Much like expansion in the maxillae the dentaries expand transversely on the alveolar accommodate multiple rows of teeth. These 6 rows conical peg like teeth occur on medially expanded on both maxillae and dentaries.
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The holotype of Agkistrognathus campbelli, TMP 89.127.6, is a disarticulated skull including a maxilla, premaxilla, vomer, dentaries, angular, splenial, and other unidentified fragments.
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The lower jaw is represented by low dentaries with parallel upper and lower edges. Preserved dentary teeth are variable in shape and serrated similarly to maxillary teeth.
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These are small arboreal frogs which live and breed exclusively on epiphytic bromeliad plants. They have large odontoids ("fangs") on the dentaries. Male Phyllodytes do vocalize, in contrast to Phytotriades.
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Agkistrognathus is a thalattosaurian, a group of marine reptiles with long, paddle-like tails and independently movable digits. Agkistrognathus can be distinguished from other thalattosaurians due to having conical, closely spaced teeth which are smallest in the middle of the jaw and deep dentaries with hooked front ends. These features may have given it a powerful bite . The dentaries are also bifurcated at their posterior ends, with the both forks being the same length but the dorsal one being much deeper.
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Dentaries Assignment of two dentaries to a caseid is based on the shape of the symphyseal area. As in other caseids, the dorsal edge of the dentary bone curves ventrally near the symphysis, and forms an acute angle with the ventral edge of the bone. This results in a substantially more slender dentary bone near the symphysis than in the rest of the bone. As in other caseids, this is related to the presence of a well-developed anterior process of the splenial bone, one that contributes to a large portion of the symphysis medially.
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"New partial dentaries of amphitheriid mammalian Palaeoxonodon ooliticus from Scotland, and posterior dentary morphology in early cladotherians". Acta Palaeontologica Polonica. in press. doi:10.4202/app.00434.2017. It is found in the Forest Marble Formation and the Taynton Limestone Formation.
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The symphysis of the lower jaws has at the midline of its front an odontoid, or tooth-like, process, formed by a confluence of the side ridges of the occlusal groove, in the top surface of the joint dentaries.
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Palaeontology 34(3):653-670 The dentary is noted as being of massive proportions, similar to the massive and robust dentaries found in Globidens and Prognathodon. A medially located shallow recess on the dentary indicates the groove for the splenial.
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Although the dentary bones assigned are nearly complete anteriorly, their morphology cannot confirm the entire depth or height of the lower jaw at the symphysis. This is because the dentary contributes only to the dorsal half of the symphysis in caseids, and the splenial most likely contributed to the symphysis, as it formed the lower part of the symphyseal region of the mandible. The assignment of these dentaries to Arisierpeton is based mainly on dental features, and to some extent on the labial surface characteristics of the bone. The teeth of these dentaries are identical to those found on the maxillae.
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In the rear jaws, the teeth are far apart. In top view, the symphysis of the lower jaw dentaries is four times longer than wide. The branches of the lower jaws are long and narrow, twenty times longer than wide in top view.
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Dryolestes holotype. Dryolestids are mostly represented by teeth, fragmented dentaries and parts of the rostrum. The Jurassic forms retained a coronoid and splenial, but the Cretaceous forms lack these. Another primitive feature is the presence of a Meckelian groove (Meridiolestidans lost it altogether).
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The postdentary bones are reduced to form a free standing coronoid process. The reflected lamina is spade shaped and does not extend below the dentary The area between left and right dentaries remains relatively long and narrow just posterior to symphyseal region.
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Hukoutherium is an extinct genus of mesonychid which lived during the middle Paleocene in Asia and was named by Chow. The genus became extinct during the Eocene Hukoutherium is known from a mandible with incisors, canines, and broken dentaries, a crushed crania and fragmentary bones.
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The lower jaw of Ufudocyclops is only partially known, and is only known from one of the referred specimens. Most of what is preserved consists of the front half of the mandibles, namely the two dentaries, as well as a splenial and portions of the angulars. The jaws are also missing the tip of the mandibular symphysis at the very front where the two jaw bones are fused, but enough is preserved to suggest the lower beak was somewhat squared off. The dentaries are toothless and covered in pits and grooves like those of the upper jaws, typical of the beaked lower jaws of derived dicynodonts.
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Skull at the University of Michigan An artist's rendering of Rodhocetus The holotype of R. kasrani, GSP-UM 3012 found in 1992, was described by : a cranium with two dentaries, most of the vertebral column as far as the anterior tail (C2–C7; T1–13; L1–6, S1–4, Ca1–4), most ribs, parts of the sternum, both hip bones, and a left femur. Gingerich et al. 1994 referred a specimen collected in 1981, GSP-UM 1852 two dentaries with teeth, to R. kasrani. Derived traits in R. kasrani, relative to older archaeocetes such as Pakicetus, includes high-crowned cheek teeth, larger auditory bullae, larger mandibular foramen, and mandibular canals.
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The angular shape of the rest of the skull is absent from the posterolateral section of the jaw. The dentaries near the symphysis are superficially asymmetrical. All known forms of Shantungosuchus also have a square-shaped fossa on the jugal, and a leaf-shaped palatine bone.
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The arrangement of the teeth meant that the front-most lower teeth would have had no corresponding upper tooth, and also that the two dentaries forming the lower jaw could not have been tightly fused. This characteristic would have been shared with its close relatives, the toothless hupehsuchians.
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In Chinese, translated by Will Downs, Bilby Research Center, Northern Arizona University, January, 2001. L. sexdentornis had in 1997 a torso longer than all other known Enantiornithes. It is slightly larger than Cuspirostrisornis, with a skull about 32 millimeters long. The paired dentaries and premaxillae each hold six teeth.
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There are two pairs of distinct foramina anterior and posterior to the dorsal transverse suture; modern placentals only bear one. It is about 1.9 centimeters long. The dentaries are short and robust, with a convex central border. The masseteric fossa is deep, and the canine is long and deep.
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In a 2017 study of niche partitioning in therizinosaurs through digital simulations, Lautenschlager found the dentaries of Segnosaurus experienced one of the lowest stress magnitudes during extrinsic feeding scenarios. Segnosaurus and Erlikosaurus were aided by the down-turned tip of the lower jaws and symphyseal regions, and probably also by beaks, which are known to mitigate stress and strain. By contrast, the straighter and more elongated dentaries of basal therizinosaurs—typical of their coelurosaurian ancestors—had the highest magnitudes of stress and strain. A downwards-pulling motion of the head while gripping vegetation was more likely than a sideways or upwards movement, though such behavior would be more likely in Segnosaurus and Erlikosaurus with their stress-mitigating jaws.
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In addition, the surface characteristics of the labial side of the dentaries are similar to those of the maxillae, showing little sculpturing, and occasional small foramina. A well-developed, anteriorly extending Meckelian canal is formed by the dentary bone, below which it would be attached to the splenial by sutures.
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By contrast, the straighter and more elongated dentaries of primitive therizinosaurs had the highest magnitudes of stress and strain. A downwards- pulling motion of the head while gripping vegetation was more likely than a sideways or upwards movement, though such behavior would be more likely in therizinosaurids with their stress-mitigating jaws.
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Oxlestes is currently a monotypic genus, containing a single species, O. grandis. Its specimens were recovered in the Cenomanian-aged Khodzhakul Formation of Uzbekistan. The holotype, CCMGE 6/11758, is composed of an axis vertebra, dentaries, canine teeth and a sagittal crest. The axis is relatively narrow, with a long, pointed anterior process.
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The dentary, the bone bearing the teeth, at the front curves sharply to the inside. This way both dentaries together had a profile fitting in the broad snout. The tooth row has a length of about . At the rear underside of the right lower jaw numerous ossicles, small bony scales, are visible.
