Or, to put it another way, he takes the keratinous appendages of modern-day dinosaurs and crimps and cuts, glues and sews them to fit the bodies of undernourished mammals.
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"If these small bodies are melanosomes, they should be embedded in a keratinous matrix, since feathers contain beta-keratin," noted Mary Schweitzer, a biologist at NCS and a co-author of the study, in a statement.
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The keratinous shield thought to have covered the tip of the snout would have provided further protection.
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Viewed from above, the front and rear of the skull were expanded, with the broad front forming a duck-bill or spoon-bill shape. The beak was toothless, and both the upper and lower beaks were extended by keratinous material. Substantial remains of the keratinous upper beak are known from the "mummy" kept at the Senckenberg Museum.
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The second, less common type of lesion is distinctly KA-like, consisting of a crateriform keratinous center with an exuberant squamous epithelial proliferation.
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A keratinous covering would also allow greater surface area for the plates to be uses as a mating display structures, which could be potentially coloured like the beaks of modern birds. At the same time this finding implies that the use of plates for thermo-regulation may be less likely because the keratinous covering would make heat transfer from the bone highly ineffective.
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The palatines themselves preserve expanded, roughly textured pads that indicate the front of the roof of the mouth was covered in keratinous horn like the beak.
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Spadefoots are so-named for the large, keratinous metatarsal tubercles that are internally supported by a well-ossified prehallux, located on the outside edges of their feet.
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These horns are deeply grooved, suggesting that they were the covered by a keratinous sheath. These were presumably used for combat between individuals, as similar behaviour is known in extant species.
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The skull is well preserved for the most part, and it provides further evidence that some sauropods may have had a beak-like keratinous sheath covering the anterior of the snout.
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Fur seems to be absent on the underside of the abdomen. A keratinous spur on the rear leg may have been used to deliver poison, like the spur of the living platypus.
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However, fingers have some spines in males—a secondary sex characteristic, as are the black patches of keratinous spines in the chest. The holotype was destroyed by fire on 3 December 2007.
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Various phytosaurs have crests and similar ornamentions in their snouts. Nicrosaurus has a ridge along the snout that would have supported a keratinous crest in life, while Mystriosuchus westphali has several bony crests.
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A. kuehnii is a rare fungus found in North America and Mexico, with a few reports from Europe. Due to the limited available isolates, conclusion of its habitat cannot be drawn. Although it was mostly discovered in lizard or bat dung and keratinous soil, strains have been isolated from keratinous surfaces of animals such as fowl and deer horns. None of the species in Amauroascus is known to be a pathogen of animals, and no strains have been isolated from humans.
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Though the holotype specimen lacks cranial material, the preserved elements in therizinosaurids Erlikosaurus and Segnosaurus indicate that it had a relatively small skull with coarsely serrated teeth, and developed a prominent rhamphotheca (keratinous beak).
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The teeth of the animal were small, conical, and serrated, and were distributed irregularly in its jaws. The tip of the dentary had no teeth, and evidence suggests that it was covered by a keratinous beak.
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Moreover, the comparably narrow width of the snout could indicate selective feeding in this therizinosaurid. Lastly, the branch‐stripping behaviour of Erlikosaurus may have been compensated by the postcranial musculature. During the same year, Lautenschlager and team made digital models of the skull of Erlikosaurus to test the function the rhamphotheca (keratinous beak), finding that this structure in the jaws acted as a stress-mitigating structure. They concluded that keratinous beaks are beneficial to enhance the stability of the skull making it less susceptible to bending and/or deformation during feeding.
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This combined with other evidence points towards Odontocyclops possessing a keratinous beak. Lastly, the vomers of Odontocyclops are fused and they do possess a secondary palate that is relatively flat compared to other dicynodonts and contains low walls.
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Amauroascus kuehnii is a fungus in the phylum Ascomycota, class Eurotiomycetes. It is keratinophilic but not known to cause any human disease. It has been isolated from animal dungs, soil, and keratinous surfaces of live or deceased animals.
