporal fenestra is present.

Apart from the size, the describers established some diagnostic traits. The jaws are very elongated and have straight edges. The total number of teeth in the skull is at least sixty-two. The large skull opening, the fenestra nasoantorbitalis, is rectangular and represents 22% of the snout length.

Agnidra fenestra is a moth in the family Drepanidae. It was described by John Henry Leech in 1898. It is found in north-eastern Myanmar and the Chinese provinces of Sichuan, Yunnan and Shaanxi. The wingspan is 12–14 mm for males and 13–15.5 mm for females.

Restoration of Wukongopterus lii Wukongopterids are characterized by a unique combination of "primitive" and advanced pterosaurian features. While they had long tails and other features characteristic of other "rhamphorhynchoids", they also had distinct pterodactyloid features, such as long vertebrae in the neck and a single skull opening in front of the eyes, the nasoantorbital fenestra (in most "rhamphorhynchoids", the antorbital fenestra and the nasal opening are separate). This feature lead to Darwinopterus modularis being placed by Lü e.a. in a new clade of pterosaurs, the Monofenestrata, or "with a single opening", forming this group together with the true Pterodactyloidea, to the exclusion of the Rhamphorhynchidae and other more primitive pterosaurs which had separate nasal and antorbital fenestrae.

Although the postcranial skeleton of Thalassodromeus is unknown, relatives had unusually short and blocky neck vertebrae, with well-developed front and hind-limbs that were almost equal in length (excluding the long wing-finger). The hindlimbs were 80 percent that of the forelimb length, a unique ratio among pterodactyloids (short-tailed pterosaurs). As a pterosaur, Thalassodromeus was covered with hair-like pycnofibres and had extensive wing membranes (which were extended by the wing finger). The skull of T. sethi had a streamlined profile, especially from the tip of the snout to the front edge of the nasoantorbital fenestra (opening which combined the antorbital fenestra in front of the eye with the bony nostril).

Across eusthenopterids (tristichopterids), a trend exists showing increasingly higher values for this ratio in more derived genera with Eusthenodon possessing the highest value with a frontoethmoidal shield to parietal shield ratio of 2.30. The further expansion of snout length in many tetrapod species may also be further evidence supporting the tendency of increasingly longer frontoethmoidal shields present in subsequent clades closely related to eusthenopterids including the late eopods. The orbital fenestrae housing the small eyes of Eusthenodon were distinctly smaller in size compared to the size of the larger frontoethmoidal shield. Residing posteriorly to the orbital fenestra, the posterior supraorbital bone extends downwards along the fenestra and comes into contact with lachrymal.

This part joins with the two finger-like processes of the maxilla, which is similar to Protohadros. The body of the maxilla itself does not bear a recess or any indication of an antorbital fenestra, like Equijubus, Protohadros, and other hadrosauroids. One of the characteristics used to distinguish Eolambia is the concave profile of the tooth row of the maxilla when viewed from the side, which is like Equijubus, Probactrosaurus, and several other hadrosauriforms but unlike Protohadros. Like Probactrosaurus and other hadrosauroids, the back of the maxilla connects to the jugal – which borders the bottom of the eye socket and infratemporal fenestra – through a finger-like projection that fits into a recess.

The maxilla extends backwards in a half-moon shape to encircle the front end of the fenestra, with the top prong of the maxilla forming a 45° angle with the horizontal. The top end of the fenestra is enclosed by the thin, rectangular, and slightly concave nasal, and the lacrimal, which is not well-preserved but may have been long, slender, and triangular. On the underside of the skull, the maxilla forms the majority of the palate (not the premaxilla, as previously assumed), extending back from below the external nostrils. Along the midline of the maxilla is situated a thin strip of bone, the vomer, which connects back to join the pterygoid.

The external mandibular fenestra is large. The dentary, lower jaw, teeth are quite pointed and have no front edge denticles; their rear edge is very straight. The holotype preserves a furcula and a basket of fifteen pairs of gastralia. The arms are weakly developed, with a slender humerus and ulna.

Zoological Journal of the Linnean Society, 114(3), 307-348. The opening of the otic wall of the braincase can be considered a paedomorphic feature for tetrapods and is linked to the stapes functionally.Clack, J. A. (1994). Earliest known tetrapod braincase and the evolution of the stapes and fenestra ovalis.

The holotype IVPP V12560 is an articulated skeleton measuring approximately in length. The specimen is unique among all known ankylosaur fossils in the retention of the external mandibular fenestra. Antorbital fenestrae may also be present. It has relatively large teeth, including teeth in the praemaxilla ( primitive or possibly juvenile trait).

Behind the dentary was a moderately large mandibular fenestra. Individuals of Desmatosuchus were heavily armored. The carapace was made up of two rows of median scutes surrounded by two more rows of lateral scutes. The lateral scutes had well-developed spine-like processes which pointed out laterally and dorso-posteriorly.

Skull diagram Specimens reveal that Petrolacosaurus had a slightly elongated skull with two temporal fenestrae. The upper temporal fenestra is located posteriorly to an enlarged orbit. This is a distinctly diapsid character. The largest teeth in the jaw were at the front of the snout, erupting from the premaxilla bone.

The structure of the upper jaw, with a low ridge above, and running parallel to, the tooth row, indicates the presence of a fleshy cheek. In stegosaurians, the typical archosaurian skull opening, the antorbital fenestra in front of the eye socket, is small, sometimes reduced to a narrow horizontal slit.

The holotype, IWCSM. 2020. 401, was found in a layer of the Wessex Formation dating from the Barremien. It consists of partial paired praemaxillae, lacking the snout tip and broken off at the rear before the front edge of the fenestra nasoantorbitalis. The fossil is lightly eroded, transversely compressed and deformed.

A unique characteristic or autapomorphy of Asperoris is the rough texture of its skull bones, particularly the frontal. The skull roof of Asperoris is relatively thick compared to those of other archosauriforms and its antorbital fenestra, a hole in the side of the skull in front of the eye socket, is relatively narrow.

Megalancosaurus preonensis was first described in 1980. Its discoverers interpreted it as an archosaur, based in part on the belief that it had an antorbital fenestra. In 1994, two specimens originally thought to be juveniles of Drepanosaurus were assigned to the species. This discovery led to the realization that it was a drepanosaurid.

Like most post-Triassic ichthyosaurs, the parietal foramen was located on the connection point between parietal and frontal. The temporal fenestra was extremely small. Skull The supratemporal of Eurhinosaurus was very large and wide in the dorsal view, reaching the orbital margin. Its frontal was covered by nasals in the dorsal view.

One of the most apparent of these features being that its skull is wider than it is tall, resulting in a triangular shape, when viewed dorsally. In connection with this, the temporal fenestra angle out posterolaterally. Compared to other dicynodonts, the external naris is retracted and located relatively high on the snout.

The maxilla was long and low, with 15 tooth sockets. It was covered with irregular pits and had an incision at its rear edge, likely representing the antorbital fenestra. Fragments of premaxilla and nasal bones were also preserved, with a similar texturing to the maxilla. The teeth were sharp and slightly curved.

It differs in size, the known skulls averaging a length of and in form to D. terrelli. In D. marsaisi, the snout is narrower, and a postpineal fenestra may be present. Many researchers and authorities consider it a synonym of D. terrelli. H. Schultze regards D. marsaisi as a member of Eastmanosteus.

As well as the derived, sauropodomorph-like features, the skull also had numerous primitive traits for archosauromorphs, including an open-bottomed lower temporal fenestra, extensive palatal teeth, a pineal foramen and no external mandibular or antorbital fenestrae. However, its exact relationships still remained unknown beyond a position as an indeterminate non-archosauriform archosauromorph.

The outer side of the squamosal has a well-developed drooping flange covering, in side view, the upper rear part of the lateral temporal fenestra. The tenth neck vertebra has a clear depression on its front underside. The neck and dorsal vertebrae are not keeled. In 2012 Matthew Carrano added to these traits.

The palatal fenestra of the lower caniniform merges with the internal naris. A portion of the vomer separates the choanae, and bears specialized transverse processes just anterior to the contact with the premaxilla. The vomers are either fused anteriorly or completely fused. No palatine teeth have ever been found on specimens of Theriognathus.

Between the tooth row of the premaxilla and that of the maxilla there was no hiatus. The maxillary teeth were few in number, eight with the holotype. The depression or fossa for the large skull opening, the fenestra antorbitalis, was long and extended far to the front. The humerus was relatively short.

Above the eye sockets however, the line of the top of the snout curves steeply upwards, resulting in a very large crest on the frontals, as high as the posterior part of the skull is deep, ending in a rounded top. Due to the angling of the skull roof the crest slightly points forwards and its base extends to the back of the roof; however, the parietal is not part of it. In front of the crest large impressions of soft tissue are visible but these are plant remains. Further diagnostic features of the skull include an infratemporal fenestra with a narrow lower end, and a jugal of which the front branch extends no further than the front edge of the fenestra nasoantorbitalis.

Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism. According to Xu (2010), Sinoceratops can be distinguished based on the following diagnostic characteristics: there are at least ten robust, strongly curved hornlike processes along the rear margin of the combined parietals, while at the same time at least four hornlike processes on the combined squamosals are present; there is a large accessory fenestra in front of the antorbital fenestra (differing from all other known centrosaurines); the external margin of the parietals is only weakly undulating (differing from all other known centrosaurines); and the presence of broad-based epoccipitals (differing from all other known centrosaurines).

Restoration of a crested D. modularis Darwinopterus, like its closest relatives, is characterized by its unique combination of basal and derived pterosaurian features. While it had a long tail and other features characteristic of the 'rhamphorhynchoids', it also had distinct pterodactyloid features, such as long vertebrae in the neck and a single skull opening in front of the eyes, the nasoantorbital fenestra (in most 'rhamphorhynchoids', the antorbital fenestra and the nasal opening are separate). Darwinopterus is distinguished from its close relatives by the greater relative length of the back portion of the skull compared to its jaws, thin nasal bone, and elongated hip bone (illium). The teeth in all species were spaced widely with the longest teeth at the jaw tips.

Characteristics of E. Delfi skulls include an elongated and platyrostral skull, posterolateral depressions on the alveolar maxillary process, minimal lateral undulation of the tooth row (maxillary), broadened nasals located anteriorly to the prefrontals, a lack of contact between the nasals and external nares, a flattened and broad innerfenestral bar with rims that are raised along the supratemporal fenestra, and a nasopharyngeal septum formed by the anterior divergence of the vomeral processes. The lacrimal bone is rectangular and in dorsal view has an anteroposterior length that is two times its width. The lacrimal is contacted by the prefrontal laterally along its length, which separates the prefrontal from the nasal. A large postorbital bar with a triangular cross-section creates a separation between the orbit and the infratemporal fenestra.

The surangular (a bone which forms the upper edge of the rear part of the mandible) had two spikes on its outer surface and a large area for muscle attachment on its inner surface. Rautiania bones have helped to clarify certain aspects of weigeltisaurid skull anatomy, particularly relating to bones at the rear part of the cranium. As with other weigeltisaurids, the rear part of the skull of Rautiania had a large hole (known as a temporal fenestra) on each side, edged by bones ornamented with spines, thus forming a sort of "crest". The rear lower corner of the temporal fenestra is now known to have been formed by the quadratojugal bone, since a three-dimensionally preserved quadratojugal has been discovered in Rautiania.

Regarding its skull structure, the features that distinguish Biseridens from other anomodonts include having an intertemporal region that is wider than the interorbital region, and a temporal fenestra larger than the orbits. Additionally, the mandibular fenestra is absent from the lower jaw, the transverse flange of the pterygoid extends laterally, and there is contact between the tabular and opisthotic, or the posterior part of the otic capsule. There is a concavity on the posterior region of the postorbital bone as well as a lateral process on the postorbital that fails to reach the zygomatic arch. Characteristic of other basal therapsids, the prominent maxilla constitutes the majority of the snout and the nasal bones are the longest bones of the skull roof.

Life restoration Possible size estimated by Holtz 2012 The maxilla is long and low, with the process above the antorbital fenestra being horizontal, similar to other advanced troodontids. However, some features of the maxilla are more similar to the condition in basal troodontids such as Sinovenator. These include the presence of a promaxillary fenestra which is visible in lateral view, a narrow promaxillary strut (the bar of bone between the maxillary and promaxillary fenestrae), and a narrow interfenestral strut (the bar of bone between the maxillary and antorbital fenestrae). Geminiraptor is uniquely characterized by the presence of a large pneumatic chamber which expands the maxilla into a triangular shape in cross section, with the base formed by a bony shelf lingual to the teeth.

Many early saurischians have a hole called the promaxillary fenestra situated on the antorbital fossa, but this hole is absent in Gnathovorax. On the other hand, Gnathovorax does possess a characteristic thin ridge edging an additional emargination within the antorbital fossa; a small depression is present between this ridge and the ridge forming the border of the antorbital fossa. The lower branch of the lacrimal is slender and extends to the middle of the lower edge of the orbit (eye socket), similar to Daemonosaurus but different from Herrerasaurus. Most other aspects of the skull, such as the thick squamosal, expanded front branch of the jugal, the shape of the infratemporal fenestra, and a lack of palatal teeth, are most similar to herrerasaurids among early dinosaurs.

It is elongated and triangular in side view. The snout is appending with a slight kink above the middle of the fossa antorbitalis, which at this point is reinforced by a distinctive vertical bone strut, a pila interfenestralis dividing the depression in two halves: at its rear an oval skull opening, the fenestra antorbitalis, pierces the surface and at its front the uniquely large and deep hollowing out of the maxilla side is visible, in which another opening, the fenestra maxillaris, might have been present, though this is uncertain because of damage. The front of the snout consists of a small praemaxilla, continuing the line of the nasals downwards and forming a small upper beak in front of the lower jaws.

The praemaxilla is short. There is a fenestra promaxillaris, a small opening in the front of the maxilla side, which is rare among troodontids. There are four premaxillary and about twenty- three maxillary teeth. The maxillary teeth have no serrations on their front edge; the denticles on the concavely curved rear edge are small.

An anapsid is an amniote whose skull lacks one or more skull openings (fenestra) near the temples.Pough, F. H. et al. (2002) Vertebrate Life, 6th Ed. Prentice Hall Inc., Upper Saddle River, NJ. Traditionally, the Anapsida are the most primitive subclass of reptiles, the ancestral stock from which Synapsida and Diapsida evolved, making anapsids paraphyletic.

Although Parrish used many traits of the ankle to characterize prestosuchids, Nesbitt showed that these traits were present in various basal suchian groups. In 2004, Benton proposed another trait to define Prestosuchidae: a narrow, triangular antorbital fenestra. However, Nesbitt found this trait in Postosuchus (a rauisuchid), Dromicosuchus (a crocodylomorph), and Fasolasuchus (a basal loricatan).

210x210px A skull diagram of Dromaeosaurus, a dromaeosaurid dinosaur. The postorbital is colored dark blue. The postorbital is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra.

This re-identification has been accepted and followed since then; however, features of its skull such as the differentiated teeth and large temporal fenestra have been described as therapsid-like. No further studies on Dimacrodon have been carried out since then, and it remains unclear what its true phylogenetic relationships are amongst early-derived therapsids.

The prefrontals are large triangular plates which overhang the orbits, with rugose lateral surfaces. All the surfaces which articulate with the other bones of the skull roof are narrow and oblique. The squamosal has five projections. Two of these bordered the superior temporal fenestra and met with the parietal and postorbital, which are not known.

They are easily separated from other amniotes by having a temporal fenestra, an opening low in the skull roof behind each eye, leaving a bony arch beneath each; this accounts for their name.Romer, A.S. & Parsons, T.S. (1985): The Vertebrate Body. (6th ed.) Saunders, Philadelphia. Primitive synapsids are usually called pelycosaurs or pelycosaur-grade synapsids.

The basioccipital has large oblique facets on the lower sides. The opisthotic has an expanded pedicel with facets on its underside. Elongated epistyloid bones project obliquely to the rear and below, from the back of the skull. A small spur-like structure on the upper edge of the paroccipital process encases the posttemporal fenestra.

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The lower jaw has a ventrally protruding flange formed by prearticular and meckelian bone. Also characteristic of Styloichthys is the lyre-shaped trajectory of the supraorbital canal, a fenestra ventralis, small internasal cavities, three coronoids in the lower jaw, an eyestalk and a slender postorbital pila which connects the basipterygoid process and the side of the braincase wall.

Wanosuchus ("Wangjiang County crocodile") is an extinct genus of sebecosuchian mesoeucrocodylian known from ?Paleocene-age rocks of southern Anhui, China. It is based on IVPP V 6262, a nearly complete lower jaw, which is also the only known specimen. The bone lacks an external mandibular fenestra and has thirteen teeth, the longest of which are the fourth and eleventh.

The species name refers to numerous pale spots of ground colour on the forewings and is derived from Greek poly (meaning numerous) and Latin fenestra (meaning window)., 2009: Tortricidae (Lepidoptera) from the mountains of Ecuador and remarks on their geographical distribution. Part IV. Eastern Cordillera. Acta Zoologica Cracoviensia 51B (1-2): 119-187. doi:10.3409/azc.52b_1-2.119-187.

Iguanodontid dentaries are very long as well, and become increasingly thick towards the back of the skull. A pair of bony processes extending from the maxilla insert into the jugal and lacrimal, respectively. The iguanodontid jugal has particularly deep crevices that serve to mediate this contact. The lacrimal process constitutes the rostral margin of the reduced antorbital fenestra.

Longchengpterus is based on holotype LPM 00023, found at Yuanjiawa near Dapingfanga, a compressed incomplete skeleton and partial skull on a single plate. The posterior part of the skull has been damaged. It is elongated with a length of . The large skull opening, the fenestra nasantorbitalis, is triangular in form and occupies much of the snout.

The preserved length of the snout fragment of Unwindia is . Martill estimated that the distance between the large opening in the skull side, the fenestra nasoantorbitalis, and the snout point had been . In 2013, Mark Witton estimated the total skull length at a minimum of , which would indicate a wingspan of over . Martill indicated two distinguishing traits.

Protoceratopsids have a frill and rostral bone characteristic of all ceratopsians. Their snout is particularly wedge-shaped with tall and narrow nostrils situated high on it. The antorbital fenestra is unusually small, and the antorbital fossa sits high on the skull with a slit connecting it to a sinus in the maxilla. This sinus is unique to Protoceratopsidae.

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The maxilla is pierced by a large maxillary fenestra, the diameter of which equals a sixth of the length of the tooth row. The tooth crown equals a quarter of the tooth length, thus including the root. The toe claws have a groove on top. Both praemaxillae are connected by an extra pen-in-socket connection.

The snout is broad, and the skull widens toward the occiput or posterior margin. Two large holes behind the eye socket called temporal fenestrae occupy most of the posterior skull. Between these fenestra is a narrow sagittal crest. In front of this crest, the skull roof bones are weakly pitted with small bumps and ridges for blood vessels.

Thliptosaurus skull with diagram isolating the mandible. The mandibular symphysis of the dentaries is long, creating a long, flattened shovel-like beak tip. The rest of the jaws is otherwise roughly v-shaped, as is typical for dicynodonts. The dentary has a tall plate on its sides that obscures the external mandibular fenestra, an unusual condition amongst dicynodonts.

Teyujagua may have been a semi-aquatic ambush predator along the margins of lakes and streams, as suggested by the dorsally positioned nares, similar to some later Crocodyliformes. The serrated teeth and external mandibular fenestra imply the development of a hypercarnivorous lifestyle as in later Archosauriformes, although the limited binocular vision suggests it was a visually oriented terrestrial predator.

The synapomorphic cetacean air sinus system is partially present in basilosaurids, including the pterygoid, peribullary, maxillary, and frontal sinuses. The periotic bone, which surrounds the inner ear, is partially isolated. The mandibular canal is large and laterally flanked by a thin bony wall, the pan bone or acoustic fenestra. These features enabled basilosaurs to hear directionally in water.

A palpebral with a length equal to half the diameter of the eye socket overshadowed its top section. A sclerotic ring of fifteen small bone plates supported the outer eye surface. The back of the skull was rather high, with a very large and high jugal and quadratojugal closing off a highly positioned small infratemporal fenestra.

The entire piece has a preserved length of . As with most pterosaurs, the snout was hollow, with a supporting internal boxwork of bone, as could be observed at breaks. The jugal bone apparently extended to a point below the front of the large skull opening, the nasoantorbital fenestra. There are at least eight teeth in each maxilla.

On the other hand, the closure (fusion) of the neurocentral sutures in the vertebrae suggest a mature individual. According to Sues et al. (2011), Daemonosaurus can be distinguished based on the following features: the skull is proportionately deep and narrow, with a short antorbital region. The antorbital fenestra is nearly the same size as the external naris (possible autapomorphy).

The alisphenoid strut, an extension of the alisphenoid bone of the skull which separates two openings in the skull, is sometimes present. The subsquamosal fenestra, an opening in the posterior part of the skull, is relatively small. The mastoid bone is completely ossified, lacking the openings that are present in most species of the genus.Weksler et al.

In the original description some distinguishing traits or autapomorphies were established. The front edge of the antorbital fenestra, the large skull opening in front of the eye socket, is straight and vertically oriented. The frontal bone shows a vertical ridge touching the lacrimal bone. The surangular in the lower jaw has a T-shaped cross-section.

Jinzhousaurus has a length of about 7 metres (23 ft) and its skull is about half a metre long. Its snout was elongated with large nares and lacking an antorbital fenestra. The back of the skull was uncommonly wide with a small crest on top. The dentary of the lower jaw has at least seventeen tooth positions.

Behind the postorbital and closing off the supratemporal fenestra is the three-pronged squamosal, which is partially overlapped by the robust, spatula-like paroccipital processes of the occipital. Between the processes is the foramen magnum, which is a oval. Further below is the basoccipital, which forms a rounded plate that encloses the back of the skull.

The skull is approximately 5 – 7 mm in length with reduced kynesis and a more rigid skull for burrowing. The combination of fossorial habits and small size, contributes to the development of a skull configuration that is frequently found in other groups of burrowers and miniaturized species. Among those characteristics are the closure of the supratemporal fenestra and the post-temporal fenestra, the relative large braincase, tubular or scroll-like palatines and modified jaw suspension mechanism with the quadrate articulating with the lateral wall of the braincase. Other characteristics of the skull of blind skinks include the absence of a parietal foramen, a well developed secondary palate formed by three different bones, the maxillae, vomers and palatines which are expanded ventromedially to form a scroll, and the lack of palatal teeth.

It was collected between 1970 and 1972 by Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) personnel; the exact location and rock unit that produced the bone are uncertain. Wanosuchus was named in 1981 by Zhang Fakui of the IVPP. The type species is W. atresus, a reference to the absent fenestra. Zhang classified Wanosuchus under its own family within Sebecosuchia, Wanosuchidae.

The 2011 study established eight unique derived traits or autapomorphies in which Scipionyx differed from its closest relatives. The praemaxilla has five teeth. Where the parietal and the frontal bone make contact, the depression in which the supratemporal fenestra, a skull roof opening, was present, shows a sinuous ridge on the postorbital. The lower branch of the squamosal has a rectangular end.

The conglomerate is interpreted as debris flows along a lake margin. Redondavenator was named in 2005 by Sterling Nesbitt and colleagues. The type species is R. quayensis, referring to Quay County. The preserved portion of the skull includes the premaxillae (snout tip) and parts of the maxillae (main tooth-bearing bones of the upper jaw) and nasals, in front of the antorbital fenestra.

On the other hand, the rear branch jugal bone lengthens to fill some of the space left by the shortening of the anterior process of the quadratojugal. In archosauriforms, the jugal even re-encloses the lower temporal fenestra. The stapes are long, thin, and solid, without a perforating hole (stapedial foramen) present in the more robust stapes of other reptiles.

The point of the snout curves downwards combined with a slightly concave lower edge of the upper jaw. The paired points of the snout are not separated. The ascending branch of the jugal bone, connecting to the lacrimal bone, is strongly reclining at an angle of 115 degrees. In the rear of the palate a reduced split-shaped fenestra postpalatina is present.

The dentary of the lower jaw likewise bears an estimated twenty to twenty-five teeth. The nostrils are relatively retracted. They are also unique for a theropod in being obliquely oriented to the top in front view. Despite the length of the snout, the main opening in the side of the front skull, the antorbital fenestra, is short; shorter than high.

It differs from other species in the proportions of its nasoantorbital fenestra, its rostral index, the relative sizes of its femur and tibia, and the relative sizes of the first and second wing digits. The cladogram below follows the 2014 analysis by Andres and colleagues, showing the placement of two Sinopterus species ("S." gui and S. dongi) within the clade Tapejaromorpha.

The combined upper side of the nasal bones is pierced by two paired oval openings. The antorbital fossa, with ankylosaurs the remnant of the antorbital fenestra, extends over the contact point of the maxilla, lacrimal bone and jugal bone. The prefrontal bone extends to below, touching the maxilla. At least some dorsal vertebrae have an elongated centrum, 30% longer than wide.