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Such traits include the presence of a sagittal crest on parietal bone, maxillae and dentaries that are expanded from the middle to the sides, and with teeth present on both the occlusal and lingual surfaces. However, unlike rhynchosaurids, but like both Howesia and Mesosuchus, Eohyosaurus lacks a longitudinal occlusal groove and an occlusal blade on its maxillae and dentaries, respectively. Like in Rhynchosauridae and possibly Howesia (but not Mesosuchus), the occlusal margin of its maxilla is offset to the bottom from the lower margin of the main body of the jugal bone. Unlike rhynchosaurids that possess a short anguli oris crest on the jugal, in Eohyosaurus it is present on the side surface of the maxilla, while Mesosuchus lacks it entirely and it is unknown in Howesia.
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The type specimen (IVPP 84019) had its tenth and possibly eleventh neural spines fractured. They are fused together. A series of parallel ridges on one of the specimen's dentaries may represent tooth marks.Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.
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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.
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The fragmentary dentaries PIN 3360/1-3 were collected in the Vybor River locality, from the same formation. All specimens came from the Ustmylian Gorizont, dating to the early Olenekian faunal stage of the Early Triassic, about 249-247 million years ago. It was first named by I. V. Novikov in 1991 and the type species is Timanophon raridentatus.
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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.
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The specific descriptor deinosauriscus, "little dinosaur", alludes to the animal's small size for a dinosaur. The holotype, ZPAL MgD-II/29, was discovered in Late Cretaceous river sandstones of the Djadokhta Formation beds, dating from the late Campanian. It consists of an articulated but fragmentary skull and lower jaws comprehending paired maxillae, a partial jugal, palate bones and dentaries.
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Sophineta is known from holotype ZPAL RV/175, a nearly complete right maxilla. Many specimens are referred to the species and represent frontals, parietals, prefrontal, postfrontals, postorbitals, jugals, squamosals, pterygoids, quadrates, maxillae, premaxilla, dentaries, vertebrae and ilia. Skull fragments and vertebral column were associated. All specimens are housed in the Institute of Paleobiology, Polish Academy of Sciences, Warsaw.
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Each lower jaw dentary bears ten teeth. Where the dentaries touch each other, at the front of the lower jaws, they possess a common "chin", equalling a third of the front height. The horizontal groove in the inner side of the dentary, the fossa Meckeliana, largely opens to below. The anterior middle neck vertebrae are pierced by a foramen in the rear side.
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Jugulator is known primarily from isolated teeth and dentaries. The species is most distinctive in regards to its large size, being among the largest mammals in the region, some lower molars exceeding 5 mm in length and with an estimated body weight of about 750 g. The medial lower incisor is greatly enlarged, with a mitten- shaped crown that bears sharp cutting surfaces.
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The holotype USNM 392014, recovered in 1985 in a truck load of "marine marl" probably transported from New Bern, North Carolina, is two incomplete dentaries with a left P4 and broken M1-3; a right partial P4, partial M1-2, and a complete M3. The type locality is the Martin Marietta New Bern Quarry, Craven County, North Carolina (, paleocoordinates ).. Retrieved March 2013.
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The holotype specimen of Thanatotheristes degrootorum (TMP 2010.5.7) is based on a right maxilla, right jugal, right postorbital, right surangular, right quadrate, right laterosphenoid, left frontal, and both dentaries. The length of the skull has been approximated to be . It was smaller than the closely related Daspletosaurus, but the holotype individual was not osteologically mature at the time of death.
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The Mount Pulgnasco specimen represents an early rorqual that fed differently from modern species. Compared to the laterally bowed dentaries of the latter, its dentary is more straight, which should have made it impossible to perform the intermittent ram feeding seen in modern rorquals. Another primitive character is that the anterior border of the supraoccipital is triangular and pointed like in Miocene Cetotheriidae.
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Teeth were present only in the maxillae (upper cheeks) and dentaries (main bone of the lower jaw). The teeth were continually replaced, taking about half a year to form. They were composed of six types of tissues, rivaling the complexity of mammal teeth. They grew in columns, with an observed maximum of six in each, and the number of columns varied based on the animal's size.
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Also, there is evidence of bees, wasps, and termites in the Late Triassic, meaning that Desmatosuchus had access to insects that armadillos prey on. Their teeth are somewhat similar in shape, although armadillos have more peg-like teeth. Both Desmatosuchus and armadillos typically carry around 6 teeth on their dentaries. Both armadillos and Desmatosuchus have hypertrophied processes present on their limb bones, which indicates large limb muscles.
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Babiacetus was named by in an abstract based on the specimen's type (GSI 19647, left and right dentaries with cheek teeth). Gingerich and colleagues found a skull (GSP-UM 3005, much of a skull and lower jaws) while collecting a skeleton of a new species of Protosiren (Protosiren sattaensis) in the Drazinda Formation (, paleocoordinates ). Retrieved April 2013. in the Sulaiman Range of Punjab, Pakistan.
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The symphysis was often very thin tranversely and long, accounting for a considerable part of the jaw length, up to 60%. If a crest was present on the snout, the symphysis could feature a matching mandible crest, jutting out to below. Toothed species also bore teeth in their dentaries. The mandible opened and closed in a simple vertical or "orthal" up-and-down movement.
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A Megalosaurus rib figured in 1856 and 1884 publications by Sir Richard Owen is swollen at the point where it would have articulated with its vertebra. The Monolophosaurus jiangi specimen IVP 84019 had its 10th and possibly 11th neural spines fractured. The tenth neural spine is fused to the eleventh. A series of parallel ridges on one of the specimens' dentaries may represent tooth marks.
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Oxetocyon ("beginning dog") is an extinct monospecific genus of the Borophaginae subfamily of canids native to North America. It lived during the Early Oligocene epoch,PaleoBiology Database: Oxetocyon Taxonomy, Species existing for approximately . Fossils have been found in Nebraska and South Dakota. Fossils of Oxetocyon are rare and, as a result, the genus is poorly known, and only the teeth, dentaries, and a fragmentary skull have been reported.
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Dentaries AENM 2/846 (A-B) and AENM 2/902 (C-D). Kundurosaurus is a saurolophine diagnosed by four autapomorphies, unique derived traits. It has a prominent and thick ridge on the lateral side of the nasal that borders caudally the circumnasal depression and invades the caudal plate of the nasal. Its caudal buttress of the proximal head of the scapula is oriented quite laterally, parallel to the pseudoacromial process.
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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.
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In top view, the dentaries do not form the box-shaped snout seen in diplodocids, but are more rounded with a J-shaped curvature, as typical for dicraeosaurids. The front of the dentary had a hook-like "chin" projecting downwards, as seen in other flagellicaudatans. The angular bone of the hind part of the lower jaw was very elongated and longer than the surangular bone, unlike in diplodocids.
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Like the upper jaws, the paired lower jaws of pterosaurs were very elongated. In advanced forms, they tended to be shorter than the upper cranium because the jaw joint was in a more forward position. The front lower jaw bones, the dentaries or ossa dentalia, were at the tip tightly fused into a central symphysis. This made the lower jaws function as a single connected whole, the mandible.
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The only described material of A. laaroussii are dentaries, maxillae, a premaxilla and several teeth. They broadly resemble A. madagaskarensis in general form but with a few distinguishing differences. The tooth count of A. laaroussii is higher, with 15–16 teeth in the maxilla compared to the 11–13 of A. madagaskarensis. The teeth of A. laaroussii are also taller than those of A. madagaskarensis and have more closely packed denticles.
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Reconstruction of Taniwhasaurus. In general, tylosaurines were large-bodied marine lizards armed with sturdy, conical teeth and an elongated premaxilla and extensions of the dentaries that do not bear teeth to the very end such as is found in other genera of mosasaurs. Cope's original concept of a "battering ram" snout is not supported by fossil evidence. Stomach contents from a tylosaur recovered in South DakotaMartin JE, Bjork PR. 1987.
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This extension was supplied by neurovascular foramina (small pits) found on the lateral surfaces. The known specimens of the therizinosaurids Erlikosaurus, Neimongosaurus and Segnosaurus preserve numerous neurovascular foramina (more notorious on Erlikosaurus), indicating that a well-developed beak was present in life. Both maxilla and premaxilla were toothed and some species of therizinosaurids had specialized, recurved dentaries such as Segnosaurus and possibly Neimongosaurus. Braincases are known from three therizinosaurids: Erlikosaurus, Neimongosaurus and N. mckinleyi.