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Though horn cores are blunt, they may have had a similar form to modern bovid horns if there was a keratinous covering. However, this would be the only reported example of horns being used as hunting weapons in animals.
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Nevus comedonicus (also known as a "comedo nevus") is characterized by closely arranged, grouped, often linear, slightly elevated papules that have at their center keratinous plugs resembling comedones.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. .
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This species has been recorded to possess a distinctive earthy odour. It secretes extracellular keratinase and is a saprotroph on keratinous debris and soil. The fungus also produces a tube precipitin (TP) antigen which is a glycoprotein shared by the pathogenic fungus Coccidioides immitis.
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Cassowaries have small wings with 5–6 large remiges. These are reduced to stiff, keratinous quills, resembling porcupine quills, with no barbs. A claw exists on each second digit of the feet. The furcula and coracoid are degenerate, and their palatal bones and sphenoid bones touch each other.
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Lastly, the cerebellum is not very notorious as previous elements, it is elongated and stocky. Keratinous beaks, or rhamphothecae, are well documented among diverse groups within the Dinosauria. Ornithomimosaurs have solid evidence for it. However, this is not an indicative to suggest the lack of this anatomical feature in other groups.
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Uncinocarpus uncinatus is a species of microfungi that grows on dung and other keratinous materials such as bone. It was the second species to be designated as part of the genus Uncinocarpus. The species was first described by Randolph S. Currah in 1985; synonyms include Myxotrichum uncinatum and Gymnoascus uncinatus.
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Keratosis punctata of the palmar creases is a common skin disorder that occurs most often in black patients, with skin lesions that are 1 to 5mm depressions filled with a comedo-like keratinous plug.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. .
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Others, like the ostrich, have only two toes (didactyl feet). The first digit, called the hallux, is homologous to the human big toe. The claws are located on the extreme phalanx of each toe. They consist of a horny keratinous podotheca, or sheath, and are not part of the skeleton.
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Reactive perforating collagenosis is a rare, familial, nonpuritic skin disorder characterized by papules that grow in a diameter of 4 to 6mm and develop a central area of umbilication to which keratinous material is lodged.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders.
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Uncinocarpus orissi is a species of microfungus that grows on dung and other keratinous materials, such as hair. It was the third species to be designated as part of the genus Uncinocarpus by Canadian mycologists Lynne Sigler, Arlene Flis and J.W. Carmichael in 1998 as a synonym for Pseudoarachniotus orissi and Aphanoascus orissi.
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The callus is a hard, keratinous section of the frontal plate located highest on the forehead. It is generally more pigmented than the surrounding corium. Underneath the callus is a Malpighian layer of tissue that connects the structure to the maxilla. This layer is supplied with blood via vessel-containing dermal papillae.
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As suggested by their name, these frogs have hard, keratinous protrusions present on their feet, which help them to dig. Like most fossorial frogs, they dig backwards into the ground. They differ from true toads because they have vertical pupils and no parotoid gland. The American spadefoot toads are terrestrial when not underground.
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A nail is a horn-like keratinous plate at the tip of the fingers and toes in most primates. Nails correspond to claws found in other animals. Fingernails and toenails are made of a tough protective protein called alpha-keratin which is found in the hooves, hair, claws and horns of vertebrates.
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In life, a wrinkled and possibly keratinous skin would have covered these bones. The maxilla was short and contained 16 alveoli, some with short teeth that were flattened laterally with anterior and posterior serrations. The maxilla of Ekrixinatosaurus also exhibits a dorsally projected ascending ramus and a short rostral ramus, suggesting a relatively high skull.
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Besides hair, Spinolestes also had keratinous scutes. Uniquely among Mesozoic mammal fossils the internal organs are also preserved, deposits of iron marking the position of the liver and microscopic structures being interpreted as the bronchioles. These are separated by a curved line, assumed to be the thoracic diaphragm. The ear is very well preserved.