The exit for the facial nerve is present on the vestibule, and the lamina separating the metotic foramen and the fenestra ovalis is very thin. The back vertebrae are only slightly elongated and are not constricted from the sides. The diapophyses are thick, subrectangular, and elongated. The prezygapophyses are short while the neural spines are long and oval-shaped in cross section.

Instead, Sereno listed a single synapomorphy for Suchia. The postorbital- squamosal bar, which separates the upper and lower temporal fenestrae at the rear part of the skull, is short. This has the effect of making the lower temporal fenestra triangular in shape. However, Sereno also noted that this feature was not present in Prestosuchus, which he excluded from the group.

In Romanian, rhotacism shifted intervocalic l to r and n to r. Thus, Latin caelum ‘sky; heaven’ became Romanian cer, Latin fenestra ‘window’ Romanian fereastră and Latin felicitas ‘happiness’ Romanian fericire. Some northern Romanian dialects and Istro-Romanian also changed all intervocalic to in words of Latin origin. For example, Latin bonus became Istro-Romanian bur: compare to standard Daco-Romanian bun.

Only Megalocephalus is known to share this brassicate patch with colosteids. The mandibles were also unique in the fact that they possessed a single elongated hole along their inner surface, known as an exomeckelian foramen (or a meckelian fenestra). Earlier stegocephalians like Ichthyostega possessed a subtle slit in the mandible, while most later groups had a series of smaller, well-defined holes.

The postorbital is incomplete, but the postorbital and suborbital bars are thinly shaped. The pineal foramen is larger compared to non- varanopseid sphenacodonts and is positioned in the back of the skull. The lateral temporal fenestra of Aerosaurus is larger than other pelycosaurs with its trademark triangular shape. No septomaxilla is evident, but the premaxilla is fragile in comparison to the large naris.

The squamosal is long and narrow and even more so compared to Varanops. The parietal is large with shallow grooves in the supratemporal element. The braincase is well preserved with only the cultriform process missing in all of its external surfaces. The parasphenoid is the largest part of the braincase with some overlap into the basiooccipital to form the "fenestra ovalis".

This leaves the infratemporal fenestra with an arch-like structure, open from below. An incomplete (or absent) lower temporal bar is first seen in the Permian genus Claudiosaurus, and is retained by most other Permian and Triassic diapsids. In many cases, the quadratojugal is lost completely. This loss occurs in several Triassic marine reptiles such as tanystropheids, thalattosaurs, pistosaurs, and plesiosaurs.

Obruchev (1964) and Miles (1969) placed it within the Trematosteidae due to the presence of a postpineal fenestra. Denison (1978) has B. schmidti placed within Selenosteidae, noting that other arthrodires in addition to trematosteids have postpineal fenestrae, as well as similar anatomy of the orbital and suborbital plates, and that its scapulo-coracoid bone is largely identical to those of Pachyosteus and Enseosteus.

Unlike most archosaurs, the nasal and antorbital openings of pterodactyloid pterosaurs merged into a single large opening, called the nasoantorbital fenestra. This feature likely evolved to lighten the skull for flight. In contrast, the bones behind the eye socket contracted and rotated, strongly inclining the rear skull and bringing the jaw joint forward. The braincase was relatively large for reptiles. tapejarids.

The frontal bone has a short front branch. The jugal bone has short branches to the front, in the direction of the maxilla and the nasal bone, and a long narrow upwards branch running towards the postorbital bone. In the outer rear side of the lower jaw an opening is present, the mandibular fenestra. The coronoid process of the surangular bone is low.

The skull preserves an antorbital fenestra, or opening in front of the eyes. The nasal, a bone at the top of the skull behind the nostrils, is relatively long. There is also a small notch at the contact between the premaxilla and the maxilla near the front of the snout. Morrinhosuchus can be distinguished from Mariliasuchus on the basis of several unique features.

Perbrinckia fenestra is a species of freshwater crabs of the family Gecarcinucidae that is endemic to Sri Lanka. the species is categorized as vulnerable by founders due to their single locality where tourist destinations are abundant. The site is Batatotalena Cave in Kuruwita. It is rarely found, and known to live under moist rocks, near water sources and under wet litter.

The ascending (or dorsal) process of the maxilla, which lies in front of the antorbital fenestra, is short and very thin. This process is also uniquely diagonally oriented when seen from above, with its rear edge set inwards from the front edge. The only preserved tooth is thin and serrated. The dentary fragment is incomplete, but seemingly slender and similar to the maxilla.

Restoration of A. gregoryi This small form combines the primitive feature of interpterygoid fenestra with an advanced feature of turtle-like armour. It was about in length, and weighed around . Small dermal ossicles covered the body, while the pattern of armour plates on the back reminiscent of a turtle shell. The tail was further shortened relative to less derived forms.

Ornithischian dinosaurs also showed evidence of homeothermy, while varanid lizards from the same formation did not. Even if T. rex does exhibit evidence of homeothermy, it does not necessarily mean that it was endothermic. Such thermoregulation may also be explained by gigantothermy, as in some living sea turtles. Similar to contemporary alligators, dorsotemporal fenestra in Tyrannosaurus's skull may have aided thermoregulation.

Unlike Ornithosuchus, Dasygnathoides did not appear to have a palatine-pterygoid fenestra as the homologous area of bone is curved outwards. This indicates that, in fact, it is not an ornithosuchan at all. The partial vertebra is found in the same piece of stone as the maxilla. It has a well- developed transverse process and is probably a dorsal or anterior caudal vertebra.

The prefrontal forms a thick eyebrow ridge, possibly as protection from predators. The jugal is complex, with four branches, and forms the anterior and ventral margins of the lower temporal fenestra. The dorsal branch forms a strong pillar behind the orbit, which has a more pronounced crest than other rhynchosaurs. The frontals are very long, and form a dish shape posteriorly.

Despite the large number of specimens of Stegotretus, many are poorly preserved or distorted. Stegotretus is diagnosed by the presence of only two premaxillary teeth and by a large circular fenestra on the palatine. A contact between the maxilla and the quadratojugal and the absence of an entepicondylar foramen on the humerus separate it from the purportedly closely related Pantylus.

More posteriorly on the skull, the parietals lack a sagittal crest. The cranial roof is the narrowest just posterior to the parietal foramen, which is very nearly circular in shape. The temporal crests remain quite discrete throughout the length of the skull. The temporal fenestra have been found with ossified fasciae, giving evidence of some type of a temporal muscle attachment.

This type of tooth position is not seen in any other basal archosaurs. Another characteristic feature of ornithosuchids is their unusual downturned, overhanging snout, seen in Riojasuchus and Venaticosuchus, but not Ornithosuchus. Several other features distinguish ornithosuchids from all other early archosaurs. Ornithosuchus and Riojasuchus both possess a small fenestra, or hole, between the palatine and pterygoid bones of the palate, i.e.

Gwawinapterus beardi is known from a single fossil specimen, consisting only of the front half of a skull (upper and lower jaws). The tip of the snout is rounded and deep with a height of about . The tip is about from the front edge of the largest skull opening, or fenestra. Below this opening the upper jaw is about tall.

Jeholosaurus is an ornithischian, as is shown by its ornithischian four- pronged pelvic structure with a pubis bone pointing downward and backwards, parallel to the ischium, while a forward-pointing prepubic process supports the abdomen. The describers did not assign Jeholosaurus to any family, limiting themselves to a placement as Ornithischia incertae sedis. Using the comparative method, they pointed out some similarities to basal Euornithopoda: a small antorbital fenestra; the foramen on the quadratojugal; a large quadratic foramen; and the absence of an external fenestra in the lower jaw. However, they also noticed more derived euornithopod traits, such as the form of the greater and anterior trochanter of the thighbone, although the premaxilla not reaching the lacrimal, the high jaw joint and the premaxilla being on the same level as the maxilla, were again basal traits.

Labelled diagram showing the skull and its individual bones and openings The skull of Limusaurus was relatively tall and short, roughly half the length of the femur (upper thigh bone). The tip of its jaws was covered by a beak, a feature that was previously unknown in non-coelurosaurian theropods like Limusaurus (the coelurosaurs include the most bird-like dinosaurs). As in most dinosaurs, the skull featured five principal fenestrae (openings): the (bony nostril), orbit, antorbital fenestra (between the nostril and eye), as well as the and (on the top and on the side of the skull's rear, respectively). As in other ceratosaurians, parts of the bony nostril were formed by the maxilla (upper jaw bone); also, the antorbital fenestra was proportionally small, and the rear part of the nasal bone formed parts of the cavity which contained this opening.

The phylogenetic analysis of the original description of Zapatadon found it as a part of a clade that contains to the subfamilies Eilenodontidae (Toxolophosaurus, Eilenosaurus) and Sphenodontinae (Sphenodon, Cynosphenodon), in an unresolved polytomy with the genus Opisthias and this subfamilies, within the family Sphenodontidae. This inclusion is supported by have the great length of the supratemporal fenestra, more than a fourth of the skull length, the single palatine row of teeth and an orbit less than a third of the skull length. Although certain features like the great length of the lower temporal fenestra and the enlarged quadrate-quadratojugal foramen are shared with Sphenodon, suggesting a close relationship, the authors noted that the immature nature of the holotype make a mixture of advanced and primitive characters that do not allow make more clear their phylogenetic relationships.

Restoration of Dimorphodon macronyx, considered a close relative of Parapsicephalus by some authors A 2017 analysis of Parapsicephalus found little support for it being placed in the Dimorphodontia: its skull was comparatively longer; the snout is slightly upturned with outward-projecting teeth, as in rhamphorhynchids; the quadrate is not as vertical; the antorbital fenestra is offset below the nostril instead of being at the same level; and, although the top of the skull is convex in both, the condition in Parapsicephalus is not quite as extreme. Thus, affinities with the Rhamphorhynchidae were considered more probable. Within the Rhamphorhynchidae, unlike the scaphognathines, the antorbital fenestra is more than twice as long as it is tall, and has a concave back margin; the angle of the quadrate is also more than 120°. This implies that Parapsicephalus is a member of the Rhamphorhynchinae.

This is not part of the braincase, but was closely attached to it by several features (see above). The left is better preserved, but disarticulated from the braincase, whereas the right is still attached to the braincase. The palatal ramus is a thin but wide plate of bone, with a ridge reinforcing the medial margin. It also formed the lateral margin of a small interpterygoid fenestra.

Historically, many archosauriforms were described as archosaurs, including proterosuchids and erythrosuchids, based on the presence of an antorbital fenestra. While many researchers prefer to treat Archosauria as an unranked clade, some continue to assign it a traditional biological rank. Traditionally, Archosauria has been treated as a Superorder, though a few 21st century researchers have assigned it to different ranks including DivisionBenton, M.J. (2005). Vertebrate Paleontology, 3rd ed.

The nasal crest side is very rugose with a series of bosses and swellings. The nasal bone contributes to the upper rear part of the depression around the antorbital fenestra. This area shows a number of pneumatic openings or pneumatopores, where diverticula of the air sacks entered the bone. In the front two small foramina are present, more to the rear two large horizontal oval openings.

The pectoral fenestra (an opening enclosed by the scapula and coracoid) is rounded and enlarged. The posterior region of the coracoid is much thinner than the rest of the pectoral girdle. The humerus has a slender, elongated shaft and is another bone with a distinctive shape. The surfaces of the humerus that articulated with the lower arm bones (radius and ulna) have roughly equal lengths.

Rayfield, E.J., Milner, A.C., Xuan, V.B., Young, P.G. 2007. Functional Morphology of Spinosaur "Crocodile Mimic" Dinosaurs. JVP. 27(4):892–901. In some archosaur species, the opening has closed but its location is still marked by a depression, or fossa, on the surface of the skull called the antorbital fossa. The antorbital fenestra houses a paranasal sinus that is confluent with the adjacent nasal capsule.

The skull is rectangular, nearly three times as long as it was high, with an almost rectangular lateral temporal foramen at the back. The large, round orbit (eye socket), the sub- triangular antorbital fenestra and the oval naris are of almost equal size. The lower jaw is shallow, and has a large process extending far behind the jaw joint. The teeth are small and form long rows.

A cladistic analysis showed that Tatankacephalus was a basal member of the Ankylosauridae and relatively closely related to Gastonia. Basal traits include the retention of premaxillary teeth in the front of the upper jaws and a skull opening, the lateral temporal fenestra, that was not covered by the skull armour. A new cladistic analysis performed by Thompson et al., 2011 suggests that Tatankacephalus is a basal nodosaurid.

The section in front of the combined nasal-antorbital fenestra was relatively short. Also unusual was the combination of its toothless jaws and no bony head crest. Lacusovagus was described in 2008 by Mark Witton. The type species is L. magnificens, meaning "grand lake wanderer", in reference to its large size--it is currently the largest pterosaur known from the Crato Formation with an estimated wingspan of .

Io me leva al est, e cuando io me leva, il es die. Io reguarda per tu fenestra con mi oculo brillante como le auro, e io te dice quando il es tempore a levar te. E io te dice: 'Pigro, leva te. Io non brilla a fin que tu resta al lecto a dormir, sed que tu lege e que tu te promena.

On the maxilla, there is a distinct notch that contributes most of the border of a dorsal fenestra. It appeared to be the cranialmost of a series of maxillary foramina that extended across the lateral face of the maxilla. This most likely hinted to cutaneous blood vessels and nerves in that area. This notch is hidden by an overlap of the premaxilla by the maxilla.

The teeth are located entirely anterior to the antorbital fenestra and the snout is especially broad. In some rebbachisaurids, this is taken to such an extreme that the teeth are packed into a row along the transverse portion of the jaw. Several unique features are also noted in the tails of certain diplodocoids. Among the diplodocids, there was a marked increase in the number of caudal vertebrae.

Xilousuchus has a relatively small head and long neck, with a skull length of approximately 25 cm and neck of 45 cm. The skull is fragmentary, but much of the snout and maxilla are present. Only one maxillary tooth has been fossilised. The maxilla has a partially-developed palatal process, and the angle of the dorsal process indicates that Xilousuchus had a large antorbital fenestra.

Rugarhynchos is an extinct genus of doswelliid archosauriform from the Late Triassic of New Mexico. The only known species is Rugarhynchos sixmilensis. It was originally described as a species of Doswellia in 2012, before receiving its own genus in 2020. Rugarhynchos was a close relative of Doswellia and shared several features with it, such as the absence of an infratemporal fenestra and heavily textured skull bones.

Weksler, 2006, p. 37 The subsquamosal fenestra, an opening in the back part of the skull determined by the shape of the squamosal bone, is present.Weksler, 2006, pp. 38–39 The squamosal lacks a suspensory process that contacts the tegmen tympani, the roof of the tympanic cavity, a defining character of oryzomyines.Weksler, 2006, p. 40 There are some openings in the mastoid bone.Weksler, 2006, pp.

Unlike Struthiomimus, the anterior portion of the ilium reaches as far forward as the end of the pubic shaft, and the medial (inner) edge of the third metatarsal is straighter as well. Compared to Ornithomimus, the antorbital fenestra is proportionally shorter. Finally, Rativates is smaller than the large Dinosaur Park ornithomimid (still unnamed as of 2016), and also differs in the anatomy of its unguals (foot claws).

Paludidraco was similar to its close relative Simosaurus, but differed in several important respects. The teeth were pleurodont and it had more than 15 premaxillary teeth, hence the species name multidentatus meaning 'many-toothed'. It had a relatively long snout, but the nostrils were higher up on its head than those of Simosaurus. The upper temporal fenestra is narrow, and the pineal foramen is highly elongated.

Larger allosauroids are found to have a lower CFL muscle-to-body-mass proportion that smaller allosauroids. In addition to body similarities, allosauroids are also united by certain skull features. Some of the defining ones include a smaller mandibular fenestra, a short quadrate bone, and a short connection between the braincase and the palate. Allosauroid skulls are about 2.5 to 3 times longer as they are tall.

Based on what is known of Gorgodon—the squamosal, quadrate, and pterygoid bones of the back of the skull, the maxilla and premaxilla bones that make up the front of the skull, and several teeth—Gorgodon had a relatively large temporal fenestra and a pair large, conical caniniform teeth at the front of the jaw. Other distinguishing features of Gorgodon include the fused connection between the quadrate and squamosal bones and a long transverse process of the pterygoid (a projection extending from the pterygoid bone on the underside of the skull). Olson classified Gorgodon as a very early therapsid because it had a heterodont dentition and large temporal fenestra not seen in the most basal synapsids but present in therapsids. He placed it in the family Phthinosuchidae because its teeth seemed similar to those of Phthinosaurus, an enigmatic therapsid from the Middle Permian of Russia that is most likely a dinocephalian.

Morphologically, the sides of the snout are parallel (unlike the spoon-tipped snouts of Gnathosaurus), most of the mandible is composed mainly of the dentary, and the well-developed retroarticular process is formed by the angular bone like in other ctenochasmatids. There are many long, needle-like, outward-projecting, tightly packed, equally-spaced teeth in the jaws of Liaodactylus, totalling to 152 teeth across both jaws. This is more than Gnathosaurus (128-136), about the same as Gegepterus (150), but much less than Ctenochasma (200-552) and Pterodaustro (almost a thousand). The teeth become shorter towards the back of the jaws, eventually becoming short, peg-like structures at the back of the tooth row; the back of the tooth row corresponding to the front 1/3 of the nasoantorbital fenestra, which is unusual among ctenochasmatids (where the teeth usually stop entirely before the fenestra).

The hind part of the skull roof is only incompletely known, including the hind part of the lacrimal (in front of the eye opening), the postfrontal (above and behind the eye opening), the parietal (at the rear of the skull roof), and parts of a supratemporal (which formed the rear corners of the skull roof). An forward- directed extension of the supratemporal formed the inner-rear edge of the supratemporal fenestra, an opening through the skull roof behind the eyes. The parietal, which would have formed the inner margin of the supratemporal fenestra, had a complex front margin that was interdigitating with either the frontal or postfrontal bones, which are not preserved in the known specimens. Skull and partial neck of SNHM1284-R from below, with interpretative diagram The quadrate bone, which connected to the lower jaw to form the jaw joint, was C-shaped in side view.

Skull, Museo Civico di Storia Naturale di Milano The skull of the holotype is large, compared to the size of the body, and short with very large eye-sockets. This is largely due to its young age. Accordingly, the semi-circular antorbital fenestra, the normally largest skull opening, is short too and smaller than the eye-socket. In front of it two smaller openings are present: the maxillary and promaxillary.

The known posterior part of the skull is high, with an oval orbit and an enlarged infratemporal fenestra, similar to other ceratosaurs. The skull roof is not notably thickened and no cranial ornamentation is present. Restoration Both humeri from the known material are poorly preserved, but show primitive characters. The articular head is slightly rounded, but not a globular shape that is commonly seen in noasaurids and abelisaurids.

A strut of the alisphenoid bone is present, separating two openings in the skull, the masticatory–buccinator foramen and the foramen ovale accessorium. The subsquamosal fenestra, an opening at the back of the skull determined by the shape of the squamosal, is present but small. The squamosal probably lacks a suspensory process that contacts the tegmen tympani, the roof of the tympanic cavity, a defining character of oryzomyines.Weksler, 2006, p.

The first of these is an autapomorphy, or a unique specialization: there are seven pairs of teeth present, all of them placed in front of the nasoantorbital fenestra. The second trait sets Unwindia apart from all other pterosaurs known from the Santana Formation: the teeth are homodont, having the same shape. The other species have more robust teeth in the front of the jaws. Overall, the skull is elongated and flat.

There were triangular nutrient foramina between the plates, each containing the tip of an erupting tooth. The narial fossa (depression) in front of the bony nostril was long, relatively shallow, and less developed than that of Giraffatitan. It contained a subnarial fenestra, which was much larger than those of Giraffatitan and Camarasaurus. The dentaries (the bones of the lower jaws that contained the teeth) were robust, though less than in Camarasaurus.

Leonardo Maiorino and his team used geometric morphometrics to analyze the dimorphism in Protoceratops andrewsi and concluded that there is no difference in male and female structures. Alternatively, Dodson's analysis of structure sizes in large Protoceratops found that they were dimorphic. The length and width of the frill, parietal fenestra, and external nares, the nasal height, the skull width, the orbit height, and the coronoid process height all varied with sex.

Propelanomodon tylorhinus is another dicynodont species that has recently been hypothesized to be a juvenile form of P. moschops. It has a shorter skull, typically shorter than long. Several key cranial features differ within this species when compared to P. moschops’ skulls, which leaves there to be debate among paleontologists about its relationship to Pelanomodon. For example, the temporal fenestra of Propelanomodon point anterposteriorly, rather than being angled slightly laterally.

In Aerosaurus, the teeth were more laterally compressed creating a strong recurved shape. Aerosaurus cranial morphology is distinguishable with its extremely long tooth row, recurved tooth, triangular lateral temporal fenestra. The teeth were so highly curved and compressed that they seem unable to penetrate flesh and the tooth row extended far behind the orbit. The lower teeth were also relatively tiny and such an arrangement suggests Aerosaurus was a carnivore.

The maxilla contains specimens largest teeth and is extended posterior to the center of the triangular lateral temporal fenestra. The maxilla, which is longer compared to other 'pelycosaurs' contacts the quadratojugal in this specimen. The lacrimal is a sheet of bone that covers most of the anterior orbital margin and constricts the front of the orbit. The jugal has a unique lateral serration and narrow postorbital ramus similar to Varanops.

The shape of the soft tissue crest is based on the specimen BSP 1929 I 18 Pterodactylus, like related pterosaurs, had a crest on its skull composed mainly of soft tissues. In adult Pterodactylus, this crest extended between the back edge of the antorbital fenestra and the back of the skull. In at least one specimen, the crest had a short bony base, also seen in related pterosaurs like Germanodactylus.

The alveolar region of the mandible has five teeth preserved in it. The aggregate fossil composed of five individuals is better preserved and showed several new features not present in the holotype. These include a contact between the maxilla and both the prefrontal and the quadratojugals. An anterior inclination of the occiput and the exclusion of the quadratojugal from the temporal fenestra are also clear in this specimen.

Where the premaxilla meets with the naris there is a straight suture instead of the Varanopid typical V shaped one. The jugal and quadratojugal have pinched tubercular ornamentation on the lateral sides. The quadratojugal has the elongated and slender shape distinct to the Varanopids, as well as a slender groove on the dorsal edge. This serves as an attachment for the squamosal, which extends anteriorly under the lateral temporal fenestra.

Like in Huayangosaurus but not Stegosaurus or Hesperosaurus, the nasal fenestra faces anterolaterally, being visible from the front and sides. The naris is longer than wide like in other stegosaurs, and also has a smooth internal surface, so it was most likely a simple passage. The maxilla is roughly triangular, as in most other thyreophorans. The tooth row is horizontal in lateral view, and in ventral view it is sinuous.

Anais, Academia Brasileira de Ciências, 61: 319–333. while Kischlat (2000) considered it to be a rauisuchian. Irmis, Nesbitt and Sues (2013) stated that they "could not find any crocodylomorph character states preserved in the holotype specimen". Based on the presence of an antorbital fenestra the authors assigned Barberenasuchus to Archosauriformes, but stated that without further preparation and study it is not possible to assign it to any specific archosauriform group.

The triangular teeth were closely spaced, interlocked, and formed a "razor-edged" outline. The lower jaw also had a tooth-like projection that occluded with the teeth. The skull had a very large naso- antorbital opening (which combined the antorbital fenestra and the opening for the bony nostril) and a slender eye socket. Some of the vertebrae were fused into a notarium, to which the shoulder blades connected.

On the thumb claw the raised attachment point for the tendon of the extensor muscle is bordered by deep grooves for ligaments. The large skull opening in the snout, the fenestra antorbitalis, is positioned in a depression which reaches the side of the nasal bone. There are at least five pairs of conical teeth in the front of the lower jaws. These teeth are hollowed-out at the inside.

Coeruleodraco is an extinct genus of choristoderan that lived in China during the Late Jurassic (Oxfordian).Coeruleodraco is significant as the most complete Jurassic choristodere taxon ever found worldwide, considering that Cteniogenys is based on fragmentary remains. Although similar to Philydrosaurus in its proportions and postcranial characters, it is distinct in retaining several apparently plesiomorphic characters, including a short snout, paired external nares and an open lower temporal fenestra.

The rear edge of each upper temporal fenestra was formed by the squamosal bone, which was ornamented with small spines. The postcranial skeleton was very similar to that of Philydrosaurus. The neck was short, and its vertebrae had low, swollen neural arches (upper portions). There were six or seven vertebrae in the neck, 16 in the torso, three in the hip, and more than 24 in the tail, which is incomplete.

The higher back of the lower jaw seems to show a much larger opening, but this is an artefact caused by the original inexpert preparation damaging the thin bone surface of an extensive mandibular fossa. A real and much smaller external mandibular fenestra is present in front of this. Neither the lower jaw nor the upper jaw form cutting edges. The cervical vertebrae are elongated with low spines.

Immediately below this bar, there is a horizontal groove, or transverse sulcus. Further behind, the upward-projecting dorsal process is wider and angled further backwards than Rhabdodon, and larger than Zalmoxes. From the base of this process, a "wing" extends backwards to articulate with the jugal bone. Also at the base of the dorsal process is a small triangular projection delimiting the back of the antorbital fenestra, which is shorter than Rhabdodon.