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The remains of Parasuminia currently consist only of fragmented, disarticulated pieces of skull as well as isolated pairs of dentaries that remain held together by strong suturing at the jaw tips. The generic name is from the Latin "para" ("close", "similar") and the genus Suminia for its close resemblance and relationship to the latter. The specific name is in memory of the palaeontologist M.F. Ivakhnenko and in recognition of his "outstanding" work on Russian palaeontology.
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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.
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The holotype of the species, BNMH R. 332, had been found in a layer, the "freestone", of the Upper Inferior Oolite dating from the late Bajocian, about 168 million years old. It consists of skull and lower jaw parts. It contains both premaxillae, a right maxilla, a possible vomer, both dentaries and a right surangular. Most of the material is present in a main block; a second block had been separated, longitudinally splitting the maxilla.
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The tooth margin alternates between concave and convex on the dentary. 19 teeth are in the dentaries, but there may be more that are not visible due to presence of the matrix it was mostly uncovered from. The eight caniniform teeth are procumbent, or tilt forward, and smooth but are striated near where they attach to the jaw. The skull was not prepared in such a way that allows for examination of the palate.
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Finally, in 2020, Gregory Funston gave it a genus of its own, Citipes; the name is a Latin word meaning "fleet-footed". The holotype is a tarsometatarsus. A pair of associated ilia and a sacral vertebra have been referred, as have a pair of fused dentaries, a tibia, and several isolated metatarsals. Osteohistological analysis shows that it was smaller than contemporary caenagnathids, and it is distinguished by fusion of the foot bones.
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Juvenile remains are known from several locations, mostly based on teeth. Thescelosaurus was a heavily built bipedal animal, probably herbivorous, but potentially not. There was a prominent ridge along the length of both maxillae (the tooth-bearing "cheek" bones), and a ridge on both dentaries (tooth- bearing bone of the lower jaw). The ridges and position of the teeth, deeply internal to the outside surface of the skull, are interpreted as evidence for muscular cheeks.
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It is uncertain how many teeth Elasmosaurus had, due to the fragmentary state of the fossils. It probably had six teeth in each premaxilla, and the teeth preserved there were formed like large fangs. The number of premaxillary teeth distinguished Elasmosaurus from primitive plesiosauroids and most other elasmosaurids, which usually had fewer. The two teeth at the front were smaller than the succeeding ones, and were located between the first two teeth in the dentaries of the lower jaws.
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Lycophocyon is an extinct genus of caniformian carnivoran from Middle Eocene (early Duchesnean and possibly late Uintan NALMA) deposits of San Diego County, California. Lycophocyon is known from the holotype UCMP 85202, a partial left and right dentary. Paratypes include UCMP 170713, SDSNH 107658, SDSNH 107659, SDSNH 107442, SDSNH 107443 and SDSNH 107444, partial dentaries, mandibles and other cranial remains, and SDSNH 107446 and SDSNH 107447, cranial and postcranial fragments. Many additional specimens are also known.
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The lesser bite force for Erlikosaurus better served in stripping and cropping leaves, rather than active mastication. On a newer study with more therizinosaur taxa, Lautenschlager found similar conclusions. The evolutionary trends in jaw mechanics of therizinosaurs noticed a change in bite force through time, from higher bite forces in early members to lesser ones in the advanced therizinosaurids. Therizinosaurids were aided by the down-turned tip and symphyseal regions (union between bones) of the dentaries, and probably also by beaks.
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Mythunga is known from a partial skull, holotype QM F18896 found in April 1991 by Philip Gilmore in marine rocks of the late Albian-age Toolebuc Formation at Dunluce Station west of Hughenden, Queensland. Only the middle snout and corresponding parts of the lower jaws are known, including the rear of a left premaxilla, the lower parts of both maxillae, the rear dentaries and a right splenial. They were three-dimensionally preserved, associated in a chalk nodule. It represents a subadult individual.
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E. platyops skull Unlike the sea turtles Toxochelys and Eochelone, Euclastes has a secondary palate. However, the secondary palate of Euclastes is not as extensive as it is in Ctenochelys and Angolachelys. The genus can be distinguished by later sea turtles based on its broad, low skull; broad, flat palate; wide, flat dentary bone with an elongated symphysis; and low tomial ridge on the beak. The widened palate and dentaries give Eochelone wide, flat jaws suitable for crushing hard-shelled organisms.
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63136, one of the most complete dentaries found for any silesaurid. As in other sulcimentisaurians, the meckelian groove is positioned close to the lower edge of the jaw and the teeth are constricted at the root. The front tip of the dentary is pointed, toothless, and has a lateral groove akin to that of Silesaurus and Sacisaurus, along with several medial grooves. Further back, the dentary is relatively deep and develops a lateral ridge similar to one reported for Diodorus and Eucoelophysis.
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Teeth of Kwanasaurus have been found both as isolated material and within maxillae and dentaries. Isolated teeth are leaf-shaped, with coarse denticles, slightly flattened sides, and crown tips more than halfway towards the rear of the tooth. The lingual (tongue) side of the tooth has a thick vertical ridge covered in striations. Sacisaurus, Eucoelophysis, and possibly Technosaurus are the only other silesaurids known to possess similar teeth, although leaf-shaped teeth are also common in various other herbivorous archosaurs.
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Restoration of Aegyptocetus and a shark Aegyptocetus had features in its cranium and dentaries adapted for hearing in water. Its thoracic vertebrae (T1–T8), however, had long neural spines which is a characteristic of the weight-bearing system of land-living mammals retained in protocetids, such as Rodhocetus and Qaisracetus, but absent in the more derived basilosaurids, such as Dorudon. This suggests that Aegyptocetus, like other protocetids, was able to support its body on land and probably was semi-aquatic.
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The spinal column was largely articulated, the remainder consisted of disarticulated bones. Parts of the skeleton had been exposed on the desert surface and had suffered erosion damage. Additionally, several specimens have been assigned as paratypes: MNN GDF 501 to 508 include a snout, a quadrate from the back of the skull, three dentaries (tooth-bearing bones of the lower jaw), an axis (second neck vertebra), a rear cervical vertebra, and a rear dorsal vertebra. MNN GDF 510 to MNN GDF 511 comprise two caudal vertebrae.
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Franchaius from the early Eocene of Europe, Benaius, Lofochaius, Meiostylodon, and Huananius from the early Paleocene of China, and Yuesthonyx from the late Paleocene of China are primitive forms. Interogale from the late Paleocene of China, and Anchilestes probably from the middle Paleocene of China, were once assigned to Anagalida, but may also be primitive tillodonts. The monophyly of the subfamily Trogosinae is unchallenged, but Esthonychines most likely includes the ancestors of Trogosinae and therefore is probably paraphyletic. Tillodontia is mostly known from dentaries and teeth.
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Faunal assemblages from the upper Horseshoe Canyon Formation, an early Maastrichtian cool-climate assemblage from Alberta, with special reference to the Albertosaurus sarcophagus bonebed This article is one of a series of papers published in this Special Issue on the theme Albertosaurus. Canadian Journal of Earth Sciences, 47(9), 1159-1181. which dates to about 68.5 million years ago. The only known specimen consists of parts of the upper and lower jaws—both premaxillae, a right maxilla, both dentaries—teeth and numerous small fragments.
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Stenaulorhynchus shares characteristics with other early rhynchosaurs, including their ankylothecodont dentition (teeth within deep sockets and fused to the bone) and precision-shear bite. They also have double-bladed dentaries and grooves on the upper surface of the maxilla. One of the differences between them is that Stenaulorhynchus had smaller maxillary teeth with a larger gap between the tooth rows. Stenaulorhynchus is differentiated from the later Hyperadapedon by its more lateral eyes, more forward braincase, and longer lower jaw with the teeth located more anteriorly.
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The type species is S. venezuelensis. Like other gavialoids, Siquisiquesuchus had a long, narrow rostrum on its skull, accounting for approximately 60% of the skull's length. The number of teeth in the premaxillary bones at the tip of the snout is not known, but the maxillae making up most of the rostrum had at least 20 teeth each, and the dentaries of the lower jaws had at least 23. Some details of the described skulls cannot be determined because the sutures are not visible.