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The snout was long compared to other ornithomimids, although it was broader and more rounded at the tip than in other species. Gallimimus was toothless with a keratinous (horny) beak, and had a delicate lower jaw. Many of the vertebrae had openings that indicate they were pneumatic (air-filled). The neck was proportionally long in relation to the trunk.
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The upper tooth row of Neoaetosauroides runs anteriorly to the tip of the elongated snout, evidence that is incompatible with the theory of a keratinous beak proposed for other aetosaurs.Desojo, J. B. and Báez, A. M. (2007). Cranial morphology of the Late Triassic South American archosaur Neoaetosauroides engaeus: evidence for aetosaurian diversity. Palaeontology 50(1):267-276.
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A second species, T. navigans, lacked this prong, and had a much more vertical crest. Soft tissue impressions also show that the small bony crests were extended by a much larger structure made of a keratinous material. The complete crest of T. navigans rose in a sharp, sail-like "dome" high above the rest of the skull.
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Nyctosaurus sported a bizarre antler-like crest. The crests were only a few millimetres thin transversely. The bony crest base would typically be extended by keratinous or other soft tissue. Since the 1990s, new discoveries and a more thorough study of old specimens have shown that crests are far more widespread among pterosaurs than previously assumed.
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This part of their stomach is called the gizzard, and it is also covered in keratinous spines. These spines further aid in the grinding up and digestion of the pangolin's prey. Some species, such as the tree pangolin, use their strong, prehensile tails to hang from tree branches and strip away bark from the trunk, exposing insect nests inside.
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The odontoid may have been encased in a keratinous covering so that it could occlude with the teeth. Apart from the skull, the skeleton of Istiodactylus was similar to those of other ornithocheiroid pterosaurs. The vertebral column, forelimb, and trunk bones were pneumatised by air sacs. The neural arches of the vertebrae had tall, sloping laminae.
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In birds and turtles, the lips are hard and keratinous, forming a solid beak. Clevosaurids like Clevosaurus are notable for the presence of bone "lips"; in these species the tooth-like jaw projections common to all sphenodontians form a beak-like edge around the jaws, protecting the teeth within.Jones MEH (2009). "Dentary tooth shape in Sphenodon and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia)".
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These projections, like the horns of many modern animals, might have been displayed for species recognition or intimidation. In Arcovenator, the dorsal margin of the postorbital (and probably also the lacrimal) is thickened dorsolaterally, forming a strong and rugose bony brow ridge rising above the level of the skull roof. Possibly, this rugose brow ridge supported a keratinous or scaly structure for displays.
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This fungus is often found in soil that is rich in keratinous material. However, there are other factors that can influence its growth, such as pH, relative humidity, organic carbon, nitrogen and temperature. Microsporum audouinii appears to prefer a neutral pH in the range of 6.8-7.0 and room temperature for growth. Drastic increases or decreases in temperature can inhibit its growth.
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The iris is black with small, intense red spots. The dorsum, flanks, and upper surfaces of the limbs are covered with many small, low, rounded warts that give the skin a velvet-like appearance. The warts on the dorsum, head, and limbs terminate in a single fine, keratinous spine. The tympanum is distinct and slightly greater than half eye in diameter.
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Similar to other burrowing frogs, American spadefoot toads are about 2-3 inches in length with round, stocky bodies and eyes that bulge from their heads. The name “spadefoot” is derived from the keratinous bone in its hind legs that allow it to burrow within soil. The skin of the toad is grey or brown in appearance and smooth to the touch.
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It had a thicker layer of blubber than other members of the order, an adaptation to the cold waters of its environment. Its tail was forked, like that of whales or dugongs. Lacking true teeth, it had an array of white bristles on its upper lip and two keratinous plates within its mouth for chewing. It fed mainly on kelp, and communicated with sighs and snorting sounds.