Compared to Camarasaurus, the teeth at the front of the jaw are more pointed and have taller crowns. There are no well-developed vertical ridges on the outer surface of the teeth, in contrast to its closest relative Moabosaurus. In Mierasaurus, the skull roof is overall flattened, lacking any convexities. Unlike more derived sauropods but also seen in Turiasaurus, the frontal bone of Mierasaurus participates in the margin of the supratemporal fenestra.

The frontal would have formed the upper edge of the orbit (eye socket), but it is poorly preserved. The long front branch of the slender jugal forms most of the lower edge of the orbit. The shorter rear branch of the jugal would have formed part of the lower edge of the infratemporal fenestra. The quadrate is straight, has a triangular pterygoid flange on its front edge, and generally resembles that of Euparkeria.

Kembawacela broadly resembled other cistecephalids in size and shape. It was a small dicynodont (skull length roughly long along the base) and had a highly specialised body plan for digging. Kembawacela is known from skulls, lower jaws and various pieces of postcrania, including parts of the pelvis, femur, ulna and various vertebrae. Its skull is typical for cistecephalids, with a broad head and large temporal fenestra with a very short, tapered snout.

The main body of the lacrimal is a rounded square with both faces of the bone are concave. Its contact with the nasal is rather limited in both species. The oval-shaped antorbital fenestra is small, being only 9% the length of the eye socket; its presence is unique to both species of the genus among atoposaurids. Meanwhile, the eye socket is large and oval, being 54% longer than it is tall.

Life restoration Pampadromaeus was a small bipedal animal. It shows a mosaic of basal and derived traits. It differs from other sauropodomorphs by a combination of characters. Some of these are shared with members of the Theropoda: the premaxilla is pointed downwards forming a subnarial gap with the maxilla and the anterior-most teeth are unserrated; in the location where with theropods the fenestra promaxillaris is positioned, a small depression is present.

The premaxilla shows a distinctive opening below and in front of the nostril. The rear upper process of the premaxilla touches the upper rim of the fenestra antorbitalis but not the front process of the lacrimal; both bones are separated by the nasal bone. The parietal approaches the frontal bone in length. At the fourth and fifth neck vertebrae, the rear edge of the vertebral centrum forms a straight line between the postzygapophyses.

Another unique trait it had among sauropodomorphs was a closed supratemporal fenestra. The nasal openings, the bony nostrils, were elongated. Though the nasal bones are not completely known, it appears the front margin of the bony nostril was closer to the snout than in other diplodocoids. The snout was also proportionately shorter, and the tooth row was not at all prognathous, the snout tip not protruding relative to the remainder of the tooth series.

The postorbital bone has a small secondary process, jutting into the upper hind corner of the eye socket. The outer side of the main body of the postorbital is hollowed out. In the lower jaw, the external mandibular fenestra, the main opening in the outer side, is mainly located in the surangular. According to a 2018 study, Yutyrannus had a simple hyoid structure, indicating it had a flat tongue, like a crocodile.

Unaysauridae was defined by Müller et al. (2018) as the most inclusive clade including Unaysaurus tolentinoi, but not Plateosaurus engelhardti nor Saltasaurus loricatus. Members of Unaysauridae are diagnosed by a substantially expanded cranial part of the medial condyle of the astragalus, as well as a promaxillary fenestra. Unaysauridae is sister to Plateosauria, more derived than Nambalia, Thecodontosaurus ISI R277, Pantydraco, and Efraasia.Rodrigo Temp Müller; Max Cardoso Langer; Sérgio Dias-da-Silva (2018).

Lecuona and colleagues added two synapomorphies of Gracilisuchidae to those listed by Butler: the absence of the jugal's contribution to the postorbital bar behind the eye socket, and the articulations with the fibula and astragalus forming a continuous structure on the calcaneum. They also removed the original character involving the calcaneal tuber. Finally, they added one synapomorphy uniting Gracilisuchus and Yonghesuchus: the absence of the postorbital's contribution to the border of the infratemporal fenestra.

Romer noted that Gracilisuchus was the smallest and oldest known member of the group to date, and accordingly had a fairly basal morphology (notwithstanding supposedly aberrant traits such as the partial closure of the infratemporal fenestra). However, he had reservations regarding Walker's identification of ornithosuchids as dinosaurs, noting basal archosaur traits such as the closed acetabulum, osteoderms, and crocodile-normal ankle. Thus, he considered the supposedly carnosaurian features to be products of convergence.

A large part of the snout is occupied by long bony nares. Below them a small triangular skull opening, the fenestra antorbitalis is present. Reflecting the more shallow snout, the teeth of Campylognathoides are also short and not at all laniaries or fang-like as in the markedly heterodont Dorygnathus. They are conical and recurved but have a broad base with the point bevelled off from the inside forming a sharp and strong cutting surface.

Only a few species, such as Gobipteryx minuta, were fully toothless and had beaks. They also had simple quadrate bones, a complete bar separating each orbit (eye hole) from each antorbital fenestra, and dentaries (the main toothed bones of the lower jaw) without forked rear tips. A squamosal bone is preserved in an indeterminate juvenile specimen, while a postorbital is preserved in Shenqiornis and Pengornis. In modern birds these bones are assimilated into the cranium.

Heilmann's comparative illustrations of the feet and scale shields of various extant birds and reptiles He begins the section with an analysis of the temporal opening found in the skull of many extant birds. After a thorough comparison, he rejects the notion, which was common at the time, that this temporal opening was homologous with the supratemporal fenestra in reptiles. Instead, he concludes that it is a recent feature.Heilmann (1926) pp. 97–100.

The authors established some unique traits. The rostral, the bone core of the snout beak, curves downwards and has an arched keel on its top with a bump on the front. In front of the tooth row the upper jaw rim is over its total length concave in side view. The skull opening, the antorbital fenestra, is twice as long as it is tall and has a pointed rear, below the eye socket.

The teeth rows stretch from the very front of the head until the back edge of the fenestra nasoantorbitalis. They are associated with oblique cellular structures visible in the bone of the upper and lower jaws, the nature of which has not been determined. Hollow structures, reinforced by struts, can also be seen in the parietal crest and the vertebrae. The fourth cervical is 7.25 times as long as it is tall.

Much of the skull was occupied by very large naso-antorbital fenestrae (openings which combine the antorbital fenestra and the bony nostril). Unusually, this opening extended past the jaw joint and the back of the mandible. The orbit (eye socket) was reclined and slender, and was capped at the front by a tuberosity. The hind part of the skull was relatively tall, and the skull table bore a low crest or ridge at the front.

Material now referred to Stegotretus was first described (in brief) by Eberth & Berman (1983). It was formally named by Berman et al. (1988). The genus name comes from the Greek stegos ('roof') and tretos ('perforated') to refer to a large fenestra found on the palatine bone. The species name, S. agyrus, is said to be derived from Greek agyrus ('gathering' / 'crowd') in reference to the concentration of all known specimens in a small area.

The jaw was originally suggested to be a sutureless fusion of the premaxilla and maxilla of a reptile. Each upper jaw holds at least 26 teeth, eleven or twelve of them below the fenestra; the front of the tooth row has not been preserved and the fossil is broken at its end. The teeth are closely packed. The tooth crowns are small, tall and wide, flattened, and triangular with slightly curved edges.

The ilium is short and tapers towards the rear. The top edge of the pubis is large and rounded while the back edge is arched, creating a large thyroid fenestra between the pubis and ischium. The ischium is larger than the pubis and has a bony spur which could have connected to tail muscles. The femur is S-shaped but the finer details of its structure (as well as the structure of the tibia and fibula) are poorly developed.

Shartegosuchids can also be diagnosed by the position of the teeth in their lower jaws, which are never found behind the mandibular fenestrae (holes found near the back of the jaw). The edges of the teeth are denticulated, or ridged. The shape and position of several bones of the skull, including the frontal, nasal, lacrimal, and quadrate, are also distinctive. Unlike most other archosaurs, shartegosuchids lack an antorbital fenestra, an opening in the skull in front of the eyes.

Restoration of Acanthostega In the tetrapod and higher clades from the lower-middle Famennian there are several defining changes on the basis of anatomy of Ichthyostega, Tulerpeton, and Acanthostega. In the cranium, there is a stapes derived from the hyomandibular of fishes; a single bilateral pair of nasal bones, and a fenestra ovalis in the otic capsule of the braincase.Lebedev, O. A., & Coates, M. I. (1995). The postcranial skeleton of the Devonian tetrapod Tulerpeton curtum Lebedev.

Heleosuchus is suggested as being either an early diapsid reptile, not closely related to other lineages, or as being an aberrant and primitive lepidosauromorph. Heleosuchus shares the hooked fifth metatarsal found in some other diapsids, such as primitive turtles (Odontochelys), lepidosauromorphs, and archosauromorphs, but it also resembles "younginiform"-grade diapsids in its gross morphology. Heleosuchus may also share a thyroid fenestra with these higher diapsid reptiles as well, but the identity of this feature is disputed.

The upper surface of a typical iguanodontid skull has a convex curve that extends from the snout to just past the orbit, where the skull flattens out to form a roughly level plane directly above the braincase. The antorbital fenestra, an opening in the skull anterior to the eye sockets, is reduced in size in iguanodontids. Their maxillae are roughly triangular, fairly flat, and sport thickened bony walls. An elongated maxilla is characteristic of the family.

The skull of Duerosuchus is around long. The length of the entire animal is estimated to have been around . This estimation is based on the size of the body relative to the skull in similar crocodilians where the body length is known. The holotype skull, known as STUS 14.133, is missing some bones such as those surrounding the infratemporal fenestra on the back side of the skull and the nasal bone along the midline of the snout.

Size comparison While oviraptorids were generally one to eight metres in body length, Yulong was described as "chicken-sized" by its describers. Most of the Yulong individuals had a total body length of a quarter to half a meter, making them some of the smallest known oviraptorids. The describing authors established some diagnostic traits. The front upper corner of the fenestra antorbitalis and the rear upper corner of the bony nostril are positioned at about the same height.

These trabeculae may also be thought of as the rims of two large foramina that incise the posterior edge of the sternum, and extend almost its whole length. Tinamous have a proper semicircular furcula, with no trace of a hypocleidium.Eyton, T.C. (1867) There is an acute angle between the scapula and coracoid, as in all flying birds. The pelvis has an open ilio–ischiatic fenestra that incises the posterior edge between the ilium and ischium, as in all paleognathes.

Another seemingly non-archosaurian trait reported in Turfanosuchus is the fact that its internal carotid arteries enter the braincase from below, rather than from the sides as in almost all other archosaurs (including Gracilisuchus and Yonghesuchus). However, this trait is also known to occur in other crown-archosaurs like Arizonasaurus, Qianosuchus, and Silesaurus. Otherwise, the braincase is generally similar to other archosaurs. The lower jaw was slender, with an elliptical hole known as a mandibular fenestra.

Restoration In 2015, Jack Horner established some distinguishing traits. Two of these are autapomorphies, unique derived characters. The crest formed by the nasal bones is flat and paddle-shaped in adult individuals and largely or totally overhangs the supratemporal fenestrae. The rear edge of the prefrontal bone overgrowths the frontal bone and more to the rear is oriented inwards and downwards to support the base of the crest and contribute to the edge of the supratemporal fenestra.

Further back, immediately in front of the nasoantorbital fenestra, the palatal ridge became a strong, blunt, convex keel. This convexity fit into the symphyseal shelf at the front end of the lower jaw, and they would have tightly interlocked when the jaws were closed. The palatal ridge ended in a strongly concave area unique to this species. The postpalatine fenestrae (openings behind the palatine bone) were oval and very small, differing from those of related species.

Early in their evolution, diapsid reptiles evolved a lower temporal bar which was composed of the quadratojugal and jugal. The lower temporal bar forms the lower border of the infratemporal fenestra, one of two holes in the side of the head and a hallmark of a diapsidan skull. However, many diapsids, including modern squamates (lizards and snakes), have lost the lower temporal bar. Crocodilians and rhynchocephalians (the latter represented solely by the tuatara, Sphenodon) retain a quadratojugal.

Sauropsids, the group containing reptiles and birds, had completely lost the contact between the quadratojugal and maxilla. In diapsids, the quadratojugal and jugal form the lower temporal bar, which defines the lower border of the infratemporal fenestra, one of two holes in the side of the head. In early diapsids such as Petrolacosaurus and Youngina, the quadratojugal is long as in amphibians, early synapsids, and "anapsid" reptiles. It forms most of the length of the lower temporal bar.

The skull belongs to a large animal, with the preserved portions measuring and an estimated complete length of approximately , resembling those of other basal loricatans. The material largely consists of the skull roof, including the nasals, maxilla and part of the premaxilla. The snout is narrow and pointed, with a tall maxilla. Only a small, rounded front portion of the antorbital fenestra is preserved, though it was likely triangular based on the height of the skull.

Sereno and Wilson 1998 p. 46 The ventral process of the postorbital bone is broader when viewed from the anterior when compared to the width when viewed from the lateral side.Sereno and Wilson 1998 p.46-47 Neosauropods lack a point of contact between the jugal bone and the ectopterygoid arch. Instead, the ecterpteryoid arch abuts the maxilla, anterior to the jugal. The external mandibular fenestra, present in prosauropods and some basal sauropods, is entirely closed.

Fenghuangopterus was similar to other scaphognathines in its short, blunt skull with a large antorbital fenestra, and widely spaced, vertically oriented teeth (as opposed to the horizontally- oriented teeth of other rhamphorhynchids). Like all known rhamphorhynchids its tail was stiffened by long vertebral extensions. The primary differences between Fenghuangopterus and other scaphognathines reside in its more numerous teeth — eleven in the upper jaw — which extended further back in the jaw than with its relatives, and its earlier time period.

The occipital region of Limnoscelis was relatively flat, similar to that of some basal synapsids. Limnoscelis had a single occipital condyle. Limnoscelis had an anapsid skull fenestration pattern, lacking temporal fenestrae. However, the supratemporal of Limnoscelis has been pushed posteriorly and ventrally, creating a “line of weakness” between the supratemporal, postorbital, and squamosal bones. This “line of weakness” has been proposed to be a precursor to the synapsid temporal fenestra, although this hypothesis has been challenged.

The oval window (or fenestra vestibuli) is a membrane-covered opening from the middle ear to the cochlea of the inner ear. Vibrations that contact the tympanic membrane travel through the three ossicles and into the inner ear. The oval window is the intersection of the middle ear with the inner ear and is directly contacted by the stapes; by the time vibrations reach the oval window, they have been amplified over 10 timesMoore and Dalley. Clinically Oriented Anatomy.

9 no. 2. p. 125-136. It is unlikely that Kayentavenator is actually congeneric with Megapnosaurus kayentakatae due to the number of tetanuran characters that Kayentavenator possesses and M. kayentakatae lacks, such as the pubic fenestra and a sharp ridge on the medial side of the tibia. A cladistic analysis of the remains showed Kayentavenator to lie outside of Coelophysidae, and was closer to Allosaurus. This would make Kayentavenator the oldest known tetanuran from North America.

However, these characteristics have been observed in various non- amniote tetrapods, so they do not signify its status as an amniote. The lower jaw retained a few plesiomorphic characteristics. For example, the inner edge of the mandible possessed three coronoid bones. The mandible also retained at least one large hole along its inner edge known as a meckelian fenestra, although this feature was only confirmed during a 2005 re-investigation of one of the Cutler Formation specimens.

Dromaeosaurid fossil displayed in Hong Kong Science Museum. Dromaeosaurids are diagnosed by the following features; short T-shaped frontals that form the rostral boundary of the supratemporal fenestra; a caudolateral overhanging shelf of the squamosal; a lateral process of the quadrate that contacts the quadratojugal; raised, stalked, parapophyses on the dorsal vertebrae, a modified pedal digit II; chevrons and prezygapophysis of the caudal vertebrae elongate and spanning several vertebrae; the presence of a subglenoid fossa on the coracoid.

The basipterygoid processes themselves were also thinner than those of Riojasuchus, and they are separated from each other by a wider gap. The palate (roof of the mouth) was generally similar to that of Riojasuchus. The mandible (lower jaw) was robust, proportionally more similar to Ornithosuchus rather than Riojasuchus. On the other hand, the mandibular fenestra (a large hole on the side of the jaw) was elongated and proportionally more similar to that of Riojasuchus rather than Ornithosuchus.

F. rhopalophylla in flower F. rhopalophylla subsp. aurantica The only species currently recognised in this genus is Fenestraria rhopalophylla. Each leaf has an epidermal window, a transparent window-like area, at its rounded tip, it is for these window-like structures that the genus is named (Latin: fenestra). Fenestraria rhopalophylla appears very similar to Frithia pulchra, though the leaves are a slightly different shape and F. rhopalophylla has yellow flowers, compared to the pink flowers of F. pulchra.

The discovered skull has unusually ethmoid cartilages which include large hemispherical nasal capsules. The nasal capsules are bridged by an internasal groove. Each capsule roof is shorter than the floor, suggesting that, unlike many sharks, the narial openings were directed slightly dorsally. The capsule wall openings include a canal for the olfactory nerve (nerve I), a foramen for the profundus nerve (nerve V), and an opening in the floor, which resembles the subnasal fenestra of Doliodus.

In the wake of this restudy, the specimen was recognized as a new taxon, which was named Australohyris smithi by Sean P. Modesto, Diane M. Scott, and Robert R. Reisz in 2009. The generic name translates to "southern opening" in recognition that it supports the hypothesis that parareptiles originated in Gondwana and went through a phase of evolution where they possessed a temporal fenestra, an opening in the skull behind the eyes. The specific name honors Robert Smith.

These include a second dorsal ridge scale (from which the Latin species name, coronatus, is derived), presence of olfactory fenestra on premaxilla, posterodorsal process on cleithrum, and several others. The largest measured recovered specimen was 97 mm (3.8 in), and the smallest was 30 mm (1.2 in), which represented a subadult specimen. Polazzodus, being a low-bodied pycnodont, is most similar morphologically to Pycnodus and Tergestrinia, though its body shape is more oval than these genera.

Close up of the skull According to Pu et al. 2013, Jianchangosaurus can be distinguished based on the presence of 27 tightly packed maxillary teeth; the dorsal border of the antorbital fenestra is formed by the maxilla, nasal, and lacrimal, but with the majority of the border formed by the nasal; there is no participation of jugal in the margin of the antorbital fenestra; a short diastema is present in the anterior tip of the dentary; dentary teeth have a concave labial surface and a convex lingual surface (this condition is present for all except six anterior teeth); the lack of prominent hypapophyses in the anterior dorsal vertebrae; the anterior caudal centra have an oval cross section and the articular facet is as tall as it is wide; the presence of weakly curved manual unguals with weak flexor tubercles positioned ventral to the articular facet; the ilium is shallow and elongated; the ridge bounding the cuppedicus fossa is confluent with acetabular rim; and there is extensive contact between the pubic apron.

The bar is broad at the front just behind the eyes and at the back of the skull, while the middle is pinched inwards between the two temporal fenestra, creating the characteristic 'X'-shape. The eponymous pineal foramen on the roof of the skull is also proportionately "enormous" ( long), implying Ufudocyclops had a very well-developed parietal "third eye". The pineal foramen also has a characteristic depression behind it on the intertemporal bar that is deep and triangular in shape.

It was found by Johnny Allen Byers (Ted & Mary's favorite boy) and J. Maurice in May 1990. The specimen includes the lower jaw and a variety of postcranial elements, such as vertebrae, limb bones, shoulder and hip bones, and bony armor. The lower jaw was elongate and slender, with the two halves joined from the tip to the sixteenth teeth, and there was no mandibular fenestra. Yuong–Nam Lee named Woodbinesuchus in 1997, naming the type species W. byersmauricei to honor the discoverers.

In the original description of Tambachia, Sumida et al. (1998) concluded that Anconastes was the closest relative of Tambachia. Characteristics that supported this relationship included the absence of an internarial fenestra (which is also seen in dissorophids, but was interpreted as a convergent trait), the reduction of the suborbital process of the lacrimal, and a contribution to the ventral orbital rim (the rim of the eye socket) by the maxilla rather than the palatine. Below is a cladogram modified from Sumida et al.

The specific name means "toothless" in Latin. Jaws of the holotype The genus is based on holotype CAD-01, a nearly complete skeleton with partial skull. The skull is toothless and relatively long, with a straight and very pointed beak, and a large hole where the antorbital fenestra is joined with the nostrils. The eye sockets are small, and there is no crest along the lower jaw as seen in ornithocheiroids, although a short projection was present at the back of the skull.

The skull of Plateosaurus is small and narrow, rectangular in side view, and nearly three times as long as it is high. There is an almost rectangular lateral temporal foramen at the back. The large, round orbit (eye socket), the sub-triangular antorbital fenestra and the oval naris (nostril) are of almost equal size. The jaws carried many small, leaf-shaped, socketed teeth: 5 to 6 per premaxilla, 24 to 30 per maxilla, and 21 to 28 per dentary (lower jaw).

Foam skeletal restoration The holotype skull of Guidraco has a length of . It is very elongated with a hollow profile but not very pointed as the upper edge and the line of the jaw run nearly parallel over most of their length. The ensuing relative robustness of the snout is reinforced by a short main skull opening, a fenestra nasoantorbitalis with just a quarter of skull length, and a lower jaw equalling the rostrum in depth. The snout lacks a crest.

Further above, the lacrimal is joined by the long and slender descending branch of the three-pronged postorbital, which is convex in its upper third. From above, the forward-directed branch of the postorbital is offset from the backward-directed branch, being separated by a small recess. The frontals appeared to have been long and large, forming most of the top of the skull. The antorbital fenestra of Shuangbaisaurus is large, occupying roughly one third the length of the skull.

The antorbital fossa, the basin surrounding the antorbital fenestra, was deep. The premaxilla has a characteristically long posterodorsal process that articulates with the nasals, excluding the maxilla from the external naris, which tapers posteriorly. A narrow slit was identified between the premaxilla and maxilla, as in other loricatans, however this feature is likely to be from postmortem distortion rather than anatomical. An unusual feature found in Luperosuchus is the tall, mediolaterally compressed crest that sits on the front of the snout.

Window is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. Window replaced the Old English eagþyrl, which literally means 'eye-hole,' and 'eagduru' 'eye-door'. Many Germanic languages however adopted the Latin word 'fenestra' to describe a window with glass, such as standard Swedish 'fönster', or German 'Fenster'. The use of window in English is probably because of the Scandinavian influence on the English language by means of loanwords during the Viking Age.

The lower jaw as a whole is laterally compressed and curved anteroposteriorly, so that the narrow ventral surface is convex and the jaw forms a half-moon shape. The mandibular fenestra is elliptical, and does not excavate the dentary noticeably, rather remaining between angular and surangular. The dorsal end of the dentary extends posteriorly around part of the surangular; the outer surface of the dentary is entirely smooth. The surangular has a triangular cross-section and is tallest in the anterior portion.

The skeleton consists of a skull, a hyoid bone, spine and ribs though a few species retain a vestige of the pelvis and rear limbs in the form of pelvic spurs. The bar under the second fenestra has also been lost and the jaws have extreme flexibility allowing the snake to swallow its prey whole. Snakes lack moveable eyelids, the eyes being covered by transparent "spectacle" scales. They do not have eardrums but can detect ground vibrations through the bones of their skull.

The nares are expanded and elongated and almost collide with the antorbital fenestrae, meaning that the septum (bony wall) between them is thin and lightweight. Unusually, the jugal forms no part of the border of the antorbital fenestra. Each orbit had a large and well-developed sclerotic ring in it, which would have reinforced the eyeball under pressure when Qianosuchus was diving. The frontal bones have deep fossae (depressions) on their upper surface, which stretch backwards to the sutures with the parietals.

The jugal below and behind the orbit bears the same shape as in hadrosaurids, with a high rear process, and articulated with the quadratojugal and quadrate that are also very similar to more derived taxa. As in other ornithopods, the is a tri- radiate bone surrounding sides of the orbit, and . Contact between the postorbital and the excludes the flattened and wide from the supratemporal fenestra. In Ouranosaurus and related taxa the are small, and articulates with the broadened and textured lacrimal.

Shansisuchus (meaning "Shansi Province crocodile") is an extinct genus of archosauriform reptile belonging to the family Erythrosuchidae that lived during the Middle Triassic in what is now China. The first fossils of Shansisuchus were discovered from the Ermaying Formation of Shansi Province in 1964 by Chinese paleontologist Yang Zhongjian. Like other erythrosuchids, Shansisuchus was a large-bodied carnivore with a large, deep skull. Shansisuchus is unique among early archosauriforms in having a hole in its skull called a subnarial fenestra.

Front view of skull This whale was similar in appearance to the living Balaenopteridae, although it was considerably smaller in size: the skull barely exceeded one meter in total length, while the entire animal reached around six meters. Considered nowadays to be a primitive member of the Mysticeti, already equipped with baleen, Titanocetus was a carrier of both modern (i.e. the rostrum, wide and flat) and ancestral characters (i.e. the squamosal and parietal bones, which occupy part of the temporal fenestra).