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All other silesaurid maxillae recovered from the area seem to represent the same taxon, indicating that Kwanasaurus was likely the only silesaurid from the Eagle Basin. With this in mind, all other Eagle Basin fossils resembling those of silesaurids have been referred to the taxon. These include multiple dentaries, teeth, ilia, femora, and a humerus. Dinosauromorph-like tibia and scapulae from the area may also belong to Kwanasaurus, though they have not been referred to the genus due to lacking any clear silesaurid features.
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Heishanobaatar is an extinct genus of eobaatarid multituberculate which existed in Shahai and Fuxin formations, northeastern China, during the early Cretaceous (Aptian/Albian age). It was first named by Nao Kusuhashi, Yaoming Hu, Yuanqing Wang, Takeshi Setoguchi and Hiroshige Marsuoka in 2010 and the type species is Heishanobaatar triangulus. Known from dentaries, lower incisors, and premolars, Heishanobaatar is distinguished by its laterally triangular third premolar, from which its species name is derived. Its referral to Eobaataridae was considered questionable by Kusuhashi et al 2019.
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Galadi is an extinct genus of predatory bandicoot from Oligo-Miocene deposits of Riversleigh, northwestern Queensland, Australia. It was first named by K.J. Travouillon, Y. Gurovich, R.M.D. Beck and J. Muirhead in 2010 and the type species is Galadi speciosus; additional three species, G. adversus, G. amplus and G. grandis, were described in 2013. The genus is represented by three well-preserved skulls and several isolated maxillae and dentaries. Its body mass would have been close to two pounds, making it relatively large for its family.
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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.
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The authors reported that the cervical of the holotype specimen was completely prepared out of the matrix along with the scapulacoracoid, a sacrum, and part of a mandible. The study of the glenoid indicated that it had a pterosaur saddle-shaped articulation for the humerus. In addition, the authors reported a parallel alignment of the dentaries, indicating that they formed a mandibular symphysis. Czerkas & Ford interpreted the presence of the elongate mandibular symphysis and spoon-like expansion of the anterior end of the jaws as aligning Utahdactylus with pterodactyloids, and specifically within Ctenochasmatidae.
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The most common remains of young hadrosaurs in the Dinosaur Park Formation are dentaries, bones from limbs and feet, as well as vertebral centra. The material showed little or none of the abrasion that would have resulted from transport, meaning the fossils were buried near their point of origin. Bonebeds 23, 28, 47, and 50 are productive sources of young hadrosaur remains in the formation, especially bonebed 50. The bones of juvenile hadrosaurs and fossil eggshell fragments are not known to have preserved in association with each other, despite both being present in the formation.
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Teeth were present only in the maxillae (upper cheeks) and dentaries (main bone of the lower jaw). They grew in columns, with an observed maximum of six in each, and the number of columns varied based on the animal's size. There were 51 to 53 columns per maxilla and 48 to 49 per dentary (teeth of the upper jaw being slightly narrower than those in the lower jaw). Life restoration E. regalis had thirteen neck vertebrae, eighteen back vertebrae, nine hip vertebrae, and an unknown number of tail vertebrae.
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"Purgatorius, plesiadapiforms, and evolution of Hunter–Schreger bands." J. Vertebr. Paleontol 11 (1991). Cited by Due to the fragmentary dentaries found in the Garbani Channel fauna from Purgatorius janisae the morphology of the canine and incisor alveoli suggest the derived gradient in the crown size of: I1>or = I2>I3 A phylogenetic analysis of 177 mammal taxa (mostly Cretaceous and Palaeocene fossils), published in 2015, suggests that Purgatorius may not be closely related to primates at all, but instead falls outside crown-group placentals - specifically as the sister taxon to Protungulatum.
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Barbaturex is an extinct genus of giant herbivorous iguanian lizards from the Eocene of Myanmar. It is represented by a single species, Barbaturex morrisoni, which is known from several partial dentaries (lower jaw bones) and a fused pair of frontals, two bones that form part of the top of the skull. Based on the size of these bones, Barbaturex morrisoni is estimated to have been about from snout to vent, and possibly up to including the tail. Barbaturex morrisoni was named after The Doors frontman Jim Morrison, a play on his epithet "The Lizard King".
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The known teeth of the front part of the lower jaw were large fangs, and the teeth at the back of the jaws appear to have been smaller. The dentition of elasmosaurids was generally heterodont (irregular throughout the jaws), with the teeth becoming progressively smaller from front to back. The maxillae (largest tooth bearing bone of the upper jaw) of elasmosaurids usually contained 14teeth, whereas the dentaries (the main part of the lower jaws) usually contained 17 to 19. The teeth interlocked, and their tooth crowns were slender and rounded in cross-section.
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Colosteids were unique compared to most stegocephalians in the fact that a pair of palatal fangs were present on the premaxillary bones at the tip of the snout. In conjunction with the forward position of these fangs, the dentary bones of the lower jaw developed a notch on either side near the symphysis (chin). The symphysis itself is formed by a rough area of bone on the left and right dentaries. This rough patch is formed by a complex system of ridges, which have been described as "brassicate" (textured like a cauliflower).
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Icaronycteris is an extinct genus of microchiropteran (echolocating) bat that lived in the early Eocene, approximately , making it the earliest known definitive bat. Four exceptionally preserved specimens, among the best preserved bat fossils, are known from the Green River Formation of North America. There is only one thoroughly described species of bat in the genus, I. index, although fragmentary material from France has also been tentatively placed within Icaronycteris as the second species I. menui. I. sigei is based on well-preserved fragments of dentaries and lower teeth found in Western India.
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One autapomorphy (unique trait) was used to diagnose the taxon as a new species: a very elongated edentulous section on the dentary, which was medially (inwardly) extended. No teeth were preserved, but there are 35 tooth positions. Several other European hadrosaur dentaries were compared based on published data, and the specimen was found to be unique compared to all of them. Though the specimen proved too fragmentary to be used for phylogenetic analysis, it was determined to be a hadrosaurid of some kind, more derived than Pararhabdodon, considered the sister taxon to Hadrosauridae.
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Material from these quarries was described in 2012 by Kirkland along with Andrew McDonald, John Bird, and Peter Dodson, who also provided an updated diagnosis for Eolambia based on this material. One specimen discovered at the Cifelli #2 quarry, a right dentary catalogued as CEUM 34447, is unusual compared to other Eolambia specimens, including both adults and juveniles. While the ratio between the mid-point depth and overall length of the dentaries in other individuals generally ranges from 0.19 to 0.24, the same value in CEUM 34447 is 0.31, making it unusually deep.
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The dentary also does not deepen substantially at the front end, and thus lacks one of the distinguishing traits of Eolambia dentaries. However, the other distinguishing trait, which is the expansion of the front end of the coronoid process, is present in the specimen. Although it is possible that this individual represents an unusual Eolambia specimen, McDonald and colleagues cautioned that it may represent a distinct hadrosauroid that differs in the morphology of the dentary from Eolambia (albeit one that is not suggested by any of the other materials at the quarry).
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Stong jaw musculature combined with a relatively short and tall dentary would have resulted in a very powerful bite. The skull of the type specimen of Prognathodon saturator is nearly complete, only lacking the anterior portion of the premaxilla and the dentaries. Though most of the anterior marginal teeth are missing, the inclination of the preserved roots suggest that P. saturator had procumbent teeth, a trait also seen in P. solvayi. The dorsal margin of the dentary is concave, whilst the ventral margin of the maxilla is slightly convex.
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Compared to other adapiform primates, the fossil record of Sivaladapis is limited, lacking any cranial or postcranial fossil material. The genus is known exclusively from isolated fossil teeth and partial dentaries and maxillae recovered from the Chinji Formation (Siwalik Group) of India and Pakistan. Both S. nagrii and S. palaeindicus are considered a fairly large adapiforms, with body-size estimates ranging from 2.6 to 3.4 kilograms. The prominent and well-developed shearing crests on its molars and premolars suggests the genus was adapted to a predominately folivorous diet, subsisting on fibrous leaves.