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Lull, Richard Swann; and Wright, Nelda E. (1942). Hadrosaurian Dinosaurs of North America. p. 225. The skull was roughly triangular in profile.Lull, Richard Swann; and Wright, Nelda E. (1942). Hadrosaurian Dinosaurs of North America. pp. 151–164. One specimen preserved a soft tissue crest or wattle on the head. The beak was toothless, and both the upper and lower beaks were extended by keratinous material.
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Uncinocarpus reesii is a species of saprotrophic microfungi that grows in soil and on keratinous materials such as hair, feathers and skin. It was the first species to be designated as part of the genus Uncinocarpus, owing in part to its characteristic development of hooked (uncinate) appendages. As the closest non-pathogenic relative of Coccidioides immitis and C. posadasii, it has become a subject of research interest.
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The shell is divided into two sections: the upper or dorsal carapace, and the lower, ventral carapace or plastron. The upper carapace consists of the vertebral scutes, which form the central, elevated portion; pleural scutes that are located around the vertebral scutes; and then the marginal scutes around the edge of the carapace. The rear marginal scutes are notched. The scutes are bony keratinous elements.
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A prominent pair of horns protruded obliquely above the eyes. These horns, formed by the frontal bones, were thick and cone-shaped, but somewhat vertically flattened in cross-section, and measured in length. In life, they would probably have formed the bony cores of much longer keratinous horns. The proportionally small eyes were situated in the upper part of the keyhole shaped orbita (eye sockets).
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Skulls of C. sanctus and C. sp., with arrows indicating hyoid elements The skull morphology of Confuciusornis has been difficult to determine, due to the crushed and deformed nature of the fossils. The skull was near triangular in side view, and the toothless beak was robust and pointed. The front of the jaws had deep neurovascular foramina and grooves, associated with the keratinous rhamphotheca (horn-covered beak).
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While most extant birds have a single seamless rhamphotheca, species in a few families, including the albatrosses and the emu, have compound rhamphothecae that consist of several pieces separated and defined by softer keratinous grooves. Studies have shown that this was the primitive ancestral state of the rhamphotheca, and that the modern simple rhamphotheca resulted from the gradual loss of the defining grooves through evolution.
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Cutaneous horns, also known by the Latin name cornu cutaneum, are unusual keratinous skin tumors with the appearance of horns, or sometimes of wood or coral. Formally, this is a clinical diagnosis for a "conical projection above the surface of the skin." They are usually small and localized but can, in very rare cases, be much larger. Although often benign, they can also be malignant or premalignant.
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At the base of these tentacles within the buccal mass (analogous to the mouth) a hard keratinous beak would have bitten into the bodies of its prey, and is assumed to have been strong enough to breach the prey's exoskeleton or shell. Within the beaks of modern cephalopods a radula, or 'toothed' tongue is used to rasp out soft tissue from within the prey's shell.
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The surfaces of the premaxillae are rugose with the edges elevated above the body of the bone, suggesting that a keratinous shield would have been supported by the rugosities at the tip of the snout. Along the interpremaxillary suture, the area where the two premaxillae meet, the surface is smooth, giving the paired rugosity of the premaxillae the resemblance of a moustache in anterior view.
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The Iowa reports led cancer researcher Richard E. Shope to investigate, and he discovered the virus in 1933. He separated the virus from horny warts on cottontail rabbits, and made one of the first mammalian tumor virus discoveries. Shope determined the protrusions were keratinous carcinomas due to the infection of CRPV. Shope's research led to the development of the first mammalian model of a cancer caused by a virus.
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Their disposal tends to be similar to that of normal epidermis: immature/basal cells at the periphery, becoming more mature to the centre of the tumor masses. Tumor cells transform into keratinized squamous cells and form round nodules with concentric, laminated layers, called "cell nests" or "epithelial/keratinous pearls". The surrounding stroma is reduced and contains inflammatory infiltrate (lymphocytes). Poorly differentiated squamous carcinomas contain more pleomorphic cells and no keratinization.