Caudipteryx had a short, boxy skull with a beak-like snout that retained only a few tapered teeth in the front of the upper jaw. It had a stout trunk, long legs and was probably a swift runner. Caudipteryx has a short tail stiffened toward the tip, with few vertebrae, like in birds and other oviraptorosaurs. It has a primitive pelvis and shoulder, and primitive skull details in the quadratojugal, squamosal, quadrate, jugal, and mandibular fenestra (in the cheek, jaw, and jaw joint).

The antorbital fenestra would have been located in front of the eye opening, although this region is not preserved. An unusual feature were small openings seen on the backside of the skull, the so-called parietal openings or fontanelles. In other tetrapods, these openings are usually seen only in juveniles and would close as the individual grows. Skull features shared with Dicraeosaurus but absent in most other sauropods included the fused and the notably long , bony extensions connecting the with the .

The pattern of pitting and holes on the outer surface of the dentary also resembles those taxa. The tooth row is edged by a medial groove connecting a series of replacement pits; above the groove the bone is inset similar to the case in Silesaurus, Eucoelophysis, and Technosaurus. Kwanasaurus is the only silesaurid to preserve data on the mandibular fenestra. This hole in the jaw was triangular, edged from below by a posteroventral process of the dentary which also overlapped a partial angular.

The procoracoid foramen (or coracoid foramen, coracoid fenestra) is a hole through the process at the front of the coracoid bone, which accommodates the supracoracoideus nerve. In some groups of birds it may be present as a notch, or incisura; or the notch may be partially or weakly closed with bone. In other groups the feature is completely absent. The foramen is generally present in birds of prey, but it is absent in most Accipiter hawks that have been studied.

Diagnostic features of Toipahautea include: massive periotic; well-developed superior process of the periotic; prominent elongation of dorsomedial margin of the internal acoustic meatus; prominent fissure between the fenestra rotunda and the aperture for the cochlear aqueduct; small medial posterior sulcus; the presence of the anteroexternal foramen; the presence of the sigmoidal cavity; the presence of the elliptical foramen; horizontal sigmoidal cleft far anterior than the anterior margin of the sigmoidal process; posteromedial margin of the bulla orienting slightly anteromedially.

Skull of an undescribed species known as "Ronaldoraptor" The most characteristic feature of this group is the skull structure. Oviraptorids had short snouts and very deep mandibles. Some taxa (Oviraptor, Citipati, Rinchenia) had a midline crest on top of the skull, resembling that of a cassowary. Other distinguishing characteristics include a bony spike intruding on the mandibular fenestra, nostrils placed very high and far back on the snout, an extremely thin bony bar beneath the eye, and highly pneumatized skull bones.

Some large theropods share with Smok the deep depressions of the basisphenoids in the braincase. Similarities with rauisuchians include a triangular antorbital fenestra and a connection between the ectopterygoid and jugal bones of the skull that is split into two projections. The hip of Smok has a ridge on the lateral surface of the ilium above the acetabulum. This ridge is a defining characteristic of rauisuchians, forming a buttress over the femur and giving these animals a pillar-erect stance.

A pristinely preserved three-dimensional braincase of Ventastega has been discovered, and closely resembles the braincase of Acanthostega, except Ventastega had a uniquely large and bi-lobed nerve foramen on the anterior face of the prootic, along with a orbit-temporal region immediately dorsal to the basipterygoid processes. Shared features between the two taxa were the shape of the prootic region and its location to the ventral cranial fissure and fenestra vestibuli, along with the basipterygoid processes and laterally open post-temporal fossae.

Australothyris is an extinct genus of basal procolophonomorph parareptile known from the Middle Permian (middle Capitanian stage) of Tapinocephalus Assemblage Zone, South Africa. The type and only known species is Australothyris smithi. As the most basal member of Procolophonomorpha, Australothyris helped to contextualize the origin of this major parareptile subgroup. It has been used to support the hypotheses that procolophonomorphs originated in Gondwana and ancestrally possess temporal fenestrae, due to its large and fully enclosed temporal fenestra and South African heritage.

Both the genus Globidens and Prognathodon (sometimes classified as a globidensin, though most often not) have adaptations to a powerful jaw musculature. The ratio between the length of the supratemporal fenestra and the total length of the skull has previously been used as an improvised measurement for mosasaur bite force, and is quite high in these genera (0.27 in Globidens dakotensis and 0.22 in Prognathodon overtoni and P. saturator) compared to other mosasaurs like Mosasaurus hoffmannii (with a ratio of 0.19).

The shovel-like shape was similar to that of the common seagull, and the lower beak may have had a shape similar to that of this bird. The retroarticular process at the back of the jaw (where jaw muscles attached that opened the beak) was well developed and consisted mainly of the angular bone. The surangular was the largest bone of the lower jaw, which is usual in theropods. The mandibular fenestra, a sidewards-facing opening in the lower jaw, was elongated and comparatively small.

Between the frontals and the parietals the skull roof over a limited distance has not closed yet, resulting in a conspicuous diamond-shaped opening, a fontanelle that was first mistaken for damage inflicted on the fossil during the first preparation. On its inner side the supratemporal fenestra has no depression, being bounded by a high edge of the parietal. The jugal has no front vertical branch towards the lacrimal. The quadrate bone has on its front edge a large wing-like expansion, touching the pterygoid.

Reconstructed Theiophytalia skull mounted on a Camptosaurus skeleton cast, Museo Nacional de Ciencias Naturales, Madrid Detailed comparisons by Brill and Carpenter (2006) also showed that the skull differed in a number of key features from that of Camptosaurus, namely: a longer, heavier, and more rugose snout; a wider dorsal process on the maxilla; a proportionally smaller antorbital fenestra; and stouter quadrate, with a bulbous articulation for the lower jaw. Compare the skull image with that of Camptosaurus. Therefore, they put it into its own genus and species.

Skeletal restoration showing known elements Among its sister taxa, Linheraptor is believed to be most closely related to Tsaagan mangas. Linheraptor and Tsaagan were intermediate between basal and derived dromaeosaurids. The two share several skull details, among which a large maxillary fenestra — an opening in the maxilla, an upper jaw bone — and lack various features of more derived dromaeosaurids such as Velociraptor. Senter (2011) and Turner, Makovicky and Norell (2012) argue that Linheraptor exquisitus is a junior synonym of Tsaagan mangas, but Xu, Pittman et al.

The back of the bone bears a small notch in K. langenbergensis and a general concavity in K. guimarotae that slightly exposes the underlying supraoccipital. The postorbital bears two branches that join with a gentle curve, separated by an angle of 130° in K. langenbergensis. The supratemporal fenestra is roughly square in K. guimarotae but has a thinner back end in K. langenbergensis. In both species, the maximum distance between the supratemporal fenestrae is about a third of the total width of the top of the skull.

This reinterpretation means that the orbit had a rounder and much less unusual shape than that of Bartholomai's original reconstruction, as the actual postorbital bone was positioned further forward on the skull. Unfortunately, the postorbital is mostly lost, with only a small sliver of bone still present in the specimen. Nevertheless, this postorbital sliver can be seen to contact a supratemporal fenestra, omitting the preserved postfrontal bone from contact with the hole. This reinterpretation has several implications for bone identifications in the rest of the skull.

M. cornalianus restoration Many specimens of Mixosaurus cornalianus have been found from the Middle Triassic of Monte San Giorgio and the Tessin areas on the border of Italy and Switzerland. Mixosaurus cornalianus is the only Triassic ichthyosaur for which completely articulated skeletons have been found. Many specimens have been collected but Mixosaurus cornalianus is not well studied, this is because all of the known specimens have been compressed during the preservation process. Mixosaurus cornalianus has a sagittal crest associated with the expansion of the upper temporal fenestra.

These features are more common among modern birds. Some traits, such as the acrodont or pleurodont tooth implantation and spoon-shaped sclerotic bones are unprecedented for dinosaurs as a whole, and instead, are common among modern lizards. A patch of seemingly scaly skin occurs near the base of the skull, unusual for a bird, but consistent with a lepidosaur identity. The high tooth count and apparent lack of an antorbital fenestra or quadratojugal bone have also been used to argue against an avialan identity.

However, Parrish also noted that Gracilisuchus differed from other rauisuchians in the absence of an ossification at the back of the top of the skull, and the absence of a fenestra between the premaxilla and maxilla. In a 1994 analysis, Lars Juul moved Gracilisuchus inside the Paracrocodylomorpha, placing it as the sister taxon of Postosuchus (then a poposaurid). Paracrocodylomorpha, in turn, was united with the Ornithosuchidae to form the Dromaeosuchia. Both analyses suggested that the squamosal flange of Gracilisuchus was homologous with that of Postosuchus and crocodylomorphs.

Although there are no bony crests or horns, like those found in some other abelisaurids, such as Carnotaurus, rough ridges on the snout and above the eyes might have supported some kind of crest made out of keratin, which would not have become fossilized. The skull roof is thickened. There are also very large fenestrae (window-like openings) in the skull, which are found in many dinosaurs and reduce skull weight. One of these is a large triangular antorbital fenestra in the side of the snout.

This structure is formed by the dorsally arching nasals, and has been described as a 'roman-nose' following Romer's initial description. A similar structure is found in other loricatans, particularly Prestosuchus and Batrachotomus, although it is most prevalent in Luperosuchus. The orbit is tall and has smooth boundaries, without the "keyhole" shape of many other loricatans. The upper part of the infratemporal fenestra was also tall and narrow, although it may have been much wider near the lower rear corner of the skull, which was not preserved.

Biseridens is known mostly from skull and jaw material, as well as a series of 14 vertebrae associated with one skull. Like other anomodonts, the region of the skull in front of the eyes is relatively short compared to other therapsids. The orbits are large and rounded, and the temporal fenestra are large and wide and broad zygomatic arches, similar to but not as developed as those of later dicynodonts. The skull is estimated to be at least long, relatively small compared to other basal anomodonts.

The known remains of Macrocollum are relatively well preserved. The holotype specimen consists of an almost complete and articulated skeleton. The two paratype specimens are both articulated skeletons with one missing a skull and its cervical series. Macrocollum itaquii differs from all other known sauropodomorphs based on a unique combination of characters such as those found on the skull, which include an antorbital fossa perforated by a promaxillary fenestra, and a medial margin of the supratemporal fossa with a simple smooth curve at the frontal/parietal suture.

In the skull the eye socket forms the largest opening, larger than the fenestra antorbitalis that is clearly separated from the slit-like bony naris. No bony crest is visible on the rather straight top of the skull or snout. The lower jaws are thin at the back but deeper toward the front where they fuse into the symphysis ending in a toothless point after which the genus has been named. In MBR 1920.16, the mandibula as a whole has a length of 147 millimetres.

Lastly, the braincase of Panderichthys demonstrates a key intermediate within the fish-evolution sequence. From the outside, Panderichthys has a tetrapod-like head, but actually retains an intracranial joint that is a characteristic of fish. Panderichthys shares many features with the osteolepiform Eusthenopteron such as similar hyomandibular and basipterygoid processes. Even though its head is shaped similar to that of a tetrapod, tetrapod craniums lack a lateral commissure, jugular groove, basicranial fenestra, arcual plate, and intracranial joint, all of which are present in Panderichthys.

The snout of Eotriceratops was relatively flat and elongated. The depressions on the sides of the praemaxillae were connected through an oval fenestra interpraemaxillaris; small rounded processes pointed to above and behind into this opening, originating from the front lower edges. The strut between this opening and the nostril was narrow in side view and transversely thickened with a straight rear edge. The processes jutting into the nostrils had hollow outer sides but were far less excavated and much higher than with Triceratops or Torosaurus.

The characteristic skull of pachycephalosaurs is a result of the fusion and thickening of the frontals and parietals, accompanied by the closing of the supratemporal fenestra. In some species this takes the form of a raised dome; in others, the skull is flat or wedge-shaped. While the flat-headed pachycephalosaurs are traditionally regarded as distinct species or even families, they may represent juveniles of dome-headed adults.[2][3] All display highly ornamented jugals, squamosals, and postorbitals in the form of blunt horns and nodes.

The dentary bone of the lower jaw has ten teeth on either side, with two diastemata separating them. The forward-most teeth are suited for capturing food, while the back teeth are adapted for food processing. The palatine bone in the roof of the mouth connects to the maxilla bone of the snout by a region of bone called the cuneiform process. Caipirasuchus also has large pterygoid and ectopterygoid bones and a well-developed hole in front of the eye sockets called the antorbital fenestra.

This ventral process connects to the quadratojugal bone, which itself contacts the rear branch of the jugal and forms the rear lower corner of the temporal fenestra. The quadrate bone, which forms the cranium's contribution to the jaw joint, is located inwards from the squamosal's ventral process. The quadrate not only contacts the lower jaw, but also connects to the inner face of the quadratojugal and is overlapped by the 'hood' of the squamosal. The appearance of the quadrate is yet another unique aspect of Vancleavea.

The skull of Platyognathus is small, being about in length. The snout is narrow and shorter than the remainder of the skull, as indicated by the anterior position of the antorbital fenestra. Two teeth, dentaries 5 and 6, are enlarged into caniniforms in the lower jaw. Paired caniniform teeth are not seen in any other described crocodyliform taxa, but they have been recorded from an unidentified crocodyliform from the Lower Jurassic Kayenta Formation and from a protosuchid from the Lower Jurassic McCoy Brook Formation in Nova Scotia.

Acleistorhinus (ah-kles-toe-RYE-nuss) is an extinct genus of parareptile known from the Early Permian (middle Kungurian stage) of Oklahoma It is notable for being the earliest known anapsid reptile yet discovered. The morphology of the lower temporal fenestra of the skull of Acleistorhinus bears a superficial resemblance to that seen in early synapsids, a result of convergent evolution. Only a single species, A. pteroticus, is known, and it is classified in the Family Acleistorhinidae, along with Colobomycter (also from the Early Permian of Oklahoma).

At the back of the antorbital fenestra is the jugal, which has often been illustrated as a small V-shaped, two-pronged structure, but it is actually large and has four prongs. The lacrimal process extends forward and upward from the main body of the jugal, while the more robust postorbital process extends backward and upward. Collectively, they enclose the bottom of the eye socket, with angles of 45° on each side. The pear-shaped eye socket measures tall and wide at the widest point.

Kileskus has been included in two phylogenetic analyses and found to be a basal proceratosaurid both times. Although it is unknown whether Kileskus sported a nasal crest, it can be assigned to Proceratosauridae due to a number of other features. These include elongated external nares, a short ventral margin of the premaxilla, and the area of the antorbital fossa directly below the antorbital fenestra being deeper than the maxilla directly below it. Kileskus also shares with Proceratosaurus nares inclined posterodorsally at a 40 degree angle to the skull.

Ascendonanus was about 40 cm long, although the end of the tail is missing in all specimens and the full body length in life is not currently known. It is the smallest known member of the clade Varanopidae, a group of early synapsids that generally resembled the unrelated monitor lizards. Features that identify Ascendonanus as a "pelycosaur" grade synapsid and a member of the Varanopidae include a single lateral temporal opening (fenestra) in the skull, a ridge on the underside of the centra of the vertebrae, and enlarged blades on the ilium of the pelvis.

Reconstructed skull in Japan, based on large size estimates Though incompletely known, the skull of Giganotosaurus appears to have been low. The maxilla of the upper jaw had a long tooth row, was deep from top to bottom, and its upper and lower edges were almost parallel. The maxilla had a pronounced process (projection) under the nostril, and a small, ellipse-shaped fenestra (opening), as in Allosaurus and Tyrannosaurus. The nasal bone was very rugose (rough and wrinkled), and these rugosities continued backwards, covering the entire upper surface of this bone.

The orbits (eye sockets) were large and faced sideways, as in other ornithomimids. The temporal region at the side of the skull behind the eyes was deep, and the infratemporal fenestra (the lower opening behind the orbit) was nearly triangular and smaller than that of the related Struthiomimus. It had deep muscle scars at the back part of the skull roof, along the parietal bone. The parasphenoid (a bone of the braincase, at the underside of the skull's base) was thin-walled, hollow and formed a pear-shaped, bulbous structure.

At the Lode Quarry, Latvia, two specimens of Asterolepis ornata were found to have a fossa deep in the orbital fenestra that is treated to be the hypophysial foramen. The Asterolepis is blind and eyes and nostrils are directed antero-latero-dorsally. Water would reach the nasal sacs directly through the nostrils and exit the sacs laterally along the anterior process of the sclerotic ring. The tail is covered ganoid scales like the armour which are modified cosmoid scales consisting of a bony basal layer, a layer of dentine, and an outer layer of ganoine.

The antorbital fenestra is very small and has no fossa surrounding it. Much of the bone that forms the snout has small pits and grooves running along it. The premaxilla has a large dorsal portion which frames the external nares and fits between the maxilla and the nasal bone, which has led to the suggestion that there may have been fleshy soft tissues around this area in life. Each premaxilla has two dental alveoli, although only one of the four teeth remains in the skull, and a rough, rugose surface where there are no alveoli.

The nasal bones at the top of the snout are also longer (from front-to-back) and thinner (from side-to-side) than those of Marmoretta. As with most early lepidosauromorphs, the posterior process (rear branch) of the jugal was very short, leaving the lower temporal fenestra open from below. Preserved postemporal bones, such as the postorbital and squamosal, were smaller and more conservative in shape than those of other early lepidosauromorphs. The rear of the parasphenoid had a small patch of teeth, a plesiomorphic feature not present in most saurians.

The genus is characterized by a short, high body, a fenestra-less premaxilla, and by the long and narrow postcleithrum reaching the ventral margin of the belly. Other characteristics are the axial skeleton with thirty vertebrae, of which only seven are abdominal; dorsal and anal fins with long bases; a ventral, well- developed pectoral fin; a naked body, devoid of scales except for two dorsal postoccipital and three lateral scutes at the base of the tail; and with a reduction and fusion of the endoskeletal elements of the caudal fin.

Features in Culebrasuchus that are not found in other caimanines include the lack of ridges above the eye sockets and the large size of a hole in the lower jaw called the external mandibular fenestra. These features may be plesiomorphic ("primitive") for alligatorids. Culebrasuchus also has a straighter lower jaw than most other alligatorids, it lacks the ridges on the frontal bone between the eye sockets that are common among crocodylians, and the fourth tooth of the maxilla (rather than third, as in almost all other alligatorids) is the largest in the upper jaw.

Cardiocorax was first named by Ricardo Araújo, Michael J. Polcyn, Anne S. Schulp, Octávio Mateus, Louis L. Jacobs, A. Olímpio Gonçalves and M.-L. Morais in 2015 and the type species is Cardiocorax mukulu. The generic name is derived from Latinised Greek Kardia, meaning "heart", plus corax, meaning "raven/crow" which is also the source of the name "coracoid", in reference to the heart-shaped fenestra between the coracoids which is unique to this genus. The specific name comes from the word mukulu in Angolan Bantu dialects, which means "ancestor".

The specific name refers to Chaoyang. The genus is based on holotype HGM 41HIII-305A (Henan Geological Museum at Zhengzhou), the articulated skull and skeleton of a single individual, with a wingspan of 1.4 meters (4.6 ft). Shenzhoupterus lacked teeth, and had a crest on its skull that arched over the eyes and terminated in a small point toward the back of the head. The nasoantorbital fenestra (an opening incorporating the holes for the nostrils and the antorbital fenestrae) was large and extended over the eyes and braincase.

The skull of Turfanosuchus was proportionally similar to that of other small generalized archosauriforms such as Euparkeria and Gracilisuchus. The premaxilla (a toothed bone at the tip of the snout) projects a small prong behind the nares (nostril holes). This prong, known as a posterodorsal process, bisects a corresponding branch of the nasal bones (which formed the upper surface of the snout). As with other archosaurs and their relatives, the side of the snout has a hole (known as an antorbital fenestra) surrounded by a lowered basin of bone (known as an antorbital fossa).

The external naris was large and located in a hindwards position, similar to tetanuran theropods. The orbit was large, while the lateral temporal fenestra was not as large as would be expected from more derived (or "advanced") members of the Ceratosauria. Uniquely to Limusaurus, the inner bottom edge of the premaxilla, the frontmost bone of the upper jaw, was convex. The nasal bone was distinct in having a "shelf" on its side, was short, wide, less than one third of the length of the , and twice as long as it was wide.

Oedaleops has a wide and low skull with a convex margin when viewed from the side. It has large orbits or eye sockets and numerous teeth, the most of any caseasaur. It differs from its closest relative Eothyris in having a frontal bone that forms a greater portion of the upper margin of the orbit. Another distinguishing feature of Oedaleops is the thinness of the postorbital bar, a strut of bone separating the back of the orbit from a hole in the back of the skull called the temporal fenestra.

It has a long and tapering posterior process (rear branch) and a shorter ascending process (upper branch) separated by a triangular antorbital fenestra which forms a 40 degrees angle. The maxilla also has an unusually long anterior process (forward branch), forming the "stem" of the Y shape. It is uncertain whether the front edge of the maxilla formed part of the naris (like Batrachotomus) or contacted the premaxilla (like other loricatans). The possible quadratojugal fossil is thick and sharply angled, apparently contacting a long jugal but not the quadrate, unlike its relatives.

Shared tetanuran features include the maxillary fenestra (an opening in the antorbital fossa), a pneumatic excavation in the jugal, and the position of the maxillary teeth anterior to the orbit. The posterior skull is little modified in tetanurans, except within Spinosauridae. In the postcranial skeleton, tetanurans transition between the most primitive theropod morphologies in basal tetanurans towards more derived, bird-like states in coelurosaurs. Most tetanurans possess specialized wrist bones, the absence or reduction of the fourth digit of the hand, a strap-like scapula, stiffened tails, and a laminar astragalar ascending process.

Pricesaurus is thus exclusively known from cranial material. Both specimens were probably found in the Romualdo Member of the Araripe Basin and both are part of the collection of the Centro de Pesquisas Paleontológicas da Chapada do Araripe. Martins-Neto provided a diagnosis of four distinctive traits: the breadth of the premaxillae; the closely positioned teeth; the deep premaxillary tooth sockets; and the rounded front of the fenestra nasoantorbitalis. However, in 1988 Alexander Kellner concluded that Pricesaurus was a nomen vanum, primarily because the specimens almost certainly represented different individuals.

Its skull had large nasoantorbital fenestrae (opening that combined the antorbital fenestra in front of the eye with the bony nostril), and part of its palate was concave. The lower jaw was blade-like, and may have turned slightly upwards. The closest relative of Thalassodromeus was Tupuxuara; both are grouped in a clade that has been placed within either Tapejaridae (as the subfamily Thalassodrominae) or within Neoazhdarchia (as the family Thalassodromidae). Several theories have been suggested to explain the function of Thalassodromeus's crest, including thermoregulation and display, but it likely had more than one function.

The dentary projects somewhat posteriorly, forming the edge of the external mandibular fenestra. Both angular and surangular extend to the top of the coronid process, and the surangular forms much of the jaw articulation. The articular has a glenoid for the quadrate condyles; it is saddle-shaped, with no anterior or posterior lip, although there is a prominent attachment crest posteroventral to the jaw joint. The teeth have subconical crowns that curve in towards the centre of the mouth; all are fairly small and not very worn, indicating relatively little use.

'" The second, in contrast, should not only be difficult for speakers of European languages, but Malay speakers likely will not understand the Chinese words, Chinese speakers will likely not understand the Japanese words, and Japanese speakers likely will not understand the Malay words: :Mata-hari yu: "Wo-ti nama mata-hari. Wo taihen brillante. Wo leva wo a est, dan toki wo leva wo, ada hari. Wo miru per ni-ti fenestra sama wo-ti mata brillante como kin, dan wo yu ni toki ada tempo a levar ni.

Aerosaurus (meaning "copper lizard") is an extinct genus within Varanopidae, a family of non-mammalian synapsids. It lived between 252-299 million years ago during the Early Permian in North America. The name comes from Latin aes (aeris) (combining stem: aer-) “copper” and Greek sauros “lizard,” for El Cobre Canyon (from Spanish cobre “copper”) in northern New Mexico, where the type fossil was found and the site of former copper mines. Aerosaurus was a small to medium-bodied carnivorous synapsid characterized by its recurved teeth, triangular lateral temporal fenestra, and extended teeth row.

The postorbital is composed of the anteroventral, posterodorsal, and dorsomedial processes in equal length. The anteroventral process does not come into contact with the ectopterygoid but it does indeed reach farther down the medial side of the jugal. The posterodorsal process forms a great portion of the smooth cranial rim of the upper temporal fenestra and contacts the parietal below the postfrontal. Information of the lower jaw had to be put together from the pieces of the different SAM fossils as there is not one that had a complete lower jaw.

The skull material known is fragmentary, with a few parts of the cranium, the maxilla and some of the rostrum, and several examples of teeth. The maxilla is long, as is the preorbital fenestra just above it, and has a break indicating that there was probably a large medial process. The whole snout was slightly elongated but quite narrow. The blade-like teeth are laterally compressed and serrated, with a slight backwards curve, and would have been excellent for slicing through flesh, clearly indicating that Scythosuchus was a carnivore like other rauisuchids.