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The external nares were long, narrow and horizontally positioned; the same was true of the larger antorbital fenestrae, a pair of bony openings in front of the eyes. The rear of the skull is poorly known but for a short quadrate bone, which had broad condyles (round protrusions) away from the centre of attachment and—like in the spinosaurid Baryonyx—had a large foramen (opening) separating it from the quadratojugal bone. The lower jaws were greatly elongated and narrow, forming a rigid structure as their dentaries touched each other at the midline, reinforcing the mandible against torsional (bending and twisting) forces.
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On the labial (outer) surface of the dentary, there is one large mental foramen (opening). The mandibular symphysis, where the two halves of the lower jaw meet, is poorly preserved, but there is nothing to suggest that the left and right dentaries were fused. The lower margin of the bone is convex at the front, but concave further back, so that the depth of the dentary is 8.3 mm (0.33 in) below the diastema, but only 7.0 mm (0.28 in) below the third cheektooth. The origin of the coronoid process, a projection at the back of the dentary, lies far to the front.
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Its perinarial fossa was a common characteristic among mesoeucrocodylians, and it also lacked a notch in the upper jaw to receive an enlarged lower caniniform tooth; both characteristics were likely plesiomorphic for the group Notosuchia. Razanandrongobe had forward-facing bony nostrils like sphagesaurids (Caipirasuchus shown) In Razanandrongobe, the incisive foramen was larger than most mesoeucrocodylians, while the robust palate on the maxilla was more typical. The upturning of the dentary was most like Baurusuchidae and Kaprosuchus, but Uruguaysuchus and Peirosauridae also had dentaries that tapered upwards in an arch. Unlike Uruguaysuchus, the tooth sockets were not fused.
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The remains of Ekrixinatosaurus helped fill in more information about abelisaur anatomy as it contained portions of the skeleton that were previously unknown, unpublished, or poorly preserved in other specimens. The holotype skeleton (MUCPv-294) was well preserved yet disarticulated. It contained elements including a left and partial right maxillae; basicranium; both dentaries; teeth; cervical, a dorsal, sacral and caudal vertebrae; haemal arches; ribs; ilia, pubis and proximal ischia; left and distal end of right femur; left tibia; left astragalus and calcaneum; proximal end of left fibula and right tibia; metatarsals; phalanges; and a pedal ungual.
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On the contrary, the latter has very symmetrical teeth with moderate denticles. The respective indistinct and specialized dentition of Erlikosaurus and Segnosaurus indicates that these two therizinosaurids were separated by niche differentiation in food acquisition, processing, or resources. This conclusion is strengthened by the large difference in estimated body masses, which is up to 500%. Life restoration of the larger and sympatric Segnosaurus In a 2017 study of niche partitioning in therizinosaurs through digital simulations, Lautenschlager found the straighter and more elongated dentaries of primitive therizinosaurs had the highest magnitudes of stress and strain during extrinsic feeding scenarios.
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All of the teeth were either completely flattened or weakly pointed, and many of the teeth bore a constriction between the root and the crown. Unlike other ichthyosauriforms with molariform teeth, all of the tooth crowns were "swollen" to a similar extent. On the maxilla (upper jawbone) and dentary (lower jawbone), the teeth were arranged in three rows, with the outermost row having the most and largest teeth; the maxillae had seven, five, and probably one teeth each, while the dentaries had ten, seven, and four teeth each. Among ichthyosauriforms, only Cartorhynchus and Xinminosaurus have multiple rows of teeth.
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The surface of the maxilla is profusely sculpted with ridges and grooves, a feature that clearly distinguishes it from Iberosuchus. The lower jaws are mostly only known from incomplete dentaries (as well as part of the splenial), and their surfaces are as similarly strongly sculpted as the upper jaws. The teeth are relatively narrow and serrated (ziphodont), similar to those of predatory theropod dinosaurs and unlike the conical teeth of modern crocodylians. Few teeth themselves are preserved, but they include a very large and prominent serrated 'pseudocanine' that fits into the notch of the upper jaw.
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The unusually high amount of teeth present in the dentaries of both species of Pluridens initially made it difficult to immediately assign a classification on the subfamily level. Lingham-Soliar (1998) remarked that the unique combination of features (e.g. the high tooth count and a unique tooth shape) would normally result in the creation of a completely new subfamily, but did not create a new subfamily due to the rather fragmentary nature of the remains. Lindgren and Siverson (2005) considered many of the unique features of Pluridens to be shared with Halisaurus and reassigned P. walkeri as "Halisaurus walkeri".
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The most common remains of young hadrosaurs in the Dinosaur Park Formation are dentaries, bones from limbs and feet, as well as vertebral centra. The material showed little or none of the abrasion that would have resulted from transport, meaning the fossils were buried near their point of origin. Bonebeds 23, 28, 47, and 50 are productive sources of young hadrosaur remains in the formation, especially bonebed 50. The bones of juvenile hadrosaurs and fossil eggshell fragments are not known to have been preserved in association with each other, despite both being present in the formation.
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After being initially named as a lizard, Polydontosaurus was reclassified as a troodontid, a classification which stands today. Since 1969 Polyodontosaurus has been considered a synonym of Stenonychosaurus, and later its senior synonym Troodon. Polyodontosaurus is potentially a synonym of the taxon Latenivenatrix, named in 2017, but they may come from separate regions of the formation. Van der Reest & Currie in 2017 determined that due to the lack of sufficient material in the holotype, and that the dentaries of troodontids to not bear unique, autapomorphic features, Polyodontosaurus was a nomen dubium, and could not be considered senior synonym of Latenivenatrix.
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Each side of the tip of the upper jaw had four teeth, while the maxillae (main tooth-bearing bone of the upper jaw) and dentaries (tooth- bearing bone of the lower jaw) had twelve or thirteen each. The thigh bones were slender, and there were bony scutes on both the back and belly. The scutes on the upper surface were arranged in two rows running the length of the animal. Clark and Sues performed a phylogenetic analysis and found Kayentasuchus to have an unresolved position along with several other sphenosuchians, neither closer to true crocodiles or to Sphenosuchus.
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The specific name honours Mona Shahin, one of the founders of the Mansoura University Vertebrate Paleontology Center. The Mansourasaurus specimen described in 2018 is its holotype, MUVP 200, discovered in a layer of the Quseir Formation dating from the late Campanian, about seventy-three million years old. It consists of a partial skeleton with skull and lower jaws. It contains a fragment of the skull roof, a part of the lower braincase, the dentaries of the lower jaws, three neck vertebrae, two back vertebrae, eight ribs, the right scapula, the right coracoid, both humeri, a radius, a third metacarpal, three metatarsals, and parts of osteoderms.
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Their powerful incisors, with limited bands of enamel, would have been well adapted to gnawing and to cutting hard seeds (similar to rodents). Since it was larger than some other multituberculates, Catopsbaatar would have to open its mouth only 25 degrees to crush hard seeds in diameter; a 40-degree gape would have caused dislocation. After the incisors cut, the premolars and molars would begin to grind with a "power stroke". Multiple views of the dentaries of two specimens According to Gambaryan and Kielan-Jaworowska, the adaptation for crushing hard seeds sometimes—as in Catopsbaatar—opposed the benefit of a low condylar process (which discourages mandibular dislocation).
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Oedaleops was first described by paleontologist Wann Langston Jr. in 1965 on the basis of a mostly complete skull (specimen UCMP 35758, the holotype of Oedaleops) and a few isolated skull and postcranial fragments. The UCMP 35758 skull has been the sole specimen of Oedaleops used in most analyses of its evolutionary relationships. The more fragmentary specimens have been assigned to Oedaleops with caution because they are hard to distinguish from the bones of other Cutler Formation synapsids such as Aerosaurus. Additional specimens of Oedaleops were described in 2013, including many isolated dentaries (lower jaw bones), pectoral and limb bones, and disarticulated vertebrae representing at least three new individuals.