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Size of Adeopapposaurus compared to a human. The type specimen, PVSJ568, includes a skull and most of a skeleton to just past the hips. The form of the bones at the tips of the upper and lower jaws suggests it had keratinous beaks. The fossils now named Adeopapposaurus were first thought to represent South American examples of Massospondylus; while this is no longer the case, Adeopapposaurus is classified as a massospondylid.
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H. semispinosus has hard keratinous quills located in the mid-dorsal region that act as a sounding device and is thought to be used for communication between mother and young and/or a warning signal to predators.Endo, H., Koyabu, D., Kimura, J., Rakotondraparany, F., Matsui, A., Yonezawa, T., ... & Hasegawa, M. (2010). A quill vibrating mechanism for a sounding apparatus in the streaked tenrec (Hemicentetes semispinosus). Zoological science, 27, 427-432.
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Most distinctively, it sported two parallel rows of tall spines down its neck and back, taller than in any other known sauropod. In life, these spines most likely could have stuck out of the body as solitary structures that supported a keratinous sheath. An alternate hypothesis, now less favored, postulates that they could have formed a scaffold supporting a skin sail. They might have been used for display, combat, or defense.
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Keratinous sheaths covering the spines were also shown in a 1999 skeletal restoration published by Salgado. Jack Bailey, in 1997, argued that the spines resembled those of sail-bearing pelycosaurs like Dimetrodon. According to this author, Amargasaurus might also have possessed such a sail, which might have been used for display. Unlike those of pelycosaurs, the neural spines of Amargasaurus were bifurcated, forming a double row along the neck and back.
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The nasal bones seem to be highly pneumatized. The lower part of the premaxillae (at the tip of the snout) features several irregularly distributed pits, which probably represent foramina which allowed blood vessels to flow, indicating a keratinous sheath (rhamphotheca) over a beak similar to ornithomimids. The ventral side (underside) of the premaxillae is highly broken up, which could indicate the bone was lightweight, perhaps being pneumatized. Corythoraptor was toothless.
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The discovery of an impression of the skin covering the dorsal plates has implications for all possible functions of stegosaurian plates. Christiansen and Tschopp (2010) found that the skin was smooth with long, parallel, shallow grooves indicating a keratinous structure covering the plates. The addition of beta-keratin, a strong protein, would indeed allow the plates to bear more weight, suggesting they may have been used for active defense.
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Dasypus are primitive mammals known for their hard armor like shell, called a carapace. Their ossified dermal plates compose a series of six to eleven movable bands covered by leathery keratinous skin, which surrounds and protects the body. A thin epidermal layer separates each of the armor bands, and joints in the shell allow for flexibility. The face, neck, and underside lack a bony covering and are instead covered with small bunches of hair.
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The sharp serrations of the canines were maintained by the action of the wear with the lower canines, a process known as thegosis. The convex upper portion of the maxilla is ornamented with extensive furrows and pits. This texturing has been correlated with an extensive network of blood vessels, which may suggest that the upper maxilla was covered by some form of soft tissue which tentatively has been hypothesized as a "horn covering" (keratinous structure).
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Pangolins have long, broad tails and small, conical heads with jaws that lack teeth. To replace the act of chewing, the pangolin stomach is muscular, with keratinous spines that project into the interior and contains small stones to mash and grind prey, similarly to a bird’s gizzard. Pangolins also have long, muscular tongues to reach and lap up ants and termites in cavities. Their tongues stretch so far, they are actually longer than their bodies.
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Internal anterior carapace of Elseya dentata. Pe = Peripheral, P1 = Pleural 1, BCS = Bridge Carapace Suture. The turtle shell is made up of numerous bony elements, generally named after similar bones in other vertebrates, and a series of keratinous scutes which are also uniquely named. Some of those bones that make the top of the shell, carapace, evolved from the scapula rami of the clavicles along with the dorsal and superficial migration of the cleithra.