Life restoration of Paleorhinus cf. arenaceus Dzik & Sulej (2007) assigned several skulls, partial articulated postcranial skeletons, and numerous isolated phytosaur bones in various ontogenetic stages from Krasiejów, Poland to Paleorhinus cf. arenaceus. They found some similarities between the material and P. bransoni and also Ebrachosuchus neukami or F. angustifrons (mistakenly referred to as E. broili), as well as some apparent differences with Parasuchus. The shape of the external mandibular fenestra of the material resembled that of "Zanclodon" arenaceus but it is also shared with the proterochampsid Chanaresuchus bonapartei.

This is connected indirectly with the eardrum via a mostly cartilaginous extracolumella and medially to the inner-ear spaces via a widened footplate in the fenestra ovalis. The columella is an evolutionary derivative of the bone known as the hyomandibula in fish ancestors, a bone that supported the skull and braincase. The structure of the middle ear in living amphibians varies considerably and is often degenerate. In most frogs and toads, it is similar to that of reptiles, but in other amphibians, the middle ear cavity is often absent.

Like some other ophthalmosaurids, Sveltonectes has a projection on the nasal bone of the skull into the naris, a prefrontal forming part of the margin of the naris and a frontal forming part of the margin of the supratemporal fenestra. Sveltonectes is unique in that it has small, sharp teeth and numerous other peculiar features such as a very primitive prootic. The distinctive shape of these teeth suggest that it had a different feeding habit than other cretaceous ophthalmosaurids. Within the Ophthalmosauridae, Sveltonectes is most closely related to Aegirosaurus.

Skull in left lateral and occipital view The holotype of Sahitisuchus is well preserved, although during preservation the skull became slightly compressed dorsoventrally. This effect is mainly observable on some elements of the rear portion of the skull, particularly the supraoccipital that is displaced towards the foramen magnum. The tip of the snout and the premaxillae are broken off. Sahitisuchus possesses the two following autapomorphies among sebecids: the odontoid process is fused to the axis with vertical anterior surface, lacking medial processes, and its mandible lacks an external mandibular fenestra.

The mandibular symphysis (where the two-halves of the lower jaw connected) was short, deep, and very pneumatised (with air-spaces). The mandibular fenestra was large and was located at the front part of the lower jaw. As in most other oviraptorids, the front of the lower jaw was down- turned. Though Nemegtomaia does not possess any single feature that distinguishes it from other oviraptorids (autapomorphies), the combination of a crest, an enlarged first finger, and a high number of sacral vertebrae (eight), is unique to this taxon.

They are now more correctly referred to as stem mammals or proto-mammals. Synapsids evolved from basal amniotes and are one of the two major groups of amniotes, the other being the sauropsids, the group that includes reptiles and birds. The distinctive temporal fenestra developed in the ancestral synapsid about 312 million years ago, during the Late Carboniferous period. Synapsids were the largest terrestrial vertebrates in the Permian period, 299 to 251 million years ago, although some of the larger pareiasaurs at the end of the Permian matched them in size.

Sereno stressed that the general build was gracile and that the forelimbs and the lower leg were relatively long: the humerus has length of forty centimetres and the tibia and fourth metatarsal measure 687 and 321 millimetres respectively, as compared to a thighbone length of seventy-six centimetres. Several autapomorphies have been established, traits that distinguish Afrovenator from its nearest relatives. The depression in which the antorbital fenestra is located, has a front end in the form of a lobe. The third neck vertebra has a low rectangular spine.

Skull Many of the modifications of the bones within the skull seem to reduce drag and help propel the animal through an aqueous environment while swimming and feeding. The skull of Stereosternum is equal to the length of the neck and the anterior half of the skull is not as elongated as in Mesosaurus and this is due to the extension of the premaxilla, which dominates the snout. The position of the external naris is about half way along the skull. The presence of the lower temporal fenestra is absent in these species.

Sinosaurus has been considered a nomen dubium in a few works, although now that "Dilophosaurus" sinensis is referred to it, it is considered valid. Dilophosaurus sinensis was shown to be a junior synonym of Sinosaurus in 2003. It is possibly closer to the Antarctic theropod Cryolophosaurus, based on the fact that the anterior end of the jugal does not participate in the internal antorbital fenestra and that the maxillary tooth row is completely in front of the eye socket. D. sinensis was exhibited in 1998 at Dinofest in Philadelphia.

In contrast, closure of the opening on the side of the skull behind the orbit, the lateral temporal fenestra, is an advanced, derived (apomorphic) character only known in ankylosaurid ankylosaurians. Two skulls are known, and the skull length for Cedarpelta is estimated to have been roughly . One of the Cedarpelta skulls was found disarticulated, a first for an ankylosaur skull, allowing paleontologists a unique opportunity to examine the individual bones instead of being limited to an ossified unit. The skull is relatively elongated and does not show a strongly appending beak.

Their phylogenetic analysis, based on the matrix of Norman (2015), found Choyrodon to be the sister taxon of Eolambia. Eolambias commonly recovered relative Protohadros was not present in this matrix. Three characteristics supported this sister relationship: a trapezoidally-shaped occiput, and two shared traits of the teeth. The placement of these genera relative to other hadrosauriformes depended on whether the antorbital fenestra was coded as present or absent in Choyrodon; the juvenile type specimen has one, but the possibility that adults would have a closed one couldn't be ruled out.

Petrarch's sonnets were dedicated solely to Laura. She is thought to be an imaginary figure and a play on the name Laurel, the leaves with which Petrarch was honored for being the poet laureate and the very same honor he longed for in his sonnets as a “Laurel Wreath”. The name game has a further layer: "L'aura" is also "gold", the colour of her hair. In the allegorical canzone 323 (Standomi un giorno solo a la fenestra), we see that the mysterious phoenix has a head of gold.

The first phytosaur taxon discovered in North America was believed to be from a skull of Belodon buceros in 1881 in the Chama basin, of north-central New Mexico. The species has also been attributed to other genera, including Pseudopalatus, Phytosaurus, Machaeroprosopus, Arribasuchus and Nicrosaurus. Some attributed the skull type to Nicrosaurus because of a few cranial characteristics, pertaining to the squamosal and supra-temporal fenestra. In comparison to Nicrosaurus kapffi, it carried a more narrow snout and therefore was referred to as Nicrosaurus buceros by some scientists.

The antorbital fenestra is present as a bean-shaped depression, its lower edge formed by a sharp ridge. The central parietal crest on the skull roof is formed by two parallel crests separated by a narrow trough on the midline. The roof of the nasal cavity is formed by special plates above the vomers, called the "epivomers". The epipterygoid bone is shaped as a small conical vertical structure of which the base connects to the upper side of the pterygoid bone by means of a lateral flat surface.

The breastbone bore a strong keel for the attachment of flight muscles, and contained a distinct opening or fenestra, a unique characteristic of yanornithiformes. The upper and lower arm were about the same length. Like other ornithurines, Yixianornis had a highly fused hand, with many wrist bones joined together that are free in more primitive birds. The hips and hind limbs preserved more primitive features than the forelimbs, supporting the idea that the modern adaptations in the locomotion seen in modern birds evolved after the many specializations needed for flight.

The light rays might sometimes include an inscription,Blum (1992), 46 and were sometimes shown entering her ear, in the belief that it was thus the Word became flesh. Memling did not depict the light as distinct rays, nor had Dieric Bouts's Getty Annunciation. Yet the room is bright, filled with sunlight, a fenestra incarnationis, which would have been an adequate symbol for the contemporary viewer.Blum (1992), 47 By the mid-15th century the Virgin is found depicted in a room or chamber near an open window to permit the passage of light.

These latter taxa also have a longer snout, with more distance from the first tooth until the nasal process of the premaxilla. As well, Europasaurus shares with the basal camarasauromorphs (brachiosaurids, Camarasaurus, Euhelopus and Malawisaurus) a similarly sized orbit and nasal fenestra, whereas the nasal opening is significantly reduced in derived titanosaurs (Rapetosaurus, Tapuiasaurus and Nemegtosaurus). Teeth of the upper jaw A single maxilla is present in the well-preserved material of Europasaurus, DFMMh/FV 291.17. This maxilla has a long body, with two elongate processes, a nasal and a posterior process.

Skulls of two dicraeosaurids in dorsal view, showing the placement of the parietal fenestra and the postparietal foramen Among the nasal bones of Europasaurus, several are known, but few are complete or undistorted. The nasals are overlapped posteriorly by the frontal bones, and towards the side, they articulate bluntly with the prefrontals. Unlike the nasals of Giraffatitan, those in Europasaurus project horizontally forwards, forming a small portion of the skull roof over the antorbital fenestrae. Four frontals are known from Europasaurus, three being from the left and one being from the right.

209; Voss and Weksler, 2009, pp. 75, 77 Oryzomys gorgasi is distinguished from other Oryzomys species by its short rostrum, the form of its incisive foramina, the absence of sphenopalatine vacuities, and the near absence of a subsquamosal fenestra. Within the species, the Colombian specimen differs from the Venezuelan animals in being larger in some measurements, but having smaller teeth, and in having oddly shaped wear facets of the incisors. The Colombian animal was probably kept in captivity for some time after it was caught, which would explain its large size and odd wear facets.

The only known Vancleavea specimen preserving a complete skull is GR 138, and as a result that specimen is the basis for knowledge of the skull in this taxon. The postorbital region of the skull (behind the eyes) is long and boxy, with a wide and flat skull roof. The preorbital region (in front of the eyes), on the other hand, is short, triangular, and thin. A distinguishing feature of Vancleavea is the lack of an antorbital fenestra, a hole in front of the eyes which is typical for archosauriforms.

It is different from Guanlong in lacking a medial crest on the premaxilla, nasals and frontal bones. It also lacks high external nostrils, and a short anterior maxillary process. It has a shorter premaxillary body, but with a larger maxillary fenestra, a rodlike jugal, closely spaced fine serrations on the distal tooth carinae of the maxilla and dentary. The cervical vertebral centra are elongated with two pneumatic foramina, the neural spines are short and elongated towards the posterior in the dorsal vertebrae, and the pubic shaft is curved at the end.

Sophineta resembles lepidosaurs in having weak zygosphenes, short vertebrae and single−headed ribs throughout the column, but differs in having a shallower pleurodont tooth implantation and the apparent absence of both a thyroid fenestra and functional caudal autotomy. Sophineta had unspecialised vertebral column but fairly derived skull structure, including the tall facial process of the maxilla, reduced lacrimal and pleurodonty. These traits also resemble those of early lepidosaurs rather than stem−lepidosaurs. A reconstruction of the skull of Sophineta revealed a "modified diapsid skull" with a relatively short preorbital region.

Diagram of the skull of Parapsicephalus purdoni, viewed from the left When viewed from the side, the convex top of the skull formed a gentle slope. The elongate frontal process of the premaxilla, which extends backwards towards the eyes, may have supported a low crest along its midline. Below the nostril, the premaxilla meets with the maxilla; their junction is marked by a discontinuity in the surface texture of the bone. Overall, the oval-shaped antorbital fenestra, situated behind and separate from the nostril, measures long and tall.

The frontal, which is located on the top of the skull between the premaxilla and the eye socket, takes the shape of a sub-rectangle with a large, rhombic process extending forward to meet the nasal. The frontal process of the premaxilla cuts into the frontal along the midline of this rhombus. Contacting the rear ends of both the frontal and jugal is the thin and triangular postorbital, about long along the bottom, extends backwards to separate the infratemporal and supratemporal fenestrae. The supratemporal fenestra itself is a somewhat four-sided oval.

Qianxisaurus is a basal eosauropterygian, potentially related to Nothosauroidea, with an estimated total body length of at least 80 cm. Originally considered to be a juvenile of the nothosaurid Lariosaurus due to the presence of four sacral vertebrae, further preparation revealed its unique skull roof and dentition morphology. Qianxisaurus bears a premaxilla with eight teeth, contributing a small portion to the elongated oval external naris, teeth with a slightly constricted peduncle and a short conical crown, and a very small supratemporal fenestra, only slightly larger than the foramen of the parietal bone. These autapomorphic traits are unique to Qianxisaurus among all known eosauropterygians.

The rear lower corners of the orbits are formed by the jugal bones, which extend to the lower part of the skull's postorbital region (behind the eyes). Each jugal had a long and spur-like rear projection which reached as far back as the squamosal bone in the back of the skull. However, this rear projection stretches above each lower temporal fenestra, a hole in the side of the rear part of the skull. This leaves the hole completely open at the bottom, while in many other reptiles the jugal encloses the hole from the bottom.

The species is diagnosed by a combination of skull features that it shares with basal caimans like Tsoabichi, Eocaiman, Culebrasuchus, and the living genus Paleosuchus, as well as more derived caimans such as those in the genus Caiman. One feature that distinguishes Centenariosuchus from all other caimans is the straight outer margin of a hole on the underside of the skull called the suborbital fenestra. According to one phylogenetic analysis of caimanine relationships, Centenariosuchus falls within a clade or evolutionary grouping of caimans that includes the very large and highly specialized forms Purussaurus and Mourasuchus, known from the Miocene of South America.

The lower temporal fenestra is not fully enclosed in early archosauromorphs (and choristoderes) due to alterations to the structure of the quadratojugal bone at the rear lower corner of the skull. This bone is roughly L-shaped in these taxa, with a tall dorsal process (vertical branch), a short anterior process (forward branch), and a tiny or absent posterior process (rear branch). The bones surrounding the quadratojugal also reconfigure to offset the changes to the quadratojugal. For example, the lower branch of the squamosal bone is shortened to offset the tall dorsal process of quadratojugal which connects to it.

As sound waves vibrate the tympanic membrane (eardrum), it in turn moves the nearest ossicle, the malleus, to which it is attached. The malleus then transmits the vibrations, via the incus, to the stapes, and so ultimately to the membrane of the fenestra ovalis (oval window), the opening to the vestibule of the inner ear. Sound traveling through the air is mostly reflected when it comes into contact with a liquid medium; only about 1/30 of the sound energy moving through the air would be transferred into the liquid.Hill, R.W., Wyse, G.A. & Anderson, M. (2008).

The longest is metatarsal III with a length of ; it is placed more anteriorly than the other metatarsals. Metatarsal I is more posterior and its upper part is transversely reduced to a splint. Some distinguishing traits of Jeholosaurus include: enlarged laterodorsal nasal foramina; a quadratojugal fenestra more than 25% maximum quadratojugal length; a quadratojugal less than 30% of skull height; a predentary with almost 150% of premaxillary body length; a dentary extending posteriorly almost to the posterior border of the angular; and the claw of the third toe being longer than the other third toe phalanges.

The basipterygoid processes are long, slender, and project downwards and outwards like Plateosaurus and unlike Lufengosaurus and Jingshanosaurus, forming an angle of 80° with each other. Compared to Lufengosaurus, Yunnanosaurus, and Jingshanosaurus, the angular and surangular extend much further in front of the mandibular fenestra in Xingxiulong, which is closer to Adeopapposaurus and Plateosaurus. The articular bears an inward- projecting and pyramidal process as an extension of the jaw joint; at its back end, it also possesses an upward-directed and tab-like process, which is also seen in Coloradisaurus, Jingshanosaurus, and an as-of-yet unnamed sauropodomorph.

Worn teeth from the lower jaw have not yet been discovered, but they are expected to show opposing tooth-to-tooth wear. The ability to raise their heads well above the ground does not necessarily mean they browsed on items there, and the short neck of Nigersaurus would have restricted the browsing range compared to other diplodocoids. The adductor muscle of the jaw appears to have attached to the quadrate instead of the supratemporal fenestra. Both this and the other mastication muscles were likely weak, and Nigersaurus is estimated to have had one of the weakest bites of the sauropods.

Although the complete shape and height of this structure is unknown in Irritator, these head crests were commonplace in spinosaurids, having possibly served a display function when the animal was alive. The preserved part of Irritators crest is deepest above the antorbital fenestra and lacks the vertical ridges seen in the crest of Spinosaurus. Like others in its family, Irritator possessed a long and bony structure on the roof of its mouth called a secondary palate, separating the oral from the nasal cavity. This is a feature observed in extant crocodilians, but absent in most theropod dinosaurs.

The skull of Counillonia is short and relatively slender in construction, with the typically broad temporal fenestra of most dicynodonts at the back (although they are relatively reduced for a dicynodont) and a short, narrow snout that comes to a squared-off beak tip. The caniniform process of the maxilla is short and directed anteriorly so that the tusks point somewhat forward as well as down, and sits entirely in front of the eyes. The upper jaw is completely toothless apart from these two tusks. The interorbital region between the eyes is narrow, and so the large orbits are characteristically directed upwards.

Overall, the snout is relatively short and deep compared to the long, low skull of Sebecus. A deep notch is present between the maxilla and premaxilla to house the large lower canine tooth, along with a prominent bulge of bone above each. Based on the shape of the known snout, it's likely that Bergisuchus had separate nostril openings that faced laterally on the surface, as well as laterally facing eyes, unlike modern crocodylians. Also, it shares with Iberosuchus the unusual presence of a small antorbital fenestra, a feature that's invariably absent in both baurusuchids and sebecids.

The back of the skull was more lightly built than in some other larger theropods due to extensive skull openings, yet the jaws were deep to support the proportionally large teeth. The lacrimal bone formed not only the back margin of the antorbital fenestra, a large opening between eye and , but also part of its upper margin, unlike in members of the related Abelisauridae. The quadrate bone, which was connected to the lower jaw at its bottom end to form the jaw joint, was inclined so that the jaw joint was displaced backwards in relation to the occipital condyle.

This also led to a broadening of the base of the lateral temporal fenestra, a large opening behind the eyes. The most distinctive feature was a prominent horn situated on the skull midline behind the bony nostrils, which was formed from fused protuberances of the left and right nasal bones. Only the bony horn core is known from fossils—in the living animal, this core would have supported a keratinous sheath. While the base of the horn core was smooth, its upper two-thirds were wrinkled and lined with groves that would have contained blood vessels when alive.

The posterior wall of the supratemporal fenestra inclines dorsally so that it is visible when the skull is viewed in dorsal aspect. In Dyrosaurus phosphaticus, the wall is vertical and thus not visible in dorsal aspect. In both species of Rhabdognathus, the space between the occipital condyle and the basioccipital tubera (both located in the back of the skull where the vertebrae articulate) is anteroposteriorly longer than in D. phosphaticus. In the skulls of both species of Rhabdognathus, the posterior margin is inclined so that both the occipital condyle and the basioccipital tubera below it are visible in occipital view.

Typical features of thalattosaurs are the elongated premaxilla and the relatively large snout, and a small or absent upper temporal fenestra. The cranial reconstruction of Askeptosaurus is consistent with the features previously listed: Askeptosaurus had a very slender and flattened skull. The snout was significantly elongated, the orbits were comparatively large, and the posterior skull table was deeply emarginated. The premaxilla of Askeptosaurus comprises almost half the length of the skull (maximum length is 26 cm (10.2 inches) among the investigated specimens) and forms more than one-third of the tooth row in the upper jaw.

The weight-reducing opening in front of the eye socket (antorbital fenestra) was quite large, more than a quarter of the length of the skull and two-thirds of its height. The outside surface of the maxilla (upper jaw bone) and the upper surface of the nasal bone on the roof of the snout were not nearly as rough- textured as those of Giganotosaurus or Carcharodontosaurus. Long, low ridges arose from the nasal bones, running along each side of the snout from the nostril back to the eye, where they continued onto the lacrimal bones. This is a characteristic feature of all allosauroids.

One of them is the increased angulation of the zygapophyses in the posterior dorsal vertebrae; Evans noted that this character is also present in the skeletons of lizards belonging to the genus Draco, "and is likely to be functional (and thus potentially convergent)". The other one, the enclosed thyroid fenestra in the pelvis, "may be variable in the British kuehneosaurs and remains unknown in Pamelina", according to Evans. The author also noted that there are many differences between the skull of drepanosaurids and kuehneosaurids, and that the only skull characters shared by members of both families are primitive neodiapsid characters.

The smooth narial fossae are located just behind these, and help to give the snout its broad flattened look. The maxillae are, by quite a long way, the largest and most expansive bones in the skull; each holds nineteen small recurved teeth. They have a narrow alveolar margin at the edge of their broad expanse, giving the head of Anatosuchus a rather rectangular appearance, and broad rami that extend above and below the antorbital opening. The upper of these rami form a long suture with the nasal, and then meet the prefrontal and lacrimal directly above the antorbital fenestra.

There remains some uncertainty about whether the slender-headed morph is an advanced ontogenetic stage, as the largest individuals all exhibit this skull morphology. Schoch & Milner (2014) identified 10 features in the diagnosis of Micropholis: (1) dermal ornament with irregularly spaced pustules; (2) accessory fangs on the vomer; (3) unpaired anterior palatal fenestra (sometimes 'fontanelle'); (4) palatine and ectopterygoid reduces to struts along medial maxillary margin; (5) short basipterygoid ramus of pterygoid; (6) basal plate with prominent posterolateral horns; (7) hyobranchial skeleton well ossified; (8) short tail; (9) elongate skull table (plesiomorphy); and (10) postparietal much longer than tabular (plesiomorphy).

Heavily restored skull of S. ferox in the Field Museum The skull of Sphenacodon is very similar to that of Dimetrodon. It is narrow from side to side and vertically deep, with an indented notch at the front of the maxillary bone in the upper jaw. The upper and lower jaws are equipped with an array of powerful teeth, divided into sharp pointed "incisors" [precaniniforms], large stabbing "canines" [caniniforms], and smaller slicing back teeth [postcaniniforms]. The orbit is set high and far back with a single opening (temporal fenestra) behind and partly below the eye, a characteristic of synapsids.

However, the osteoderms of Parringtonia are comparable to a number of other small archosaurs and cannot diagnose it as an erpetosuchid alone. Since Parringtonia lacks all of the autapomorphies or unique characteristics of Erpetosuchus including an otic notch at the back of the skull and a large antorbital fenestra set in a deep fossa on the snout, its classification as an erpetosuchid was tentative at first. Parringtonia was redescribed in 2012 by Nesbitt & Butler and included in a phylogenetic analysis along with Erpetosuchus. The analysis confirmed that Parringtonia and Erpetosuchus were sister taxa in their own clade, which was designated Erpetosuchidae.

The fossil record of Pelanomodon is principally made up of both complete and partial skulls. It is for this reason that morphology of the skull is used to distinguish Pelanomodon from other genus in the Geikiines family. The absence of tusks is a significant feature that is used to differentiate Pelanomodon from Aulacephalodon, in addition to bosses on the post orbital bar and twisting of the zygoma. Pelanomodon is distinguished from Geikia due to its longer temporal fenestra and snout, lesser developed oesophageal crest and flush pineal foramen. In addition to these distinctions, Pelanomodon’s skull has many other characteristic features.

Diapsids ("two arches") are a group of amniote tetrapods that developed two holes (temporal fenestra) in each side of their skulls about 300 million years ago during the late Carboniferous period. The diapsids are extremely diverse, and include all crocodilians, lizards, snakes, tuatara, turtles, and birds. Although some diapsids have lost either one hole (lizards), or both holes (snakes and turtles), or have a heavily restructured skull (modern birds), they are still classified as diapsids based on their ancestry. At least 7,925 species of diapsid reptiles exist in environments around the world today (nearly 18,000 when birds are included).

The frontal was overlapped by the nasal and (bone in front of the eye socket) at the middle front, and its frontmost part contacted the hind end of the nasal. Seen from the side, the hind part of the frontal was dome-like, which indicates that Xixiasaurus had an enlarged braincase. The rim of the (eye socket) was raised, with weak notches along the margins. The lacrimal bone was T-shaped in side view; its front process was very long and reached the hind margin of the antorbital fenestra, forming most of the latter's upper hind border, as in Byronosaurus.

A modified stapes operation, called a stapedotomy, is thought by many otologic surgeons to be safer and reduce the chances of postoperative complications. In stapedotomy, instead of removing the whole stapes footplate, a tiny hole is made in the footplate - either with a microdrill or with a laser, and a prosthesis is placed to touch this area, oval window. This procedure can be further improved by the use of a tissue graft seal of the fenestra, which is now common practice. Laser stapedotomy is a well-established surgical technique for treating conductive hearing loss due to otosclerosis.

In these cases, the stapes either is also missing or, in the absence of an eardrum, connects to the quadrate bone in the skull, although, it is presumed, it still has some ability to transmit vibrations to the inner ear. In many amphibians, there is also a second auditory ossicle, the operculum (not to be confused with the structure of the same name in fishes). This is a flat, plate-like bone, overlying the fenestra ovalis, and connecting it either to the stapes or, via a special muscle, to the scapula. It is not found in any other vertebrates.

That Saurornithoides mongoliensis might be more derived, higher in the tree, than Sinornithoides and Sinusonasus, is indicated by the lack of a fenestra promaxillaris, a small opening at the front side of the snout, and the possession of large denticles on the rear tooth edges as well as the presence of the high number of six sacral vertebrae. That S. mongoliensis might be more basal, lower in the tree, than Zanabazar and Troodon, is shown by the presence of a recessus tympanicus dorsalis, the upper one of three small openings on the side of the braincase, in the inner ear region.