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Pyrenasaurus is an extinct genus of lizard that includes only one species, the type species Pyrenasaurus evansae, which lived around the Pyrenees mountains during the Late Eocene. P. evansae was named in 2014 on the basis of three dentaries (bones that form the lower jaw), one from the Phosphorites du Quercy in Quercy, France and two from the Sossís fossil locality in Catalonia, Spain. The paucity of known material makes its relationships uncertain; it is either a true skink in the family Scincidae or a close relative of skinks in the larger group Scincoidea. Pyrenasaurus is very small for a lizard, with a dentary length of only .
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This was made the separate genus Metriacanthosaurus in 1964. The second was Megalosaurus nethercombensis, named after its provenance from Nethercombe and based on two dentaries, leg bones, a pelvis and vertebrae from the Middle Jurassic, which von Huene himself in 1932 made the separate genus Magnosaurus. In 1925, Depéret, based on two teeth from Algeria, named Megalosaurus saharicus. In 1931/1932 this was made the separate genus Carcharodontosaurus. In 1956 von Huene by mistake named the same species as Megalosaurus africanus, intending to base it on remains from Morocco but referring the Algerian teeth; this implies that M. africanus is a junior objective synonym of M. saharicus.
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Eosimops had indistinguishably fused premaxillae, with the single element forming the anterior portion of the snout and alveolar margin along with the anterior edge of the external nares. The premaxilla forms part of the secondary pallet, and bears two sets of paired anterior ridges as well as a single median posterior palatal ridge. A dorsally directed portion of the premaxilla with a rounded edge projects between the nasals, diagnostic of dicynodonts thanks to the narrow groove along its midline. The left and right dentaries of Eosimops’ mandible were fused, and the anterior surface sported a vascular foramina which was likely associated with a keratinaceous beak.
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Coelodontognathus is an extinct genus of reptile from the Early Triassic (late Olenekian stage) of European Russia. It was originally described as a procolophonid parareptile in 1967 but was reclassified as a possible trilophosaurid archosauromorph in 2008. The genus includes two species: the type species C. donensis and C. ricovi. C. donensis is known from the holotype PIN 4173/129 (SGU 104/3103) and the referred PIN 4173/130 (SGU 104/3104), and C. ricovi is known from the holotype PIN 4173/127 (SGU 104/3101) and the referred PIN 4173/128 (SGU 104/3102), all of which represent dentaries that are housed at the Paleontological Institute, Russian Academy of Sciences.
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Miodentosaurus is a thalattosaur, a group of marine reptiles with long, paddle-like tails and short legs with independently movable digits. Miodentosaurus is specifically an Askeptosauroid, a specific group of thalattosaurs with rather straight snouts. Despite being closely related to Askeptosaurus (a thalattosaur with a very long and toothy snout), Miodentosaurus had a quite short snout (shorter than the rest of the head) with only a few conical teeth on the premaxillae and dentaries. Although this snout configuration is not known in any other thalattosaurians, Miodentosaurus does share a number of other features with Askeptosauroids, such as having 10 neck vertebrae and a large pineal foramen.
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The platypus has an average body temperature of about rather than the typical of placental mammals. Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes. Modern platypus young have three teeth in each of the maxillae (one premolar and two molars) and dentaries (three molars), which they lose before or just after leaving the breeding burrow; adults have heavily keratinised pads in their place. The first upper and third lower cheek teeth of platypus nestlings are small, each having one principal cusp, while the other teeth have two main cusps.
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Vitalia is an extinct genus of reptile from the Early Triassic (late Olenekian stage) of European Russia known from the type species V. grata. It is known from the holotype dentary PIN 4173/126 (SGU 104/3105) as well as two additional dentaries PIN 1043/627 and 1043/628, all housed at the Paleontological Institute, Russian Academy of Sciences. The type dentary was originally included in the hypodigm of Coelodontognathus donensis named by the notable Russian vertebrate paleontologist Vitaliy Georgiyevich Ochev in 1967. Ivakhnenko (1973) separated the specimen and gave it its own genus and species name in light of the new material, which he named in honor of Ochev.
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The dentaries of Vitalia were collected at the Donskaya Luka Locality near the village of Sirotinskaya in Ilovlinsky District, Volgograd Oblast, from the Lipovskaya Formation of the Gamskii Horizon. Like Coelodontognathus, Vitalia was originally described as a procolophonid parareptile in 1973, but Arkhangelskii & Sennikov (2008) reclassified the taxon as a possible trilophosaurid archosauromorph. Vitalia is thought to be similar to the possible trilophosaurids Coelodontognathus and Doniceps, both of which are known exclusively from the same locality. Coelodontognathus and Vitalia are similar to procolophonids in that they have wide teeth but differs from them in that they have tooth roots set deep into the jaws.
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Also like other early archosauromorphs, Azendohsaurus has a small (3–5 mm across) parietal foramen ("third eye") on the roof of the skull. pterygoid, showing the numerous rows palatal teeth The lower jaw is especially convergent with those of sauropodomorphs, with an articular joint where the jaw hinges positioned below the level of the tooth row and downward curving dentaries, as well as the similarly shaped teeth. These features are variously found in other herbivorous Triassic archosauromorphs, but this combination is only known in Azendohsaurus and sauropodomorphs. The teeth are all roughly leaf- shaped (lancoelate) with expanded crowns and bulbous bases that are fused to the jaw bones (ankylothecodont).
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Due to their mouth posted far back from the front end of their body, "this places the mouth in a superior position making the garfish 'well adapted 'for surface feeding" (Montgomery & Saunders, 1984). Another feature they obtain is the two to three rows of teeth that they have in both the upper and lower jaw (Montgomery & Saunders, 1984). These type of teeth are called tricuspid, there are teeth are on both the premaxillae (which is small cranial bones at the very tip of the upper jaw(Berkovitz & Shellis, 2017) and the dentaries (which is an anterior bone of the lower jaw which is an area that bears teeth(Borgen & Nakrem, 2016).
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Maiaspondylus is known from the holotype UALVP 45635, a disarticulated but nearly complete skeleton preserved in three dimensions and from the referred materials UALVP 45639, two articulated, partially preserved embryos and eight articulated vertebrae of an adult, UALVP 45640, 14 articulated vertebrae of a juvenile, UALVP 45640, 12 articulated vertebrae, UALVP 45642, a partial snout and left dentaries with teeth and UALVP 45643, a fragmentary snout. All specimens were collected at Hay River from the Loon River Formation, dating to the early Albian stage of the Early Cretaceous, about 110 million years ago. All Maiaspondylus specimens were originally referred to Platypterygius. However, all recent cladistic analyses found that Maiaspondylus is a valid genus of ophthalmosaurid.
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The holotype, AODF 876, was found in a layer of the Winton Formation dating from the Cenomanian - lower Turonian, about ninety-six million years old. It consists of a partial skeleton with skull and lower jaws. It contains the front part of the head with the premaxillae, the maxillae and the dentaries; the left frontal bone, the rear part of the left lower jaw; forty single teeth; five neck vertebrae; the right shoulder joint; the left ulna; the left radius; the proximal and distal left wrist bones; two fourth metacarpals; phalanges from the first to third fingers of the left hand; and the first phalanx of the fourth finger. It represents a fully-grown but not yet mature animal.
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Humpback skeleton showing the flexible "slingshot" symphysis present in baleen whales Solitary mammalian carnivores that rely on a powerful canine bite to subdue their prey have a strong mandibular symphysis, while pack hunters delivering shallow bites have a weaker one. When filter feeding, the baleen whales, of the suborder Mysticeti, can dynamically expand their oral cavity in order to accommodate enormous volumes of sea water. This is made possible thanks to its mandibular skull joints, especially the elastic mandibular symphysis which permits both dentaries to be rotated independently in two planes. This flexible jaw, which made the titanic body sizes of baleen whales possible, is not present in early whales and most likely evolved within Mysticeti.
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As far as can be determined, all of the dentary teeth conform to this pattern, although one tooth at tooth position 8 in GAA 00246-1, although slightly damaged at the tip, does appear to have both anterior and posterior cusps. In all cases the teeth are more slender than in the dentaries of Oromycter and have more modest lingual shoulders at the base of the crown. Overall, it appears that the dentition in Arisierpeton shows some modifications in tooth shape and crown outline from the primitive amniote condition seen in the basal caseid Eocasea and in eothyridid caseasaurians. The teeth show little or no recurvature, but instead have some medial or lingual curvature apically.