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Elasmotherium is thought to have had a keratinous horn, indicated by a circular dome on the forehead, with a deep, furrowed surface, and a circumference of . The furrows are interpreted as the seats of blood vessels for horn-generating tissue. Restoration of E. sibiricum In rhinos, the horn is not attached to bone, but grows from the surface of a dense skin tissue, anchoring itself by creating bone irregularities and rugosities. The outermost layer cornifies.
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Tropidostoma is currently classified as an oudenodontid within the larger dicynodont clade Bidentalia. This clade is characterized collectively by their reduced dentition with only their maxillary tusks being intact. However, many species in this clade sporadically lack tusks completely and their fossils only hold evidence that they retained their keratinous beaks. Many Tropidostoma fossils previously collected have been misidentified as other species, such as of Oudenodon bainii due to their remarkable similarity.
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This process may also be augmented by induction of excess tumor necrosis factor in the blood serum. The inflammatory processes lead to the formation of keratinous plugs in skin pores, forming yellowish cysts and dark pustules. The associated pus is usually a color of green approximating that of a tennis ball. The skin lesions occur mainly in the face, but in more severe cases they involve the shoulders and chest, the back, and the abdomen.
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More fragmentary remains of Pterodactylus have tentatively been identified from elsewhere in Europe, as well as in Africa. Many studies conclude that Pterodactylus was a carnivore that probably preyed upon fish as well as other small animals. Like all pterosaurs, Pterodactylus had wings formed by a skin and muscle membrane stretching from its elongated fourth finger to its hind limbs. It was supported internally by collagen fibres and externally by keratinous ridges.
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Also, a club-like protrusion from the head is used to hold onto the female during mating. The keratinous eggs are released onto the muddy sediment of the ocean bottom, usually in shallower water. At first, the egg is a golden yellow color, but this transforms into brown, and finally, black right before hatching. The average amount of time in the egg is 8 months, and the embryo uses the yolk for all nourishment.
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Size comparison with an average human male Life restoration Archaeornithomimus was a medium sized ornithomimosaur, reaching long with a weight ranging from . Genus List for Holtz 2012 Weight Information Solid evidence coming from other ornithomimosaurian relatives suggest that Archaeornithomimus was a feathered animal, with very ratite-like feathers and equipped with a keratinous beak. The hindlimbs were robustly built. The third metatarsal was not pinched at the upper end, so the foot was not arctometatarsalian.
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The lower jaw tapered towards the front, and the dentary bone (the main part of the lower jaw) was robust. The front of the jaws were covered by a toothless keratinous beak (or rhamphotheca). The upper beak covered the front of the premaxilla bone and the lower beak covered the predentary, which are, respectively, the foremost bones of the upper and lower jaw in ornithischians. This is evidenced by the rough surfaces on these structures.
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The two premaxillae are very long and run up over the snout to meet the prefrontals at the orbit. At the anterior tip they are narrow and triangular in cross-section. They form the classic rhynchosaurian beak, and there is evidence on the fossil showing that it was probably covered by a keratinous sheath. The maxilla carries a massive tooth plate and has numerous foramina for nerves and blood vessels to reach the gums through.
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This is the ideal method of diagnosis for basal cell cancer. It can be used to diagnose squamous cell carcinoma and melanoma-in-situ, however, the doctor's understanding of the growth of these last two cancers should be considered before one uses the shave method. The punch or incisional method is better for the latter two cancers as a false negative is less likely to occur (i.e. calling a squamous cell cancer an actinic keratosis or keratinous debris).
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In the holotype, the horn core is long and wide at its base, but quickly narrows to only further up; it is in height. It is longer and lower in the skull of MWC 1. In the living animal, the horn would likely have been more elongated due to its keratinous sheath. Behind the nasal horn, the nasal bones formed an oval groove; both this groove and the nasal horn serve as features to distinguish Ceratosaurus from related genera.