Fourth mandibular tooth in several views The skull of Sahitisuchus is elongated in dorsal view, showing two slight constrictions at about the level of the fifth and eleventh maxillary alveoli, being comparatively shorter than the skull of Sebecus and Stolokrosuchus, but not as short as Lorosuchus. The snout of Sahitisuchus is not as tall and domed (oreinirostral) as seen in Sebecus, Barinasuchus, Bretesuchus, Zulmasuchus and Langstonia. The skull roof of Sahitisuchus is flat and rectangular, being wider than long. The supratemporal fossa is much larger than the supratemporal fenestra and is about three times smaller than the orbits.

A small muscle scar is present on the rear edge near the glenoid (shoulder socket), similar to one observed in Batrachotomus, albeit less distinct. The humerus is narrow and has prominent and well-developed muscle attachments, while the ulna is shorter and quite robust. The ilium is low and similar to that of Ticinosuchus, with muscle scars for two sacral ribs on its inner surface and no vertical ridge on its outer surface. The pubis is somewhat elongated, with its base forming part of the acetabulum and possessing a small perforation known as an obturator fenestra.

The parietal bones are fused with a pointed anterior end, and a fossa is present on the surangular of the lower jaw, in front of the rear surangular foramen. Two other traits are possible autapomorphies: the gracile build of the three postorbital branches and the elongation of the upper chevrons. Gobivenator has a total body length of approximately 160 cm, which is comparable to Saurornithoides in size. The skull of Gobivenator is very well preserved, and shows an enlarged maxillary fenestra and an anterior process of the lacrimal which is much longer than the supraorbital process, features that are typical among troodontids.

The sclerotic rings inside the eye were formed by eleven ossicles (small bones), similar to the amount in other pigeons. The mandible was slightly curved, and each half had a single fenestra (opening), as in other pigeons. 1848 lithograph of the Oxford specimen's skull in multiple views The dodo had about nineteen presynsacral vertebrae (those of the neck and thorax, including three fused into a notarium), sixteen synsacral vertebrae (those of the lumbar region and sacrum), six free tail (caudal) vertebrae, and a pygostyle. The neck had well-developed areas for muscle and ligament attachment, probably to support the heavy skull and beak.

There was little Latin linguistic heritage left to the Welsh language, only a number of borrowings from the Latin lexicon. With the absence of early written Welsh sources there is no way of knowing when these borrowings were incorporated into Welsh, and may date from a later post-Roman era when the language of literacy was still Latin. Borrowings include a few common words and word forms. For example, Welsh ffenestr is from Latin fenestra, 'window'; llyfr is from liber, 'book'; ysgrif is from scribo, 'scribe'; and the suffix -wys found in Welsh folk names is derived from the Latin suffix -ēnsēs.

Although the surangular bone is not preserved, several other bones of the lower jaw are, including a triangular angular bone, a gently curving prearticular bone, and a damaged yet notably concave articular bone. The angular and prearticular formed the lower edge of a large and rounded in the lower jaw (known as a mandibular fenestra) while the articular bone formed the lower part of the jaw joint. A long and tapering hyoid (tongue bone) has also been preserved. The front teeth of the upper jaw are also procumbent, and the margin of the premaxilla curves slightly upward to direct them outward.

The initial description of Incisivosaurus by Xu et al. showed that the skull, which measures approximately in length, preserves the most complete dentition known for any oviraptorosaurian. Their cladistic analysis indicated that Incisivosaurus lies at the base of the oviraptorosaurian group, making it more primitive than Caudipteryx and the oviraptorids. A subsequent study by Osmolska et al. in 2004 described the distinguishing skeletal features of Incisivosaurus, including a long snout that made up about half the total length of the skull, a slender lower jaw with a long fenestra (opening), and its distinctive, large, flattened front teeth.

Perhaps they are pointing outwards to a degree but the deformation of the fossil by compression makes this uncertain. On top of the skull, behind the snout proper, above the fenestra a longitudinal low bony crest is present. It consists of fibrous bone, vertically directed, which might have formed the base for a much higher crest of soft tissue. The crest starts above the twelfth tooth position; its limit at the back is unknown because of damage but it is considered unlikely that it extended as far as the eyes, the roof of the skull not showing any trace of it.

The brow horns span approximately 40% of the total length of the skull, almost reaching the level of the snout tip, and with a bone core length of up to 457 millimetres are the longest known of any centrosaurine, both in absolute and relative terms. Skull diagram The epijugal (cheek horn) has a length of , also the largest known among centrosaurines. The skull frill is moderately long, and pierced by a large kidney-shaped parietal fenestra at each side. Apart from the midline epiparietal, there are seven epiparietals at each side, and about four to five episquamosals.

Most of the other mandibular teeth could not be assessed due to the overlapping snout obscuring details, but seem to resemble the maxillary teeth. The surangular and articular bones (which form the rear upper part of the mandible) were smooth and thin. These features are unique to Venaticosuchus compared to other ornithosuchids, which have a noticeable pit on both the outer surface of the surangular and the inner surface of the articular. The angular bone (which forms the rear lower part of the mandible) was elongated, forming the entire lower edge of the mandibular fenestra and being covered with striations.

Uniquely among troodontids, the postorbital bone is slender and radiates into three processes. Like Zanabazar, there is a pneumatic diverticulum in the jugal bone where an air sac was present within the bone; there is also a pneumatic opening on the rear side of the quadrate bone, as in other troodontids. Unlike Sauronithoides, Zanabazar, and Stenonychosaurus, the crest separating the parietal bones does not participate in the border of the supratemporal (upper) temporal fenestra at the back of the skull. Characteristic of troodontids, Liaoningvenator has a pitted groove on the outer edge of its shallow and triangular lower jaw.

Among ctenochasmatids, the jugal bone of Liaodactylus is quite narrow, especially below the large eye socket. It splits into three branches: the very long and tapering anterior process, which forms the back two-thirds of the bottom border of the nasoantorbital fenestra; the vertical orbital process; and the angled temporal process, which is very long compared to the orbital process. The bone is bent slightly such that the margin of the jaw below the eye socket is curved. At the back, the temporal process of the jugal has fused rather extensively with the neighboring quadratojugal bone.

Zhou et al. assigned Liaodactylus to the Ctenochasmatidae in 2017 based on a phylogenetic analysis. It shares with other ctenochasmatids the relative proportions of its skull height at the squamosal bone, its skull height at the jaw joint, and the length of the snout at the level of the nasoantorbital fenestra; additionally, in terms of morphological characters, it shares a retroarticular process that is pointed backwards and downwards. Within the Ctenochasmatidae, Liaodactylus was found to be closest to Ctenochasma, with which it shares the ratio of jaw-to-skull length and the teeth being angled out to the sides.

Zatracheidae (sometimes mistakenly spelled Zatrachydidae or Zatrachysdidae) is a family of Late Carboniferous and Early Permian temnospondyl amphibians known from North America and Europe. Zatracheidids are distinguished by lateral (sideways) bony protuberances of the quadratojugal bone of the skull, and a large opening in the snout called the internarial fontanelle (sometimes the internarial fenestra) that is bordered by enlarged premaxillae. The skull is flattened, with small orbits or eye sockets set far back. The opening in the snout may have housed a gland for producing a sticky substance so that prey would adhere to the tongue.

Another stem tetrapod, Sigournea multidentata from the Early Carboniferous of the United States, may also be related to Spathicephalus. Named in 2006 from a Visean-aged fissure fill deposit in Iowa, Sigournea is slightly older than Spathicephalus. It resembles both Spathicephalus and Doragnathus in having numerous small, closely packed teeth. Sigournea differs from Spathicephalus and resembles Doragnathus in having pointed rather than chizel-shaped marginal teeth and a second row of teeth in the lower jaws, and differs from both taxa in having a hole on the inner surface of the lower jaw called the exomeckelian fenestra.

Australothyris is known from a single specimen discovered at the Beukesplaas farm by Robert Smith in 1995. The fossil site at the Beukesplaas farm contains a diverse parareptile and synapsid fauna positioned in the Middle Permian Tapinocephalus Assemblage zone of the upper Abrahamskraal Formation. This specimen, SAM-PK-K8302, included most of a skull and portions of the rest of the skeleton, which had mostly been eroded away prior to its discovery. It was initially referred to Owenetta based on the numerous teeth and long postfrontal, until a reexamination revealed a temporal fenestra, which was absent in owenettids.

Although the frontal does contact the upper edge of the orbit as in other amniotes, it lacks the distinct lappet observed in lanthanosuchoids. A distinct lateral temporal fenestra is present behind the orbit, completely surrounded by the jugal, quadratojugal, postorbital and squamosal. Other parareptiles with lateral temporal fenestrae (apart from lanthanosuchids) typically exclude the postorbital from its edge through contact between the jugal and squamosal, or have an open lower edge due to a loss of contact between the jugal and quadratojugal. The postfrontal is uniquely elongated, as its rear branch contacts the boxy supratemporal bone and separates the postorbital from the parietal.

The original describers of Australothyris used a phylogenetic analysis designed by Muller & Tsuji (2007) to investigate its relations to other parareptiles. The analysis found that it had an optimal position as a relatively basal parareptile, specifically the sister taxon to Ankyramorpha (the group containing lanthanosuchoids and more derived parareptiles). This was nevertheless more derived than mesosaurs and millerettids, and the paper's authors assigned the name Procolophonomorpha to parareptiles more derived than millerettids. Australothyris was recovered as the first branch of Procolophonomorpha, suggesting that the group as a whole originated simultaneously with the evolution of a large, fully enclosed temporal fenestra in parareptiles.

Protome was named on the basis of several unique characteristics, or autapomorphies. The first autapomorphy is the flat shape of the basitubera, an area at the base of the skull in front of its attachment point with the neck. Another is that bony projections called exoccipital prongs at the back of the skull make up the top margin of the foramen magnum, the hole through which the spinal cord enters the skull. A third autapomorphy is a small depression or fossa surrounding the front tip of a hole in the lower jaw called the mandibular fenestra.

Skeletal reconstruction, by Jaime Headden Goyocephale is a primitive pachycephalosaurian, and was originally included in the family Homalocephalidae, which united the genus with Homalocephale, which also has a flat skull roof. Goyocephale is distinguished from Homalocephale by its overall proportions, the shape of its supratemporal fenestra, and heterodont dentition, although the two share multiple features. However, many more recent phylogenetic analyses tend to find Homalocephalidae to be a paraphyletic family, with the genera included simply being consecutive branches sister to Pachycephalosauridae, or as consecutive branches primitive to Prenocephale but within Pachycephalosauridae. A cladogram illustrating the latter hypothesis is shown below.

In his description of the braincase, he noted its intermediate morphology between that of lizards and birds, which he considered evidence of a close relationship between birds, pterosaurs, and "reptiles". F. Plieninger subsequently compared GSM 3166 to Campylognathoides, and expressed that it was not as close to Scaphognathus as Newton had presumed. Later, in 1919, Gustav von Arthaber, based on the shape of the top of the skull, the elongated nostrils and prefrontal bones, the large antorbital fenestra and eye socket, the deep jugal, and the presence of seven teeth in the maxilla, referred GSM 3166 to the new genus Parapsicephalus.

The head and forelimbs found with Ixalerpeton are the first of these elements that have been found among lagerpetids. Unlike dinosauriforms, the posttemporal fenestra at the back of the skull is large and unreduced; there is an extra bone, the postfrontal, bordering the eye socket; there is no supratemporal fossa, which is an indentation found on the frontal bone in dinosauriforms; and the glenoid cavity on the scapula, where the scapula-humerus joint is located, faces slightly sideways instead of backwards. On the other hand, there is an anterior tympanic recess on the braincase, and the deltopectoral crest on the humerus is long, both of which are common among basal dinosauromorphs.

In 2012 another "stem aetosaur" was described from the Middle Triassic Manda Beds of Tanzania. It differs from other Middle Triassic pseudosuchians in having a long skull, a small antorbital fenestra that fits into a large antorbital fossa in front of the eye socket, sharp and curved teeth, and osteoderms covering much of its body. Like aetosaurs and Revueltosaurus, it has a maxilla that fits into the jugal. Revueltosaurus, Turfanosuchus, and the unnamed Tanzanian pseudosuchian are all good fits for the hypothesized ancestor of aetosaurs because they both have double rows of leaf-shaped osteoderms along their backs that could potentially have evolved into the tightly fitting paramedian osteoderms of aetosaurs.

Dyoplax, a controversial pseudosuchian from Germany, has been proposed to be a close relative of Erpetosuchus. Some similarities between the two taxa include the structure of their osteoderms (including unusual small cervical osteoderms), a recessed antorbital fenestra, ridges completely surrounding the antorbital fossa, large and upward-pointing orbits, and slender limbs. However, the preservation of the only known specimen of Dyoplax, a sandstone mold, makes analysis difficult, and Dyoplax lacks many of the features that characterize other erpetosuchids. Nevertheless, the relation of Dyoplax shares more similarities with Erpetosuchidae than with other groups it has been proposed to be related to, such as Aetosauria and "Sphenosuchia".

In both species, the back of the angular contributes to the retroarticular process. The inner surface of the angular is roughened in K. guimarotae, and the top margin of the inner wall transitions from an upward-projecting tip at the front to a low, rounded crest at the back; the same margin maintains its height along the angular in K. langenbergensis. The surangular bears a thin, forward-projecting process that, in K. langenbergensis, extends forward to the back of the tooth row and bears a groove on the bottom. The presence of the oval-shaped external mandibular fenestra is unique to the genus among atoposaurids.

The classification of Pectodens is complicated by the presence of both characteristics similar to the Protorosauria as well as characteristics which would be expected in more basal archosauromorphs. Like Tanystropheus, Macrocnemus, and other protorosaurs, the cervicals are long with low neural spines, and bear cervical ribs that bridge multiple joints. These same characteristics previously allowed Li, Fraser, and Rieppel to assign Dinocephalosaurus to the Protorosauria. Yet, in Pectodens, the puboischiadic plate (formed from the pubis and ischium) does not appear to bear a perforation known as the thyroid fenestra, the astragalus and calcaneum of the ankle are simple and rounded, and the fifth metatarsal is not hooked.

In therapsids, the hip bone came to rotate counter-clockwise, relative to its position in reptiles, so that the ilium moved forward, and the pubis and ischium moved to the rear. The same pattern is seen in all modern mammals, and the thyroid fenestra and obturator foramen have merged to form a single space. The ilium is typically narrow and triangular in mammals, but is much larger in ungulates and humans, in which it anchors powerful gluteal muscles. Monotremes and marsupials also possess a fourth pair of bones, the prepubes or "marsupial bones", which extend forward from the pubes, and help to support the abdominal muscles and, in marsupials, the pouch.

D. fenestra Leech ( = Apatura chrysus Oberth.) (51c) is a singular species, red-brown being its prevailing ground-colour. In the male the forewing dusted witli blackish in the basal area, there being further a broad black oblique band from the costal margin to the second median branch, behind the band a round spot as in the female, at the hinder angle an elongate spot, anteriorly 2 transparent subapical spots; the distal margin edged with black. Hindwing also margined with black distally, with a median band composed of 6 black spots, the basal and hindmarginal areas grey dusted with black. Underside as in female, ground-colour of the forewing more yellow.

At the same time, the skull and hindlimbs resemble derived troodontids: the deep jugal branch of the maxilla bearing a prominent groove, the sub-triangular antorbital fossa; the relatively long maxillary fenestra; the short jugal branch of the postorbital bone; the long hallux; the slender and short metatarsal II; the "heel" on phalanx II-2; and the large, curved sickle claw. Sinosonasus exhibits a similar condition: the skull is like those of basal troodontids, and the pelvis and hindlimb are like those of derived troodontids. Phylogenetically, Xu and colleagues found Jianianhualong in a polytomy with Sinusonasus and several other intermediate troodontids. The strict consensus tree recovered is reproduced below.

Thliptosaurus was found to be a member of the clade Emydopoidea in the family Kingoriidae, closely related to the genera Kombuisia and Dicynodontoides. Thliptosaurus shares with other kingoriids a dentary plate that occludes and obscures the mandibular fenestra, an arcing anterior process of the lacrimal that contacts the nasal, cutting off the maxilla from contacting the prefrontal bone, and an absence of the postfrontal bone (also shared with other kistecephalians). It shares an extremely reduced pineal foramen with the kingoriid Kombuisia frerensis and cistecephalid Kawingasaurus. However, it is distinguished from these genera by having a moderately broad intertemporal bar, intermediate in width between that of Kombuisia and Kawingasaurus.

The caudal process of each parietal defined the upper edge of a large hole in the skull known as the temporal fenestra, while the rear edge of this hole was formed by the squamosal bone. Like the parietals' caudal processes, the squamosals were similarly widened and relatively unornamented. On the other hand, the jugal (cheek bone) had large, conical spines with rounded tips. Although a lack of spines on the parietals and squamosals may indicate that the Glaurung specimens were juveniles, the well-developed jugal spines indicates that a more likely explanation is that they were legitimate distinguishing features of adult members of the genus.

The orbits (eye sockets) were relatively small. The postorbital bone, which formed the upper rear edge of each orbit, also had a rear branch which underscored a portion of the parietal horns and formed part of the upper edge of the temporal fenestra. The teeth were fewer in number compared to other weigeltisaurids, and the teeth towards the rear part of the mouth were flattened near their tips. Based on the small size of the orbits, their elevated position relative to the rest of the skull), and the wideness of the squamosals, it is likely that Glaurung had a lower, broader skull than other known weigeltisaurids.

Autapomorphies of Jiangchangnathus include: a convex top margin of the lower jaw; a large front branch of the jugal; and the first three pairs of teeth of the lower jaws pointing strongly forwards. Its describers found it to share several features with Scaphognathus, including a high front end of the lower jaws, a pear-shaped lower temporal fenestra with the broad end below and teeth in the maxilla of the upper jaw that have a space equal to that of three toothsockets between them. Additionally, undescribed fossils of a pterosaur referred to Jianchangnathus suggest that the color of its pycnofibers was brown.Li, Q., J.A. Clarke, K.-Q.

Braincase bones have also been preserved in one specimen. The occipital condyle, which was formed by the basioccipital bone, projected from the rest of the skull (in contrast with Archeopelta), and the paired exoccipital bones which lied upon it did not contact each other (similar to other doswelliids). While Doswellia had a pronounced peg-like extension on the rear surface of the supraoccipital bone, Jaxtasuchus only had a vertical ridge. The only preserved bone of the lower jaw is the angular, which has a concave upper edge that may have formed the base of a mandibular fenestra (a hole in the jaw common to most archosauriforms but absent in Doswellia).

The relationship between Limnoscelis and amniotes was later expanded upon, with several features of the skull of Limnoscelis suggesting that it might not only be representative of the ancestor of all amniotes, but representative of the pre-synapsid condition as well. These included a large supratemporal bone contacting the postorbital anteriorly, and a line of weakness between the postorbital, supratemporal, and squamosal bones which could eventually develop into the temporal fenestra of synapsids. However, several authors argued against the validity of these characters. Skull cast of L. paludis Many recent studies have focused on the placement of Limnoscelis and the Diadectomorpha relative to Amniota and Synapsida.

The jugals flare out sideways, forming 'horns' proportionally wider than in any other known Psittacosaurus species except P. sibiricus and P. lujiatunensis. Because of the flared cheeks, the skull is actually wider than it is long. A smaller 'horn' is present behind the eye, at the contact of the jugal and postorbital bones, a feature also seen in P. sibiricus. The mandible (lower jaw) lacks the hollow opening, or fenestra, seen in other species, and the entire lower jaw is bowed outwards, giving the animal the appearance of an underbite. The skull of an adult P. sinensis can reach 11.5 centimeters (4.5 in) in length.

The lower jaw was slender and had no mandibular fenestra, a hole in the side of the lower jawbone commonly seen in archosaurs. The teeth were small but sharp, suited for its diet of small vertebrates and possibly other small animals, such as insects. Its frontmost teeth (those on the premaxilla) were unserrated, unlike those further back in the jaw which were flattened and more strongly recurved.Stromer, E., 1934, "Die Zähne des Compsognathus und Bemerkungen über das Gebiss der Theropoda", Zentralblatt für Mineralalogie, Geologie und Paläontologie, Abteilung B, Jahrgang 1934: 74–85 Scientists have used these dental characteristics to identify Compsognathus and its closest relatives.

Additional Deinonychus skull material and closely related species found with good three-dimensional preservation show that the palate was more vaulted than Ostrom thought, making the snout far narrower, while the jugals flared broadly, giving greater stereoscopic vision. The skull of Deinonychus was different from that of Velociraptor, however, in that it had a more robust skull roof, like that of Dromaeosaurus, and did not have the depressed nasals of Velociraptor. Both the skull and the lower jaw had fenestrae (skull openings) which reduced the weight of the skull. In Deinonychus, the antorbital fenestra, a skull opening between the eye and nostril, was particularly large.

Abelisaurid skulls were also strengthened in many areas by bone mineralized out of the skin, creating the characteristic rough texture of the bones. This is particularly true of Majungasaurus, where the nasal bones were fused and thickened for strength. On the other hand, the lower jaw of Majungasaurus sported a large fenestra (opening) on each side, as seen in other ceratosaurs, as well as synovial joints between certain bones that allowed a high degree of flexibility in the lower jaw, although not to the extent seen in snakes. This may have been an adaptation to prevent the fracture of the lower jaw when holding onto a struggling prey animal.

The bottom margin of the jugal bears a strong flange beneath the level of the infratemporal fenestra; this is also seen in Equijubus, Probactrosaurus, Protohadros, and several other hadrosauroids. Connecting to the jugal from above is the postorbital, which has a roughened surface where it borders the eye sockets (like Protohadros), but the side of the bone is otherwise smooth. At the back of the skull, the quadrate articulates with the squamosal with a joint that is D-shaped when viewed from the top. The left and right squamosals would have contacted each other extensively, being only separated at the back by a small process of the parietal.

Skull cast of BRSMG LEGL 0004 with the snout and lower jaw restored The head of Scelidosaurus was small, about twenty centimetres long, and elongated. The skull was low in side view and triangular in top view, longer than it was wide, similar to that of earlier ornithischians. The snout, largely formed by the nasal bones, was flat on top. Scelidosaurus still had the five pairs of fenestrae (skull openings) seen in basal ornithischians: apart from the nostrils and eye sockets which are present in all basal dinosaurs, the fenestra antorbitalis and the upper and lower temporal fenestrae were not closed or overgrown, as with many later armoured forms.

Several features indicate that Smok is an archosaur, including serrated teeth, a contact between the jugal and quadratojugal bones at the back of the skull, a hole in front of the eye socket called the antorbital fenestra, maxillae bones in the upper jaw that connect along their palatal processes, and a rounded projection on the upper part of the femur bone. The braincase of Smok includes many derived (advanced) features. The most prominent of these is a funnel-shaped structure on the bottom of the braincase, formed by a very wide, rounded basisphenoid bone. A deep notch called the basisphenoid recess cuts into the back of this funnel.

The ancestor of diapsids is considered to have possessed a skull with two openings in the temporal region – upper and lower temporal fenestra on each side of the skull bounded by complete arches. The upper jaw is firmly attached to the posterior of skull. This makes for a very rigid, inflexible construction. The skull of the tuatara resembles this condition However, the lower temporal bar (sometimes called the cheek bone) is incomplete in some fossil Rhynchocephalia indicating that its presence in the tuatara is secondary The tip of the upper jaw is beak-like and separated from the remainder of the jaw by a notch.

The pre-antorbital fenestra, a small opening in front of or beneath the antorbital opening, is well developed in taxa like Diplodocus and Tapuiasaurus, is nearly absent, like in Camarasaurus and Euhelopus. There were about 12-13 total teeth in the maxilla of Europasaurus, fewer than in more basal taxa (16 teeth in Jobaria and 14-25 in Atlasaurus), but falling within the range of variation in Brachiosauridae (15 in Brachiosaurus to 10 in Abydosaurus). All of the unworn teeth preserved display up to four small denticles on their mesial edges. A small amount of the posterior tooth crowns are slightly twisted (~15º), but much less than in brachiosaurids (30-45º).

At the back, the frontal contacts the parietal bone; here, there is a very visible and wide suture that is slightly concave relative to the front of the skull, and the opening of the parietal eye is located in the middle of this suture. The back halves of the sides of the frontal bear rounded ridges. The postorbital bone has three branches, with the front and interior edges of the bone being concave when viewed from the top, while the outer edge was mostly straight. On the postorbital, the interior edge bears a projection around its midpoint, and forms the front margin of the supratemporal fenestra.

The flat and heavily sculptured skull roof is formed by the paired frontal bones above the eyes and the parietal bones above the temporal fenestra. The connection between the frontal pair and the parietal pair is W-shaped, with each parietal having a triangular forward point which penetrates each frontal. A similar connection is also present at the front edge of the frontals, where each frontal is bisected by the rear tip of each nasal bone. Similar to proterochampsians and a few types of archosaurs (crocodylomorphs, dinosaurs, and shuvosaurids), Vancleavea does not possess a postfrontal, a small wedge-like bone which sometimes occupies the rear upper corner of the orbit.