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There were five teeth in both of the bones that made up the tip of the snout (premaxilla), fifteen in the paired maxillae that formed the sides of the upper jaw, and twenty in both dentaries of the lower jaw. The front of the lower jaw had a flattened shape, and the teeth located here pointed partially forward, with a spade-like form. The teeth had variable shapes; the first thirteen teeth in the lower jaw were pointed, while the last seven graded from a spatulate shape to a large globular shape. Aside from the horns, the skull and particularly the lower jaw of Ceratosuchus were very similar to that of its contemporary Allognathosuchus.
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3D reconstruction of the dentaries and maxilla as they would have articulated in life, in multiple views Motani and colleagues hypothesized in 2014 that Cartorhynchus was a suction feeder which fed by concentrating pressure in its narrow snout. This was further supported by the robustness of its hyoid and hyobranchial element (which would have anchored the tongue), and their incorrect observation of toothlessness. Similar inferences were subsequently made for Sclerocormus. Shastasaurus and Shonisaurus had previously been interpreted as suction-feeding ichthyosaurs, but a quantitative analysis of Triassic and Jurassic ichthyosaurs by Motani and colleagues in 2013 showed that none of them had sufficiently robust hyobranchial bones nor sufficiently narrow snouts to enable suction feeding.
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Ancalecetus (from Greek ankale, "bent arm", and ketos, "whale") is an extinct genus of early whale known from the Late Eocene (Priabonian, ) Birket Qarun Formation (, paleocoordinates ) in Wadi Al-Hitan, Egypt.. Retrieved July 2013.. Retrieved July 2013. The species is named after anthropologist and primate researcher Elwyn L. Simons who discovered the type specimen in 1985. The holotype is a partial cranium (the top of the skull was destroyed by erosion), both dentaries, 20 vertebrae and some sternal elements, partial ribs, and most of both forelimbs. Ancalecetus differs from other archaeocetes and modern whales in having narrow scapulae, very limited mobility in the shoulder joint, and fusion of the humerus, ulna, and radius at the elbow joint.
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The hadrosaurs and ceratopsians of the Cretaceous Period, as well as many herbivorous mammals, would convergently evolve somewhat analogous dental batteries. As opposed to hadrosaurs, which had hundreds of teeth constantly being replaced, tooth replacement in heterodontosaurids occurred far more slowly and several specimens have been found without a single replacement tooth in waiting. Characteristically, heterodontosaurids lacked the small openings (foramina) on the inside of the jaw bones which are thought to have aided in tooth development in most other ornithischians. Heterodontosaurids also boasted a unique spheroidal joint between the dentaries and the predentary, allowing the lower jaws to rotate outwards as the mouth was closed, grinding the cheek teeth against each other.
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The three feet long head and its dentaries had no signs of either teeth nor tooth sockets. Cortesi noted that at that time few naturalists could assign cetacean fossils to individual species, and he therefore never named his specimen. thought the "Baleine de Cortesi" represented a distinctive species because it was a very small adult individual and because the curvature of the maxillary branches was less convex than in any other known whale. Other French naturalists; named it "Le rorqual de Cortési"; arguing that both Cortesi's fossil whales ("rorqual de Cortési" and "de Cuvier") were closely related to extant rorquals and the only difference between them was the much smaller size of the former.
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Tethysaurus is the type genus, as it is the best-represented genus of the subfamily, known from multiple partial skeletons. Thus the subfamily name derives from the name of its type genus. Pannoniasaurus is known from various material, including 2 isolated premaxillae, 3 maxillae, 2 postorbitofrontals, 2 quadrates, 3 dentaries, 3 splenials, 3 angulars, a coronoid, 2 surangulars, an articular, 91 isolated teeth, 20 cervical, 40 dorsal, 4 sacral, and 18 caudal vertebrae, 34 vertebral fragments, 3 ribs, 2 humeral fragments, and 4 ilia. Since all remains are isolated bones, the basis for the referral of this material to Pannoniasaurus is based on similar methods used by other authors, such as Houssaye et al.
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An arrow cleft is present on midline between the dentaries and a large lingual foramen is present on the lower jaw. A medial boss is present on the retroarticular projection. Atychodracon, based solely on the holotype, has 29-30 neck vertebrae including the atlas bone and axis, about 32 tail vertebrae, a projection on the front surface of the cervical ribs, a straight preaxial humerus margin, poorly defined radius and ulna facets on the humerus, a slightly shorter humerus than femur, a shorter ulna than radius, and a tibia and fibula equal length. Among other rhomaleosaurids, the material of Atychodracon has been mainly referred to two genera prior to its separation, namely Rhomaleosaurus and Eurycleidus.
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"Biscoveosaurus" is the informal name of an ornithopod dinosaur specimen from the Early Maastrichtian age Snow Hill Island Formation of James Ross Island, Antarctica. It comes from the Cape Lamb Member of the formation, the same member as Morrosaurus, another basal ornithopod. As such, it's been suggested it may be a secondary specimen of that species, but as the holotype of Morrosaurus is fragmentary and doesn't overlap with the material of "Biscoveosaurus", this can't as yet be tested. The specimen consists of dentaries, teeth, a braincase, parts of the maxillae, forelimb elements, assorted vertebrae, and the pectoral girdle; this makes it unique compared to the other James Ross Island ornithopods, which don't presever both cranial and postcranial remains.
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Behind this expansion, the upper jaw had a notch bearing significantly smaller teeth, into which the also expanded tips of the dentaries (tooth bearing bones of the mandible) fit into, with a notch behind the expansion of the dentary. The maxillae (main upper jaw bones) were long and formed a low branch under the nostrils that connected to the rear of the premaxillae. The teeth at the frontmost part of the maxillae were small, becoming significantly larger soon after and then gradually decreasing in size towards the back of the jaw. left Lengthwise atop their skulls ran a thin and shallow sagittal crest that was usually tallest near or above the eyes, either becoming shorter or disappearing entirely towards the front of the head.
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The ventral surface of the basisphenoid process is quite smooth and foramina are visible above the sixth tooth on the lateral surface of the pterygoid as well as above the position between the sixth and seventh teeth on the medial surface. The squamosal bone is only represented by a few fragments, but could be noted for being laterally compressed and tall, as in other species of Prognathodon. Its posteroventral surface is concave for contact with the quadrate. The dentaries are fused with the posterior end of the splenial and the anterior blade of the prearticular and have a tooth count of 13, with at least eight teeth possessing subdental crypts with some replacement teeth having been found in the type specimen.
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Frič (1883) considered these fangs to have grown out of the vomers (from the front of the skull) or possibly the parasphenoid (from the back of the skull), but Carroll (1966) reconstructed the fangs as being part of the long pterygoid bones, which were originally reported as being toothless. This is consistent with the relationship between Boii and Asaphestera, as the latter possessed two fangs along the outer edge of each pterygoid about midway down the skull. The dentaries (main bones of the lower jaws) are also preserved and covered with teeth similar to those of the upper jaws. A row of small pits run from the symphysis (chin) along the upper portion of the outer face of the bones.
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It contains the right premaxilla, both maxillae, the left jugal, a part of the right lacrimal, the rear of a left nasal bone, the middle part of a right nasal bone, the skull roof from the frontal bones to the exoccipitals, both squamosals, both quadrate bones, the predentary of the lower jaws, both dentaries, a right surangular, eleven neck vertebrae, eleven back vertebrae, twenty-nine tail vertebrae, nineteen chevron bones, nineteen ribs, the entire pelvis, both lower legs, a right second metatarsal and a right fourth metatarsal. The bones have not been found in articulation. Specimen MOR 1097, a fragmentary skull of a subadult individual, was referred to the species. It had been found at a kilometre distance from the holotype.