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Skull cast, Dinosaur Discovery Museum, Kenosha, Wisconsin The skull, measuring in length, was proportionally shorter and deeper than in any other large carnivorous dinosaur. The snout was moderately broad, not as tapering as seen in more basal theropods like Ceratosaurus, and the jaws were curved upwards. As in other abelisaurids, the facial bones, especially the nasal bones, were sculptured with numerous small holes and spikes. In life, a wrinkled and possibly keratinous skin would have covered these bones.
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An additional skull described in 2011, specimen CPCA 3590, preserved more of the lower jaw, showing that like Tapejara, T. imperator had a large, asymmetrical "keel"-like crest on the underside of the lower jaw tip. Some Tupandactylus specimens preserve evidence of a keratinous beak at the jaw tips. However, this was restricted to the crested portion of the lower jaw, as one specimen also preserves pycnofibres (simple feather-like filaments) covering the jaws further back.
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From top to bottom: Tapejara wellnhoferi, Tupandactylus navigans, Tupandactylus imperator (drawn to scale) In some cases, fossilized keratinous beak tissue has been preserved, though in toothed forms, the beak is small and restricted to the jaw tips and does not involve the teeth. Some advanced beaked forms were toothless, such as the Pteranodontidae and Azhdarchidae, and had larger, more extensive, and more bird-like beaks. Some groups had specialised tooth forms. The Istiodactylidae had recurved teeth for eating meat.
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The Uropeltidae, the shieldtail or shield-tailed snakes, are a family of primitive, nonvenomous, burrowing snakes endemic to peninsular India and Sri Lanka. The name is derived from the Greek words ura ("tail") and pelte ("shield"), indicating the presence of the large keratinous shield at the tip of the tail. Seven or eight genera are recognized, depending on whether Teretrurus rhodogaster is treated in its own genus or as part of Brachyophidium. The family comprises over 50 species.
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However, Manning et al. argued that the claw instead served as a hook, reconstructing the keratinous sheath with an elliptical cross section, instead of the previously inferred inverted teardrop shape. In Manning's interpretation, the second toe claw would be used as a climbing aid when subduing bigger prey and also as a stabbing weapon. Life restoration of Deinonychus preying on a Zephyrosaurus using the sickle claw for prey restraint Ostrom compared Deinonychus to the ostrich and cassowary.
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The species itself commonly infects humans whom are closely tied to these areas because of agricultural work. In these areas, soil moisture is indicative role in the presence of the M. gypseum complex, areas with higher moisture tend to be preferred. Correlations between infections and soil types indicate that most improved soils of the clayey or clayey-sandy type are preferred, particularly those fertilized with keratinous manure. Additionally the fungus prefers soils with a pH of 7-7.5.
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Additional findings comprising forelimb and hindlimb elements have been discovered during the 1960s-1980s. Therizinosaurus comprises the single species T. cheloniformis, which could grow up from long and weigh possibly over . It had the longest known claws of any land animal, reaching up to in length. Unlike other therizinosaurs, the claws were very stiff and elongated, but like other members, it would have been slow, long-necked/high browser herbivore equipped with a keratinous beak and a wide torso.
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The front portion of the upper jaw (premaxilla) and tip of the lower jaw (predentary) lacked teeth and were probably covered in a beak. Studies of the bone surface show that at least the tips of the jaws supported a hard, keratinous beak similar to that found in modern birds. The palate (mouth roof) contained small pits that allowed the lower teeth to lock into place when the jaws were closed. They also retained a dinosaur-like joint between the lower jaw bones.
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Strickland stated that although not identical, these birds shared many distinguishing features of the leg bones, otherwise known only in pigeons. Sketch of the Oxford head made before it was dissected in 1848 Strickland and Melville established that the dodo was anatomically similar to pigeons in many features. They pointed to the very short keratinous portion of the beak, with its long, slender, naked basal part. Other pigeons also have bare skin around their eyes, almost reaching their beak, as in dodos.