The outer edge of each pterygoid connected to a small, rectangular palatine bone and the longer ectopterygoid, which lies immediately behind it. The palatine and ectopterygoid possessed very large fangs, with two on the palatine and six on the ectopterygoid. Very little of the braincase is well preserved, with the exception of the blade-like parasphenoid which extends forwards along the midline of the skull and divides most of the pterygoids from each other. The lower jaw of Neopteroplax possessed typical embolomere features such as two large meckelian fenestra (holes visible on the inner surface of the jaw), but it also has a few unique and diagnostic traits.

A morphometric study performed by Jason Downs and co-authors highlights certain characteristics that indicate juvenility in Bothriolepis, including a moderately large head and moderately large orbital fenestra—both of which are characteristics also recognized by Erik Stensio in 1948 in the smallest B. canadensis individuals. Several other features that Stensio marked indicative of young individuals can also be seen exhibited in the Catskill sample. These features include "delicate dermal bones with ornament consisting of continuous anastomosing ridges rather than tubercles, a dorsal trunk shield narrower than long and with a continuous and pronounced dorsal median ridge, and a pre- median plate that is wider than it is long".

B. panderi fossil from Russia B. tungseni from China Originally described by Weems et al. in 1981, this species, Bothriolepis virginiensis, is from the "Chemung", near Winchester, Virginia. Several traits found in B. virginiensis can also be found in other species of Bothriolepis, (especially B. nitida), including posterior oblique cephalic sensory line grooves that meet relatively far anteriorly on the nuchal plate, relatively elongated orbital fenestra and a low anterior-median-dorsal crest. Characteristics that distinguish B. virginiensis from other species include but are not limited to fused head sutures, fused elements in adult distal pectoral fin segments and long premedian plate relative to headshield length.

It bears ten teeth. In the 1998 description a part of the splenial was mistaken for a supradentarium and the angular was misidentified as the surangular because in the fossil it had been displaced upwards, creating the false impression an external mandibular fenestra, an opening in the outer side of the jaw, would be present. Scipionyx has five teeth in the premaxilla, seven in the maxilla and ten in the dentary of the lower jaw for a total of twenty-two per side and a grand total for the head of forty-four. The number of five premaxillary teeth is surprising, as a total of four is normal for compsognathids: otherwise, only some Carnosauria have five.

Life restoration with hypothetical skin covering Although very large for a dicynodont, Lisowicia still closely resembles other Triassic stahleckeriids, such as its close relative Placerias from North America. It was a heavily built quadruped with a rotund, barrel shaped body, a large head with beaked jaws and a short neck, stocky limbs, and a very short tail. The skull is incomplete and known only from various isolated individual pieces, but they are enough to determine that it had a similar skull to other stahleckeriids. The temporal fenestra were large, and the back of the skull was drawn into a high crest between them, providing extensive jaw muscle attachment at the back of the skull.

The bone separated the orbit from the antorbital fenestra, forming the upper and lower rear margins of the latter with two processes that enclosed a 40-degree angle; similar to Baryonyx, where it enclosed 35 degrees. Unlike in Baryonyx, Irritators lacrimal did not form a bony horn core. The prefrontal bones were large and sturdy, while the thinner bones, situated behind them, were smooth and concave on top; both of these bones formed the upper rim of the orbit. restoration combining specimens of Irritator and Angaturama A thin sagittal crest, constructed from the elongate nasal bones, extended along the skull midline before stopping just above the eye in a slightly flattened bulge.

Much of the upper margin of the orbit was formed by the of the ; this bone, however, did not contribute to the front margin of the at the rear end of the skull roof. Instead, this front margin was formed by the and , with the front part of the parietal being forked to connect with the latter. Between the parietal and the supraoccipital, which follows behind the parietal at the back of the skull, was another opening, the postparietal fenestra, which was large in Sarahsaurus. A unique feature of the genus can be found on the underside of the braincase, where a shallow ridge spanned between the , bony downwards projections of the braincase that brace the latter against the .

Gasparinisuchus differs from other peirosaurids in having a broad snout and in lacking an antorbital fenestra. Although overlapping materials between the Gasparinisuchus and P. torminni limited to the premaxilla and the dentition, Gasparinisuchus can be differentiate from Peirosaurus on the basis of its broad, rounded rostrum, anteroposteriorly short premaxilla, reduced perinareal fossa, and short premaxillary interdental spaces. Peirosaurus is known from the late Maastrichtian (latest Cretaceous) of Brazil, and the presence of MOZ 1750 PV in Argentina was originally taken as evidence for a link between Brazilian and Argentinian Late Cretaceous faunas. The removal of MOZ 1750 PV from the genus Peirosaurus suggests that the older Argentinian and younger Brazilian faunas were mostly distinct.

The palatine bones are wide at the front and form rough, rugose pads on the roof of the mouth, also likely covered in keratinous horn. The frontals are wide, and so the eyes sit down on the side of the head and face outwards. The postorbital bars closing off the back of the orbits are short, and so the skull (and the temporal fenestra) appear relatively narrow from above for a dicynodont. The pineal foramen (the opening for the "third eye"), bordered by the preparietal in front and the elongated parietal bones behind, is oval and sits flat on the skull, and noticeably varies in size between the two known specimens (0.96 cm and 1.33 cm in length).

Although the bones bordering the lower temporal fenestra (an opening behind the orbit) were incomplete, it appears to have been elongated and slit-like (as in Tupuxuara and Tapejara). Life restoration of a T. sethi pair in flight The palatal area at the tip of T. sethi's snout was a sharp ridge, similar to the keel seen on the upper surface of the mandibular symphysis where the two halves of the lower jaw connected. Small slit-like foramina (openings) on the lower side edges of the ridge indicate that it had a horny covering in life, similar to Tupandactylus. The lower edge of the area was somewhat curved, which probably created a small gap when the jaws were closed.

Reconstructed skeleton of the related genus Tupuxuara in the American Museum of Natural History The classification of Thalassodromeus and its closest relatives is one of the most contentious issues regarding their group. Kellner and Campos originally assigned Thalassodromeus to the family Tapejaridae, based on its large crest and large nasoantorbital fenestra. Within this clade, they found that it differed from the short-faced genus Tapejara but shared a keel on the palate with Tupuxuara. Kellner elaborated on the relationships within Tapejaridae in 2004, and pointed out that Thalassodromeus and Tupuxuara also shared a crest consisting primarily of bone; the crest had a large component of soft tissue in other members of the group.

The quadratojugal formed an obtuse angle that framed the lower rear part of the lateral temporal fenestra, different from the condition seen in diplodocids. and in top (left) and rear views (right) The braincase is mostly hidden from view by overlaying bones, with only the (rear part) being exposed. The uppermost bone of the occipital region is the , which in Bajadasaurus was completely fused to the bone below and featured a distinct and narrow longitudinal ridge, the . The , a pair of openings between the parietal and the occipital region, were extended medially (towards the mid-plane of the skull), which is an autapomorphy of Bajadasaurus (a unique feature not found in closely related genera).

Reconstructed profiles of three Brazilian species; from top to bottom, Tapejara wellnhoferi, Tupandactylus navigans, and Tupandactylus imperator Tapejarids were small to medium-sized pterosaurs with several unique, shared characteristics, mainly relating to the skull. Most tapejarids possessed a bony crest arising from the snout (formed mostly by the premaxillary bones of the upper jaw tip). In some species, this bony crest is known to have supported an even larger crest of softer, fibrous tissue that extends back along the skull. Tapejarids are also characterized by their large nasoantorbital fenestra, the main opening in the skull in front of the eyes, which spans at least half the length of the entire skull in this family.

A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group. According to Ezcurra (2007), and Bristowe and Raath (2004) Coelophysis can be distinguished based on the following features: the absence of an offset rostral process of the maxilla; the quadrate is strongly caudally; a small external mandibular fenestra, which is 9–10% of the mandibular length; and the anteroposterior length of the ventral lacrimal process is greater than 30% of its height.

The surangular was long and sword-shaped, the angular was wing-like in shape, the prearticular was narrow and curved, and the splenial was thin and triangular in outline. The external mandibular fenestra, an opening at the outer side of the mandible, was larger than that of Erlikosaurus because the surangular was shallow from top to bottom. Frontmost dentary teeth, showing folded (lf) and accessory (ad) Segnosaurus had the fewest teeth in the dentary; 24 in each half determined from the number of sockets, as well as the largest teeth known among therizinosaurs. The dentary teeth were foliodont (leaf-shaped) and bore enlarged, relatively tall, sideways compressed crowns with a slight recurvature at the upper margin of the tips.

In 2007, several autapomorphies, unique derived traits, were established. The process of the praemaxilla, obliquely protruding to above and behind in the bony nostril, does not have a groove or depression on its outer side contrary to the situation with Triceratops; this process is exceptionally wide in side view; it also reaches above the level of the lower border of the fenestra interpraemaxillaris. The episquamosals, the epoccipitals of the squamosal, thus the skin ossifications lining and often protruding from the edge of the frill, have an extremely elongated base, and are flattened and spindly, touching each other as with Torosaurus utahensis. Near the lower edge of the squamosal a clearly demarcated groove or depression is present.

Antiarchi ("Opposite anus") is an order of heavily armored placoderms. The antiarchs form the second-most successful group of placoderms after the arthrodires in terms of numbers of species and range of environments. The order's name was coined by Edward Drinker Cope, who, when examining some fossils that he thought were armored tunicates related to Chelysoma, mistakenly thought that the orbital fenestra (i.e., the hole in the headshield for the eyes, nose and pineal foramen) was the opening for the mouth, or oral siphon, and that the opening for the anal siphon was on the other side of the body, as opposed to having both oral and anal siphons together at one end.

Proburnetia, a biarmosuchian with strange bumps and bosses on its skull, from the Late Permian of Russia The biarmosuchian skull is very similar to the sphenacodontid skull, differing only in the larger temporal fenestra (although these are still small relative to later therapsids), slightly backward-sloping occiput (the reverse of the pelycosaur condition), reduced number of teeth, and single large canine teeth in both upper and lower jaws, and other features (Carroll 1988 pp. 370, Benton 2000 p. 114). In later specialised Biarmosuchia, these resemble the enlarged canines of the Gorgonopsia. The presence of larger jaw-closing muscles (and hence a stronger bite) is indicated by the flaring of the rear of the skull where these muscles were attached.

3 like reptiles), fibrous lamellar cortical bone, a temporal fenestra (a hole on the temporal bone), deeply-set teeth, and a secondary palate (which separates the mouth from the nasal cavity, but gorgonopsians may not have had this). Aelurosaurus felinus showing tooth arrangement, dual canines, and canine root depth Like many mammals, gorgonopsians were heterodonts, with clearly defined incisors, canines, and postcanine teeth homologous with premolars and molars. They had 5 incisors in the upper jaw (for most, the first 3 were the same size as each other, and the last 2 were shorter) and 4 on the bottom. In the majority of gorgonopsians, the incisors were large, and the upper canines were elongated into sabres, much like those of later sabre- toothed cats.

However, none of the possible positions are within the Paracrocodylomorpha, meaning that Parringtonia and Erpetosuchus are not closely related to Crocodylomorpha. Below are the possible positions within Nesbitt's phylogeny, marked by dashed lines: The exclusion of Gracilisuchus and Turfanosuchus results in a more resolved topology, placing Erpetosuchidae at the base of Suchia as the sister taxon of aetosaurs plus Revueltosaurus clade. This relationship is weakly supported by only the two character states: posterior portion of the maxilla ventral to the antorbital fenestra expands dorsoventrally and two paramedian pairs of osteoderms. When E. granti was solely used to represent Erpetosuchidae, Gracilisuchus and Turfanosuchus were recovered as basal suchians, in polytomy with Ticinosuchus plus Paracrocodylomorpha and E. granti plus (aetosaurs plus Revueltosaurus) clade.

In these early forms, the connection with the vertebral column is not complete, with a small pair of ribs connecting the two structures; nonetheless the pelvis already forms the complete ring found in most subsequent forms. In practice, modern amphibians and reptiles have substantially modified this ancestral structure, based on their varied forms and lifestyles. The obturator foramen is generally very small in such animals, although most reptiles do possess a large gap between the pubis and ischium, referred to as the thyroid fenestra, which presents a similar appearance to the obturator foramen in mammals. In birds, the pubic symphysis is present only in the ostrich, and the two hip bones are usually widely separated, making it easier to lay large eggs.

The skull of Rukwasuchus possesses several autapomorphies which distinguished it from other crocodyliforms. These include the presence of a mediolaterally narrow, elongate, and septate internal narial fenestra located anteriorly on the pterygoid, the presence of a markedly depressed posterior border of the parietal that excludes the supraoccipital from the dorsal cranial table, and a ventrally directed descending process of the postorbital with a well-developed posteroventral process. The morphology of the skull and isolated teeth suggests close relations to the peirosaurid Hamadasuchus rebouli from the middle Cretaceous Kem Kem Beds of Morocco. Rukwasuchus is the only known sub-Saharan peirosaurid from Africa, thus representing the only link between middle Cretaceous southern vertebrate faunas and much more abundant and taxonomically diverse faunas from northern Africa.

Size of Jianianhualong compared to human hand The conjunction of basal and derived features as distinct regions of the body in Jianianhualong and Sinosonasus represent a possible case of mosaic evolution, in which evolutionary selection acts upon distinct "modules" of the body. Indeed, the pattern in which basal and derived features are present seems to follow the domains of the body that are regulated by Hox genes, which have previously been discussed in the context of pterosaurs such as Darwinopterus. However, this hypothesis is weakened by the presence of characteristics in both troodontids that do not follow the pattern. In Jianianhualong, for instance, the large antorbital fenestra, long tooth row of the maxilla, and finely-serrated teeth represent basal characteristics in an otherwise derived skull.

Descriptions of material from Erpetosuchus in the early 2000s were accompanied by further analyses incorporating Gracilisuchus. In a 2000 description of North American material, Paul Olsen, Hans-Dieter Sues, and Mark Norell recovered Gracilisuchus as more derived than Stagonolepis but more basal than Postosuchus, Erpetosuchus, and crocodylomorphs. Later, in a 2002 revision of the genus, Benton and Walker found contrasting hypotheses for the position of Gracilisuchus: as being more derived than a group containing Ornithosuchus and rauisuchians (Saurosuchus, Batrachotomus, Prestosuchus); or being in a polytomy with Ornithosuchus and rauisuchians. In both cases, it was more basal than the same group in Olsen and colleagues' analysis, being united by a ridge on the squamosal bone above the supratemporal fenestra and the absence of a foramen on the quadrate.

Holtz (in 1994) erected the clade Bullatosauria, uniting Ornithomimosauria (the "ostrich-dinosaurs") and Troodontidae, on the basis of characteristics including, among others, an inflated braincase (parabasisphenoid) and a long, low opening in the upper jaw (the maxillary fenestra). Features of the pelvis also suggested they were less advanced than dromaeosaurids. New discoveries of primitive troodontids from China (such as Sinovenator and Mei), however, display strong similarities between Troodontidae, Dromaeosauridae and the primitive bird Archaeopteryx, and most paleontologists, including Holtz, now consider troodontids to be much more closely related to birds than they are to ornithomimosaurs, causing the clade Bullatosauria to be abandoned. One study of theropod systematics by members of the Theropod Working Group has uncovered striking similarities among the most basal dromaeosaurids, troodontids, and Archaeopteryx.

Some of these shared features include relative size and shape of the temporal fenestra, lateral swelling of the maxilla in the caniniform region and five premaxillary tooth positions (not reported in other mycterosaurines). Though M. efremovi and M. romeri share many distinct features, there are four main morphological differences between these specimens that deem a taxonomic distinction at the species level (differences insufficient for distinction above species level): # The presence of short dorsal premaxillary processes (that do not extend to either the posterior narial margin or the posterior separation of the premaxillae by the nasals) # More posteriorly extensive maxilla # Fewer tooth positions on the maxilla # Contact between the postorbital and supratemporal bones M. efremovi is also larger than the largest known specimen of M. romeri.

Due to the limited material known of Eohyosaurus, the holotype partial skull was scanned in the Museum für Naturkunde, Berlin, focusing on its tooth rows and endocranium due to being too large to be scanned completely. The computed tomography data was provided to the Iziko South African Museum, to be archived along with the holotype. Eohyosaurus possesses one autapomorphy, a unique trait among Rhynchosauria, a jugal bone with elongate dorsal portion that forms the entire front margin of the infratemporal fenestra and that articulates from the front with the entire back margin of the elongated bottom portion of the postorbital bone. Other traits that together comprise a unique combination of characters include some traits that are shared with Howesia and Rhynchosauridae, but not with Mesosuchus.

The skulls of adult Pterodactylus were long and thin, with about 90 narrow and conical teeth. The teeth extended back from the tips of both jaws, and became smaller farther away from the jaw tips, this was unlike the ones seen in most relatives, where teeth were absent in the upper jaw tip, and were relatively uniform in size. The teeth of Pterodactylus also extended farther back into the jaw compared to close relatives, and some were present below the front of the nasoantorbital fenestra, which is the largest opening in the skull. Another autapomorphy that Pterodactylus has is that the skull and jaws were straight, which are unlike the upwardly curved jaws seen in the related ctenochasmatids. restoration of BMMS 7, the largest known Pterodactylus specimen.

By the Late Permian many other groups of tetrapods had entered that niche, and increased competition among herbivores likely resulted in the eventual extinction of diadectids. Alveusdectes may have been able to persist because the fauna of north China seems to have been isolated from other Laurasian faunas during the Late Permian, meaning that fewer herbivores were competing for the same ecological space. Alveusdectes differs from other diadectids in having a pair of large holes at the back of its skull called suborbital fenestrae, which would have been attachment points for large jaw muscles. Other defining features include a large fourth tooth in the dentary bone of the lower jaw and an elongate Meckelian fenestra positioned near the back of the jaw.

Distinguishing features of Liaoningotitan include a ventral margin of the maxilla that is convex, an upper tooth row that is short and anteriorly positioned; an anterior extension of the jugal that nearly reaches the level of the anterior margin of the antorbital fenestra; a basally constricted quadrate wing of the pterygoid; imbricated upper teeth, with narrow spatulate crowns that are D-shaped in cross section, and no labial grooves or denticles; nine reduced and un-imbricated lower teeth; asymmetric lower tooth crowns which are elliptical-like in cross section, with lingual grooves and ridges and a lingually bulbous basal crown; a proximal expansion of the humerus that is about 54.9% the length of the humerus; and an ilium with a pointed preacetabular process.

The skull of a juvenile Pinacosaurus grangeri on the left, compared with those of Anodontosaurus lambei The visible sutures of the skull elements in juvenile specimens allowed for the first time to determine their precise arrangement. They generally consisted of indistinctly formed simple shapes. Several skull openings like the antorbital fenestra and the temporal fenestrae apparently closed at a very young age for they are no longer visible even in the juveniles found. The squamosal horn does not cover the entire squamosal, creating the illusion that an additional skull bone is present in front of the horn. Maryańska in 1977 thought that this was a tabular bone, otherwise unknown in dinosaurs, proving that the Ankylosauria had independently evolved from the Aetosauria, a hypothesis today entirely discarded. Godefroit in 1999 called it a "secondary dermal squamosal".

Additionally, K. langenbergensis differs from other species in lacking teeth with low crowns; having a longer maxillary symphysis; having a crest on the side of the downward-projecting process of the postorbital; having overlap between the postorbital and the front of the squamosal; and a rectangular parietal that does not form part of the supratemporal fenestra. In the 2017 description of K. langenbergensis, Schwarz et al. used the 2015 phylogenetic dataset of Alan Turner, which was revised to remove irrelevant characteristics, add K. langenbergensis and T. grandinaris, and correct flaws in the coded traits of K. guimarotae (due to low-resolution images, inaccuracies in the original reconstruction, and the acquirement of new data). The phylogenetic trees recovered by this analysis consistently found that Atoposauridae, represented by Knoetschkesuchus, Theriosuchus, and Alligatorium, forms a monophyletic clade.

A 2017 phylogenetic analysis conducted based on the dataset of McPhee et al., published in 2015 with the description of Pulanesaura, found that Xingxiulong was a basal member of the group Sauropodiformes once Blikanasaurus was removed from the dataset. Within this group, it is closest to the contemporary Jingshanosaurus. Traits that are shared by Xingxiulong and Jingshanosaurus include the infratemporal fenestra being placed entirely behind the eye socket; the scapula being at least 20% as wide as it is long; the pubic apron, or the bottom of the pubis, having a concave outer face; the expansion at the bottom of the apron being at least 15% the length of the entire bone; and the angle between the femoral head and the cross-sectional axis of the femoral shaft being about 30°.

Thecodonts are characterized by certain shared primitive features, such as the antorbital fenestra (an opening on each side of the skull between the eye sockets and the nostrils) and teeth in sockets. The name thecodont is Greek for "socket-tooth", referring to the fact that thecodont teeth were set in sockets in the jawbones; an archosaurian characteristic that was inherited by the dinosaurs. While the taxon Thecodontia is obsolete, the term thecodont remains in use as an anatomical description of teeth in bony sockets; in addition to species formerly in this group (such as crocodiles and dinosaurs), mammals also possess thecodont dentition, which evolved independently. They constitute an evolutionary grade of animals, a "wastebasket taxon" for any archosaur other than a crocodilian, a pterosaur, or a dinosaur (any basal archosaur).

They instead found that Dilophosaurus was a coelophysoid, with Cryolophosaurus and Sinosaurus being more derived, as basal members of the group Tetanurae. Belgian paleontologist Christophe Hendrickx and colleagues defined the Dilophosauridae to include Dilophosaurus and Dracovenator in 2015, and noted that while general uncertainty exists about the placement of this group, it appears to be slightly more derived than the Coelophysoidea, and the sister group to the Averostra. The Dilophosauridae share features with the Coelophysoidea such as the subnarial gap and the front teeth of the maxilla pointing forwards, while features shared with Averostra include a fenestra at the front of the maxilla and a reduced number of teeth in the maxilla. They suggested that the cranial crests of Cryolophosaurus and Sinosaurus had either evolved convergently, or were a feature inherited from a common ancestor.

Schoch & Milner (2014) provide nine characters in their diagnosis of Acheloma: (1) toothed crest on the vomer extending medial to the internal naris; (2) constricted otic notch with nearly horizontal ventral margin; (3) preorbital region twice as long as the skull table; (4) naris twice as long as the orbit; (5) posterior skull table wide and posterolaterally expanded; (6) skull margin widens at level of and posterior to orbit; (7) palatine and ectopterygoid with tall fangs; (8) large intervomerine fenestra; and (9) choana elongate and curved with a Y-shaped contour. Acheloma cumminsi and A. dunni are distinguished by the purported absence of lateral exposures of the palatine (LEP) and the ectopterygoid (LEE) in A. cumminsi, but these exposures were subsequently identified following re-examination of the holotype of this taxon.

These include: > # Reduced antorbital fenestra # A prominent pre-infratemporal shelf # A > septomaxilla forming the anterolateral half of the external naris # > Thickened rim of the orbit # Inflated posterior part of nasal # Thickened > dorsal osteoderms Historically, studies of Redondasaurus have been hampered by small number of specimens available, of which only four skulls were recognized in literature. Recently, several Norian-Rhaetian phytosaur skulls have been referred to Redondasaurus, which has brought the number of recognized skulls to ten. These new specimens encompass a range of sizes from hatchlings to adults and possibly include the first evidence of sexual dimorphism in the taxon. Sexual dimorphism within Redondasaurus was also recognized by J. Spielman and S.G. Lucas on May 11, 2012, at the 64th Annual Meeting of the Geological Society of America.

Forfexopterus would have been large for an archaeopterodactyloid. The skull was low and long, measuring in length; it appears that no crest was present on either jaw. Forfexopterus is unique among archaeopterodactyloids in that the first phalanx bone of the wing finger was shorter than the second but longer than the third. In addition, it exhibits a unique combination of traits: it has in total approximately 120 long, slender teeth, which span from the tip of the jaw to 1/3 along the length of the skull (stopping before the nasoantorbital fenestra); the crest on the sternum, known as the "cristospine", is long; the location where the coracoid attaches to the sternum is further forward on the right side than the left; and the coracoid bears a flange.

Although the posterior end of the lower jaw is not preserved in L. maghrebensis, in L. thaumastos the coronid process is rugose, low and broad transversely, thickened by the surangular on the lingual side of the jaw, possibly signifying the attachment of powerful muscles to close the long, heavy jaws - a task that would be difficult underwater due to the large surface area between them. The external mandibular fenestra is very much reduced, forming little more than a slit. There is an unusually small adductor fossa just in front of the saddle-shaped articular facet of the glenoid; on the right side this saddle-shaped facet has irregular edges and shows some signs of bone disease, for unknown reasons. The retroarticular process is triangular in cross-section with slightly concave sides.