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Today, the incomplete holotype specimen, catalogued as ANSP 10081, is the only definite specimen of Elasmosaurus. It was long exhibited, but is now stored in a cabinet with other assigned fragments. The specimen consists of the premaxillae, part of the hind-section of the right maxilla, two maxilla fragments with teeth, the front part of the dentaries, three more jaw fragments, two cranial fragments of indeterminable identity, 72 neck vertebrae, including the atlas and axis, 3pectoral vertebrae, 6back vertebrae, 4sacral vertebrae, 18 tail vertebrae, as well as rib fragments. In 2013 an incomplete neck vertebra centrum of the holotype that had been mentioned by Cope but thought to have been lost was rediscovered in storage by Sachs, and the neck vertebra count was revised from 71 to 72.
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Speculative restoration of P. walkeri, based on the related mosasaur Halisaurus Pluridens was a moderately large mosasaur at roughly 5 m (16.4 ft) in length if the proportions of the dentary and the rest of the animal matches that of Halisaurus. A feature that separates Pluridens not only from the rest of the Halisaurinae, but from the rest of the Mosasauridae at large is its unusually high tooth count, dentaries assigned to the genus preserve almost twice the amount of teeth found in most other mosasaur genera. Additionally, the dentary of Pluridens also has one of the narrowest profiles among the mosasaurs, with the only genus approaching a similarly narrow dentary being the mosasaurine Plotosaurus. This combination of features indicate a feeding niche and lifestyle unique among the mosasaurs.
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The higher neural spines and shorter femur (60–70%) distinguishes Rodhocetus from the more primitive Ambulocetus. The convex posterior surface of the exoccipital, shorter cervical vertebrae, and unfused sacral vertebrae distinguishes R. kasrani from Indocetus. In contrast to later archaeocetes such as Protocetus and later cetaceans, Rodhocetus retains external nares above upper canines, high neural spines on anterior thoracic vertebrae, and four sacral vertebrae with sacroiliac joints similar to those in land-mammals (suggesting a hip joint that could support the body weight.) Several cranial features identifies R. kasrani as an archaeocete: both the premaxillae and the dentaries are elongated, the frontal shield is wide, and the nuchal crest is high. The auditory bullae are large and dense but, there are no associated pterygoid fossae or air sinuses.
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Tadzhikosuchus is an extinct genus of alligatoroid crocodilian from the Late Cretaceous of Tajikistan. To date it is mostly known from partial dentaries that show it to have been very similar to Diplocynodon. The two are differentiated by subtle differences in tooth position and tooth socket shape, and by differences in stratigraphy (Diplocynodon is known from the Paleogene and Neogene, making it younger). Three species have been named: the type species T. macrodentis, described by Efimov in 1982 from the lower Santonian- age Upper Cretaceous Ialovachsk Formation of Kansai, Tajikistan, in the Fergana Basin of Tajikistan; T. neutralis from the same location, by Efimov in 1988; and T. kizylkumensis from Turonian-age rocks of the Upper Cretaceous Bissekty Formation of Dzharakhuduk, Uzbekistan, by Nesov and colleagues in 1989.
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Teeth The fossil material consists of dentaries and maxillae, hence the characters mentioned by the name Lycorhinus angustidens that Sidney H. Haughton attributed to the remains in 1924, where the generic name means "wolf snout", as it was at first misidentified as a cynodont, and the specific descriptor means "constricted tooth".S.H. Haughton, 1924, "The fauna and stratigraphy of the Stormberg Series", Annals of the South African Museum 12: 323-497 The holotype, SAM 3606, consists of a mandible found by Dr M. Ricono. Three other species of Lycorhinus have been named. Lycorhinus parvidens was created by Robert Broom and Lycorhinus tucki by Richard Anthony Thulborn in 1970 renaming Heterodontosaurus tucki,R.A. Thulborn, 1970, "The systematic position of the Triassic ornithischian dinosaur Lycorhinus angustidens", Zoological Journal of the Linnean Society 49: 235-245 but these have failed to find recognition.
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Endocranial reconstruction of AENM 2/121 based on a CT scan. Kundurosaurus is known from holotype AENM 2/921, a partial, disarticulated skull, including a nearly complete braincase (AENM 2/921 1-2), two quadrates (3-4), squamosal (5), postorbital (6), frontal (7) and parietal (8) bones. The referred specimens are AENM 2/45-46, two jugals; AENM 2/83-84, 2/86, maxillae; AENM 2/57-58, nasals; AENM 2/48, postorbital; AENM 2/19, quadrate; AENM 2/121, 2/928 partial braincases; AENM 2/846, 2/902, dentaries; AENM 2/906, scapula; AENM 2/913, sternal; AENM 2/117, 2/903, 2/907-908, humeri; AENM 2/905, ulna; AENM 2/904, radius; AENM 2/922, nearly complete pelvic girdle and associated sacral elements. These were found at the same level as the holotype, but may belong to other individuals.
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Other specimens were referred: MgD-Ij116, a skull and lower jaws of a juvenile; MgD-Ij 118, fragmentary postcrania and lower jaws of a juvenile; MgD-Ij119, a dentary and three neural arches; MgD-IjI20, two dentaries and loose teeth; MgD-JjI21, a maxilla fragment with four teeth of a juvenile; and MgD-JjI22, teeth. They were then named as a separate genus, Breviceratops, by Sergei Mikhailovich Kurzanov in 1990, the generic name combining the Latin brevis, "short", with a reference to the Ceratopsia.Kurzanov, S., 1990, "A new Late Cretaceous protoceratopsid genus from Mongolia", Palaeontological Journal, 24: 85-91 Kurzanov also referred an additional number of fossils from Khermin Tsav, the type locality of Bagaceratops, to the new genus. The Khermin Tsav specimens closely resemble Bagaceratops, which has led to the proposal that Breviceratops and Bagaceratops are synonymous.
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The carinae of the hind edges were also very modified, and bifurcated (split in two) near the cervix, where they formed a flattened triangular, raised facet, which projected from the tooth crown and contacted or approached the folded carinae on the front edge of the crowns behind them (this arrangement is present in teeth 2–12). Such split carinae are known from other tetanuran theropods, where they are considered abnormalities caused by trauma, aberrant tooth replacement, or genetic factors. Though the condition in Segnosaurus was similar, it was uniformly expressed across the teeth of both dentaries, and does not appear to have been an abnormality, but served to roughen the contacts between tooth bases. The 22nd and 23rd dentary teeth of Segnosaurus were significantly smaller than the rest, almost conidont, and had an additional third carina with denticles on their inner sides.
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Guyanancistus niger possesses a long pectoral-fin spine and white spots that differentiate it from G. nassauensis. Guyanancistrus nassauensis is morphologically discriminated from all congeners by a small adult size (largest specimen observed 61 mm SL; adult size likely reached around 40 mm SL), by a reduced number of anal-fin rays (4 branched rays vs 5, apart from exceptional specimens), and by a wide oval mouth with both large dentary and premaxillary tooth cups (in % of head length, respectively: 24.2–31.9, mean 27.6, vs 23.6 or less except in Guyanancistrus niger, and 25.4–31.4, mean 28.1, vs 24.5 or less). Only G. niger has dentaries nearly as large (22.5–26.3, mean 25.0% of HL) but its premaxillaries are shorter (21.7–23.6, mean 22.6% of HL). Guyanancistus longispinis possesses a long pectoral-fin spine and roundish yellow spots that differentiate it from G. nassauensis.
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The dentary is long and shallow, and has a butt joint as the contact with the coronoid series, indicating the dentary is loosely attached to the jaw. Similar to some tetrapods such as Acanthostega and Tulerpeton, the dentary's lateral surface is ornamented on the dorsal side with a smooth section only on the ventral margin. Another lower jaw specimen (LDM 81/552) is the only known complete Ventastega dentary, and shows Ventastega had 89 marginal teeth on each side of the jaw that are all approximately the same size, although they decrease in height as you move distally. Ventastega also has a pair of fangs on each dentary that are situated close to where the two dentaries meet at the most anterior part of the lower jaw, similar to Panderichthyesand Ichthyostega.. On the precoronoid and intercornoid, Ventastega has fangs pairs set within the marginal row of teeth.
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