In most other dicynodonts the jugal is small and restricted under the eyes, but in Ufudocyclops it extends along much of the lateral (outside) face of the zygomatic arch beneath the eyes and cuts off the maxilla, which usually joins to the squamosal on the zygomatic arch. This unusual setup of the jugal also causes the zygomatic arch to noticeably jut out from the skull under the eyes, compared to other kannemeyeriiforms where it gradually curves out away from the skull. In addition, while most kannemeyeriiforms have the front of the orbits formed only by the jugal and the lacrimal bone, Ufudocyclops also has a very small portion of the maxilla between them too. Ufudocyclops is also characterised by the unique 'X'-shaped intertemporal bar on the roof of the skull between each temporal fenestra, where the large jaw muscles attached.

Skull roof Asperoris belongs to a clade or evolutionary grouping of reptiles called Archosauriformes, which includes Archosauria (the clade including living crocodilians and birds) and their extinct, mostly Triassic, relatives. It has several features that place it outside Archosauria with non-archosaurian archosauriforms, including the lack of an antorbital fossa and the possible presence of a postparietal bone at the back of the skull, which is not found in archosaurs. However, it also has features that place it among the closest relatives of archosaurs, including the presence of an antorbital fenestra and the lack of a hole called the parietal foramen on the skull roof. Asperoris shares with a group of archosauriforms called erythrosuchids the presence of slot in the lower part of the nasal bone that fits into a projection of the premaxilla beneath it.

Many early archosauromorphs, including Protorosaurus, tanystropheids, Trilophosaurus, and derived rhynchosaurs, have a blade-like sagittal crest on the parietal bones at the rear part of the skull roof, between a pair of holes known as the supratemporal (or upper temporal) fenestrae. However, in other allokotosaurs, the basal rhynchosaur Mesosuchus, and more crownward archosauromorphs, the sagittal crest is weakly differentiated, although the inner edge of each supratemporal fenestra still possessed a depressed basin of bone known as a supratemporal fossa. Ezcurra (2016) argued that presence of supratemporal fossae and an absence or poor development of the sagittal crest could be used to characterize Crocopoda. He also noted that in almost all early archosauromorphs (and some choristoderes), the parietal bones have an additional lowered area which extends transversely (from left to right) behind the supratemporal fenestrae and sagittal crest (when applicable).

In November of the same year he used it to operate on a patient with chronic otitis who had a labyrinthine fistula. Nylen's microscope was soon replaced by a binocular microscope, developed in 1922 by his colleague Gunnar Holmgren (1875–1954). Gradually the operating microscope began to be used for ear operations. In the 1950s many otologists began to use it in the fenestration operation, usually to perfect the opening of the fenestra in the lateral semicircular canal. The revival of the stapes mobilization operation by Rosen, in 1953, made the use of the microscope mandatory, although it was not used by the originators of the technique, Kessel (1878), Boucheron (1888) and Miot (1890). Mastoidectomies began to be performed with the surgical microscope and so were the tympanoplasty techniques that became known in the early 1950s.

In 2011, Hooley's specimen was redescribed as a distinct genus and species of goniopholidid called Anteophthalmosuchus hooleyi. The genus name means "forward-pointing eye crocodile" because the specimen's eye sockets are positioned high on the skull and angle forward rather than to the side as in most other flat-skulled crocodyliforms, and the species name honors Hooley. Features that distinguish A. hooleyi from Goniopholis crassidens include the lack of a hole in the lower jaw called the mandibular fenestra, very wide supratemporal fenestrae (openings) on the skull table, and a bone above the eye socket called the palpebral that is small and does not extend over the socket as in some other goniopholidids. A. epikrator skull Two specimens from Bernissart, Belgium, collectively referred to as "Dollo's goniopholidid", was referred to A. hooleyi in a 2016 redescription.

Bolt and Lombard were able to classify Sigournea as an early member of Tetrapoda based on the presence of bone surfaces covered in pits and ridges, a single row of dentary teeth, a jaw joint that faces upward, and an open groove for a lateral line along the outer surface of the jaw, and on the absence of teeth on the prearticular bone or enlarged fangs on the coronoids. Sigournea differs from other stem tetrapods in having several holes within a depression called the exomeckelian fenestra on the inner surface of the jaw. The closest relatives of Sigournea within Tetrapoda are unknown. Bolt and Lombard did not include it in a phylogenetic analysis in their 2006 description because they thought the single known jawbone did not possess enough unique anatomical characteristics to elucidate its evolutionary relationships.

The three established autapomorphies of C. bonapartei by Dilkes and Arcucci (2012), are either unknown in P. ischigualastensis or known to differ from it. In fact, two out of the three autapomorphies (a deep well-defined depression in front of the nostril, and an elongated oval supratemporal fenestrae with a back-side directed main axis) are absent in P. ischigualastensis, in which this depression is shallow like in G. reigi, and the supratemporal fenestra is near-triangular and aligned with the long axis of the skull. Thus, Trotteyn and Ezcurra (2014) found no synapomorphies that unite C. bonapartei and P. ischigualastensis exclusively, or support their monophyly within Chanaresuchus, requiring a new generic name for "C." ischigualastensis. The phylogenetic analysis of Trotteyn and Ezcurra (2014) placed C. bonapartei and P. ischigualastensis in a polytomy with G. reigi.

Cerroni and colleagues conducted a phylogenetic analysis to determine the affinities of Tralkasaurus. They found that it possesses synapomorphies of the Abelisauridae: a maxilla with a deep body, low ascending process, and reduced maxillary fossa, covered by foramina and rugosities; fused lining the inside of the maxillary tooth row bearing strong vertical ridges; the subdivision of the infradiapophyseal fossae by the posterior paradiapophyseal laminae; a connection between the transverse processes and parapophyses by the dorsal paradiapophyseal laminae; large transverse processes strongly inclined upwards on the caudal vertebrae; and a thin pubic shaft. They also identified the forward-inclined front margin of the antorbital fenestra and its excavation of the body of the maxilla, the rod-like parapophyses, and the low paradiapophyseal laminae as autapomorphies of Tralkasaurus. Within the Abelisauridae, the position of Tralkasaurus was more poorly resolved.

Additional diagnostic characters were proposed by the authors, but their character-states cannot be determined in other protosuchian taxa. These characters include a width of the mandibular symphysis across the swellings of the caniniform teeth that is almost equal to the anteroposterior length of the symphysis and an anterolateral process of the ectopterygoid with an inverted V-shaped ridge on the dorsal surface. The shortness of the snout relative to the rest of the skull and the presence of a laterally and ventrally open notch between the premaxilla and maxilla indicate that Platyognathus is a member of Protosuchia as defined by Wu et al. (1994). Because the infratemporal fenestra of Platyognathus is very small and the mandibular symphysis extends posteriorly to the level of the seventh to ninth tooth, the genus is thought to be more derived than Orthosuchus.

Restoration of Dorygnathus banthensis; Parapsicephalus has been considered a member of the same genus In 2003, David Unwin, Kenneth Carpenter, and others suggested that Parapsicephalus was actually closer to the roughly contemporaneous Dorygnathus from German deposits. Unwin formally renamed it to the new combination Dorygnathus purdoni. This renaming was adopted by some researchers but not others. However, a 2017 redescription of GSM 3166 noted a number of ways in which Dorygnathus differed from Parapsicephalus: the greater angle of the lacrimal process of the maxilla, the more reduced maxillary process of the premaxilla, the broader angle of the jugal beneath the eye socket, the overall thinner jugal relative to skull height, the more rounded the eye socket, the more oval-shaped supratemporal fenestra, and the convex top of the skull (which is unique among pterosaurs except for dimorphodontians).

Persson considered this material to be enough to clearly differentiate the fossil animal from all other known long-snouted crocodylomorphs, noting that the main distinguishing feature was the nasal bone of Aigialosuchus extending to the fenestra exonarina communis. In 2017, Greenlandic paleontologist Jan S. Adolfssen, Danish paleontologist Jesper Milàn and American paleontologist Matt Friedman noted that a single, rather blunt and wide crocodylomorph tooth from the Faxe quarry in the Middle Danian-aged Faxe Formation at Faxe, Denmark, might be referrable to either Aigialosuchus or to some genus within the Alligatoroidea. A similar tooth also discovered in Early to Middle Paleocene deposits, this time at Gemmas Allé in Copenhagen, in 2014, also accorded well with Persson's description of Aigialosuchus teeth, though it was not referred to the genus due to the lack of a formal comparison to the type material.

In addition, they are many palatal teeth, and the teeth of the upper jaws are numerous (four premaxillary and eleven maxillary teeth) and spatulate with many cuspids. The front teeth, fairly long and slightly recurved, were probably suited to aid in gathering vegetation into the mouth, whereas it is presumed that palatal teeth had to worked in conjunction with a tough and massive muscular tongue as indicated by the presence of a very well- developed hyoid apparatus. Characteristically, Euromycter shows an unusually broad skull, large temporal fenestra, and lack of expansion of the axial neural spine. It can be distinguished from other caseids by the presence of a supernumerary blade-like intranarial bone located posteromedially to the septomaxilla, proportional differences in forelimb and manus, presence of an accessory proximal articulation between metacarpals 3 and 4, medial recurvature of metacarpal, and its manual phalangeal formula of 2-3-4-4-3.

Among the three branches of the jugal, the backwards-directed branch forms an angle of 80° with the upwards-projecting branch, which is similar to Plateosaurus and Thecodontosaurus but much larger than other sauropodomorphs. At the base of the skull, the quadratojugal bears two branches, one pointing forwards and one upwards; they are roughly perpendicular to each other, unlike Lufengosaurus (angle of 45°), Yunnanosaurus (angle of 60°), and Jingshanosaurus (angle of 110°). Above the quadratojugal, the quadrate has two articulating condyles, a subtriangular one facing outward and a more rounded one facing inwards; the latter condyle is placed closer to the bottom, like Lufengosaurus and Yunnanosaurus but not Plateosaurus. At the back of the skull, between the parietals and supraoccipitals, there is a prominently developed postparietal fenestra; the supraoccipital itself slopes forwards at its bottom end so as to round off the base of the skull.

To date, all phylogenetic analyses of Yutyrannus relationships have classified it in the group Tyrannosauroidea. An initial analysis of its relationship to other tyrannosauroids showed that it was more primitive than Eotyrannus in the evolutionary tree, but more advanced than tyrannosauroids such as Dilong, Guanlong and Sinotyrannus. Primitive traits relative to advanced tyrannosaurs included long forelimbs with three fingers and a short foot which was not specialized for running. Advanced traits included a large and deep skull, the outer side of the premaxilla having rotated upwards, a large cuneiform horn on the lacrimal in front of the eye socket, a postorbital process on the back rim of the eye socket, the squamosal and the quadratojugal forming a large process on the back rim of the infratemporal fenestra, short dorsal vertebrae, an ilium with a straight upper rim and an appending lobe, a large pubic foot and a slender ischium.

5 In total, eighteen additional Ranger companies were formed in the next seven months: Eighth Army Raider Company and First through Fifteenth Ranger Infantry Companies (Airborne) and Ranger Infantry Companies A & B. The Army Chief of Staff assigned the Ranger training program at Fort Benning to Colonel John Gibson Van Houten.Lock, John D. and Moore, Harold G. To Fight With Intrepidity: The Complete History of the U.S. Army Rangers 1622 to Present Fenestra Books, 2001 p.286 The program would eventually be split to include a training program located in Korea. 3rd and 7th Ranger companies were tasked to train new Rangers. The 28 October 1950 would see the next four Ranger companies formed. Soldiers from the 505th Airborne Infantry Regiment During the late 1940s the separate, all-black 555th Parachute Infantry Battalion was merged into the 505th AIR to become the regiment's "new" 3rd Battalion.

Some of the most notable features consisted in the strongly vertical pubis and the robustly built skeleton, such as the deep maxilla and femur. The holotype was found lacking traces of feather integument, however, there are strong evidence coming from other relatives that suggest the likely presence of plumage on Achillobator. According to the revised diagnosis by Turner and colleagues in 2012, Achillobator can be distinguished based on the following combination of characteristics and autapomorphies: the promaxillary fenestra is completely exposed, the promaxillary and maxillary fenestrae are elongate and vertically oriented at same level in the maxilla, metatarsal III is wide on the upper end, the femur is longer than the tibia, the pelvis is propubic, the obturator process on the ischium is large and triangular situated on the upper half of ischial shaft, the boot at distal symphysis of pubis is developed in a cranial and caudal aspect.

The most recent revision of the genus is that of Schoch & Milner (2014), who list a combination of seven features and two plesiomorphies: (1) nearly circular outline of skull with curved maxilla; (2) prefrontal and postfrontal separated; (3) preorbital region equal to skull table in length; (4) internarial fenestra present; (5) teeth variably monocuspid and bicuspid; (6) vomer with both medial and lateral fangs; (7) palatine lacking denticles; (8) long supratemporal; (9) postparietal longer than tabular. Most of these features are not unique to Tersomius (the combination being unique), as evidenced by the diagnosis of Anderson & Bolt (2013), who list an elongate tabular and a medial curvature of the maxillary arcade at the position of the quadrate (shared with Doleserpeton, T. texensis, and Micropholis) as diagnostic. The poor understanding of T. mosesi often leads it to be excluded in discussion or diagnosing of the genus.

These wineries include Misson Wines, McKahn Family Cellars, Nottingham Cellars, Murrieta's Well, The Winemakers' Studio, Steven Kent Winery, Wood Family Vineyards, McGrail Vineyards, Cuda Ridge Winery, Retzlaff Winery, Fenestra Winery, Occasio Winery, Stony Ridge/Crooked Vine Cellars, Longevity Wines, Rodrigue Molyneaux Winery, 3 Steves Winery, Big White House/John Evan, Charles R Vineyards, Garre' Winery, Ehrenberg Cellars, The Singing Winemaker, Chouinard Vineyards, Elliston Vineyards, Las Positas Vineyards, Dante Robere Vineyards, Ruby Hill Winery, Rubino Estates, Bodegas Aguirre, Nottingham Cellars, Vasco Urbano Wine Company, Page Mill Winery, and Nella Terra Cellars. Livermore possesses a predominately gravel based soil and lies on a unique east-west orientation, unlike many other winegrowing valleys. Due to a reliable onshore afternoon/evening breeze off of the San Francisco Bay a wide fluctuation in temperature between sites and a large diurnal temperature swing occur. Livermore Valley is considered a Winkler Region III grape growing zone with temperatures comparable to northern Napa Valley appellations such as St. Helena or Calistoga.

Like all zatracheidids, Zatrachys is easily recognized by the presence of a large opening in the snout, the internarial fontanelle or fenestra. Of the three genera of zatracheidids, that of Zatrachys is the largest, extending as far back as to fully divide the nasals and to partially divide the frontals, a unique feature (autapomorphy). Other features that distinguish this genus are the presence of prominent spiky projections from the posterior skull (maxilla and quadratojugal), bosses and ridges on the lower jaw, a supratemporal that borders the otic notch, long and slender tabular horns and short postparietal horns, contact between the palatine and the vomer to fully enclose the choana on the palate, and a U-shaped skull profile intermediate to that of Acanthostomatops (broad and parabolic) and Dasyceps (elongate). Although there are numerous reports of postcranial material attributed to Zatrachys, all of this was referred to species that are now reassigned to other temnospondyl taxa (e.g.

These traits are the presence of large, well-rimmed pits on either side of the dorsal (back) vertebrae, a humerus (upper arm bone) which has a symmetrical proximal portion when seen from the front, and a preacetabular process (front blade) of the ilium (upper hip bone) which has a moderate length, longer than it is high, but not longer than the pubic peduncle. He also noted that in some suchians, the tip of the maxillary bone's posterior process (rear branch), near the rear lower tip of the antorbital fenestra, is actually taller than the middle portion of the rear branch. This trait, formally known as the posterodorsal process of the maxilla, has been considered a synapomorphy of gracilisuchids and is also present in aetosaurs and Qianosuchus. Despite the broad distribution of this characteristic, its absence in some suchians makes it ambiguous whether it qualifies as a synapomorphy of Suchia, or alternatively evolved in several independent lineages within the group.

Size of various spinosaurids (Irritator in purple, first from left) compared with a human Martill and his team originally classified Irritator as a maniraptoran dinosaur in the clade Bullatosauria (a group no longer considered monophyletic), as a close relative to the feathered ornithomimosaurs and troodontids. Given that its dental morphology, particularly long snout, and assumed fin-shaped crest were features unknown in "other" maniraptorans, the researchers erected the new family Irritatoridae within the clade. They recognized Irritators affinities with Spinosaurus, in that they both had similarly shaped and unserrated teeth, but noted that the latter's mandible would not conform with the front of Irritators upper jaw, and that other non-avian dinosaurs like Compsognathus and Ornitholestes also bore no serrations on some or all of their teeth. Some of these claims were questioned in 1996 by Kellner who found that Irritators skull lacked the one autapomorphy (distinguishing feature) diagnosed in maniraptorans at the time, which was having its (cheek) bone forming part of the antorbital fenestra.

Kellner and Campos posited that the crest could have had additional functions, such as display; aided by colour, it could have been used in species recognition, and could also have been a sexually dimorphic feature (differing according to sex), as has been proposed for Pteranodon. In 2006, Martill and Naish found that the crests of Tupuxuara and its relatives developed by the premaxillary portion of the crests growing backwards over the skull-roof (as indicated by the well-defined suture between the premaxilla and the underlying bones). The hind margin of the premaxillary part of this specimen's crest had only reached above the hind margin of the nasoantorbital fenestra, indicating that it was not an adult at the time of death. This suggests that the development of the crest happened late in the growth of an individual, was probably related to sexual display, and the sexual maturity of a given specimen could be assessed by the size and disposition of the crest.

When viewing the Eusthenodon skull in dorsal view, the fenestra exonarina can be seen positioned high and laterally in the snout. Of the three temporal bones that make up the parietal shield present in osteolepiformes (intertemporal, supratemporal, and extratemporal), the presence of the extratemporal bone in a ‘postspiracular’ position, defined as the shift of the bone from a position lateral to the supratemporal to a more posterior-lateral position, is a significant and diagnostic character of the Tristichopteridae clade. The extratemporal bone present in Eusthenodon is notable for its complete postspiracular position resulting in no contact between the supratemporal and extratemporal bones, a condition known only to exist in Eusthenodon. One theory to explain the trend observed in the posterior shift of the extratemporal bone in more derived fishes suggests that the change in head proportions contributed to a more streamlined body shape and enhanced its maneuverability and speed in its aquatic environment.

Ji and Ji (1996) identified many features that set Sinosauropteryx apart from other birds and dinosaurs. They found that it was a small primitive bird with a relatively high skull, blunt rostrum and a slightly high premaxilla; that the antorbital fenestra was elliptical but not enlarged, the dentary was robust, the surangular was narrow and elongated, and the dentition is extremely well developed and acute; that there are over 50 extremely elongated caudals, constituting 60% of the body length, and the forelimb is extremely short with a short and thick humerus; the pubis was elongated and extremely inflated at its distal end and the ischium is broad; the hind limb was long and robust, the tibia is only slightly longer than the femur, the tarsals are separated, and the metatarsals are relatively robust with unfused proximal ends; the feathers are short, small, and uniform; many ornament the top of the skull, cervical, and dorsal regions, in addition to the dorsal and ventral caudal region.

David M. Unwin has also referred miscellaneous limb bones and vertebrae from the somewhat older Kimmeridge Clay of Dorset, England to the genus; these finds at the time marked the earliest appearance of short- tailed pterosaurs in the fossil record. Bennett suggested in 1996 that Germanodactylus represented adults of Pterodactylus, but this has been rejected by further studies, including his own. Bennett's 2006 reappraisal of Germanodactylus found both species to be valid and included within the genus, with G. cristatus known from four specimens, including two juveniles, and G. rhamphastinus from two specimens. The genus differs from other pterosaurs by a combination of characteristics including a sharply pointed jaw tip, four to five premaxillary teeth, and eight to twelve maxillary teeth per side of the upper jaw, robust maxillary teeth that, unlike in Pterodactylus, are not reduced in size farther from the tip of the jaw, a naso-antorbital fenestra twice the length of the eye socket, and various proportional differences.

The vestibule is somewhat oval in shape, but flattened transversely; it measures about 5 mm from front to back, the same from top to bottom, and about 3 mm across. In its lateral or tympanic wall is the oval window (fenestra vestibuli), closed, in the fresh state, by the base of the stapes and annular ligament. On its medial wall, at the forepart, is a small circular depression, the recessus sphæricus, which is perforated, at its anterior and inferior part, by several minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve to the saccule; and behind this depression is an oblique ridge, the crista vestibuli, the anterior end of which is named the pyramid of the vestibule. This ridge bifurcates below to enclose a small depression, the fossa cochlearis, which is perforated by a number of holes for the passage of filaments of the acoustic nerve which supply the vestibular end of the ductus cochlearis.

The stapes (stirrup) ossicle bone of the middle ear transmits vibrations to the fenestra ovalis (oval window) on the outside of the cochlea, which vibrates the perilymph in the vestibular duct (upper chamber of the cochlea). The ossicles are essential for efficient coupling of sound waves into the cochlea, since the cochlea environment is a fluid–membrane system, and it takes more pressure to move sound through fluid–membrane waves than it does through air; a pressure increase is achieved by the area ratio of the tympanic membrane to the oval window, resulting in a pressure gain of about 20× from the original sound wave pressure in air. This gain is a form of impedance matching – to match the soundwave travelling through air to that travelling in the fluid–membrane system. At the base of the cochlea, each duct ends in a membranous portal that faces the middle ear cavity: The vestibular duct ends at the oval window, where the footplate of the stapes sits.

The placement of turtles on the reptile evolutionary tree has been a point of contention in the past few decades because of a disagreement between morphological and molecular data. Based on anatomical data alone, turtles appear to fall within Parareptilia, which is a basal clade or evolutionary group within Sauropsida (Sauropsida is the reptile clade). Parareptiles are generally characterized by the lack of temporal openings in their skull (but now most of them are known to have at least a lower temporal fenestra,) and lie outside the main group of reptiles, Diapsida, which includes all other living sauropsids (lizards, snakes, crocodilians, and birds) and is characterized by two pairs of temporal openings. In contrast, molecular data suggests that turtles lie within Diapsida, either as a subset of the Lepidosauromorpha (which includes lizards and snakes)—supported by one microRNA analysis—or the clade Archosauromorpha (which includes crocodilians and birds)—supported by almost all molecular analyses.

Schoch & Milner (2014) listed seven features in the diagnosis of Ecolsonia: (1) tabular and squamosal frame otic fenestra; (2) prefrontal and postfrontal separated (shared with most other trematopids); (3) preorbital region of equal length to posterior skull table; (4) vomer with a posteromedial process meeting the pterygoid (shared with other trematopids); (5) a supratemporal that is twice as long as it is wide; (6) triangular patch of denticles on the parasphenoid (shared with other trematopids); and (7) basipterygoid region unsutured (shared with some other trematopids). Trematopid synapomorphies include the posterior process of the vomer, the denticles on the parasphenoid, and the supinator process of the humerus. A large number of small scales were also found with some specimens of Ecolsonia that probably covered the entire body, a feature similar to that seen in the trematopid Anconastes; these are distinct from the osteoderms of dissorophids that are only associated with the vertebral column.

Caravaggio's early biographer Giovanni Baglione gives the following description of a piece done by the artist for his patron Cardinal Francesco Del Monte: > E dipinse [per il Cardinale Del Monte]… anche un giovane, che sonava il > Lauto, che vivo, e vero il tutto parea con una caraffa di fiori piena > d’acqua, che dentro il reflesso d’ua fenestra eccelentemente si scorgeva con > altri ripercotimenti di quella camera dentro l’acqua, e sopra quei fiori > eravi una viva rugiada con ogni esquisita diligenza finta. E questo (disse) > che fu il piu bel pezzo, che facesse mai. ("He also painted [for Cardinal > Del Monte] a young man, playing the Lute, who seemed altogether alive and > real with a carafe of flowers full of water, in which you could see > perfectly the reflection of a window and other reflections of that room > inside the water, and on those flowers there was a lively dew depicted with > every exquisite care. And this (he said) was the best piece that he ever > painted.)" Giovanni Baglione, Le Vite de’ Pittori, scultori et archtietti, > Roma, 1642, p.

Shen and colleagues identified Liaoningvenator as a member of the Troodontidae based on its numerous, closely spaced teeth that are constricted below the crown; the pneumatic opening on the rear of its quadrate; the oval shape of its foramen magnum; the replacement of neural spines by shallow midline grooves in the vertebrae towards the end of its tail; the tall ascending process on its astragalus; and its asymmetrical and subarctometatarsal (i.e. where the third metatarsal is somewhat pinched by the neighboring metatarsals) foot. They further placed it in the "higher troodontid clade" based on the lack of a bulbous capsule-like structure on the parasphenoid of its palate, and the presence of the promaxillary fenestra on its skull. Based on a phylogenetic analysis modified from a prior analysis by Takanobu Tsuihiji and colleagues in 2016, which was in turn modified from the modification by Gao and colleagues in 2012 of an analysis by Xu Xing and colleagues in 2012, Shen and colleagues found that Liaoningvenator formed a unified group, or clade, with Eosinopteryx, Anchiornis, and Xiaotingia, thus offering contrary evidence to the traditional placement of these taxa as non-troodontid members of the Paraves.