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Harmer, S. F. & Shipley, A. E. (1899) Close-up of the head of a southern cassowary All three species have a keratinous skin-covered on their heads that grows with age. The casque's shape and size, up to , is species-dependent. Casuarius casuarius has the largest and Casuarius bennetti the smallest (tricorn shape), with Casuarius unappendiculatus having variations in between. Contrary to earlier findings, the hollow inside of the casque is spanned with fine fibres that are believed to have an acoustic function.
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Comparison of the casque of Corythoraptor and the cassowary Corythoraptor bore a tall crest on its head similar to that of the modern cassowary, with a thick perhaps keratinous bony shell casing. The crest is pneumatized and features several chambers separated by thin bony walls, though the crest of Corythoraptor is more pneumatized than that of the cassowary. This may have made the crest quite pliable, incapable of withstanding concussive force such as during head butting. Corythosaurus had a relatively large eyesocket.
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Hagfish have a unique dental plate inside of their mouths with a row of posterior and anterior keratinous grasping teeth on each side. This dental plate folds bilaterally helping with the grasping motion hagfish use to eat their prey. The dental plate protrudes out and folds onto the flesh of the prey and then retracts back into the hagfish's mouth. It may also use its slime to suffocate its prey though this is mostly used as a defense against predators.
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Therizinosaurids had more specialized skulls compared to primitive members such as Falcarius, which had a generalist, beak-less snout. They had relatively elongated snouts and the tip was covered with a rhamphotheca (keratinous beak) used during feeding. Although the extension of the beak on the dorsal surface of the snout is unknown, it is estimated that it slightly overlapped the nasal cavity as in some modern-day birds. The dentary (lower jaw) also developed a rhamphotheca, seen on the edentulous (without teeth) anterior-most end.
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In life, the knobs would have been covered by tough cartilaginous or keratinous integument, which would have made them appear even larger. Carpal spurs and knobs are also known from other extant as well as extinct birds. Within Columbidae, the crowned pigeons and the Viti Levu giant pigeon have outgrowths on the carpometacarpus which are similar to those of the female Rodrigues solitaire. Other well known examples are the steamer ducks, the torrent duck, sheathbills, screamers, the spur-winged goose, and the extinct Jamaican ibis, Xenicibis xympithecus.
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As in other ankylosaurs, thick triangular scutes projected from the postorbital bone, above and behind the eyes, as well as the jugal bone, below and behind the eyes. More typically for nodosaurids, leaf-shaped teeth lined both upper and lower jaws, used for cutting plant material. The front end of the skull is unknown, but there would have been a sharp bony ridge (tomium) at the end of both upper and lower jaws, as seen in other ankylosaurs. This ridge probably would have supported a keratinous beak.
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As for other therizinosaurids, it had a keratinous beak used when feeding, stocky feet with four weight-bearing toes and large flattened claws. Nanshiungosaurus is classified as a therizinosaurian dinosaur. Along with Therizinosaurus and Segnosaurus, Nanshiungosaurus was one of the earliest therizinosaurs to be described and named. The unusual shape of the pelvis led Dong—the original describer—to interpret the remains as belonging to some dwarf sauropod, but during the 1990s the genus was recognized as a segnosaur (now therizinosaur) based the pelvic similarities with Segnosaurus.
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The anuran larva or tadpole has a single central respiratory spiracle and mouthparts consisting of keratinous beaks and denticles. Panamanian golden frog (Atelopus zeteki). Frogs and toads are broadly classified into three suborders: Archaeobatrachia, which includes four families of primitive frogs; Mesobatrachia, which includes five families of more evolutionary intermediate frogs; and Neobatrachia, by far the largest group, which contains the remaining families of modern frogs, including most common species throughout the world. The suborder Neobatrachia is further divided into the two superfamilies Hyloidea and Ranoidea.
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The majority of Kembawacela specimens have these tusks, and it is possible that they were sexually dimorphic in this species. These tusks face slightly out to the sides, but do not sit out on a prominent caniniform process projecting from the jaw margin like in some other dicynodonts. Aside from the tusks, Kembawacela was otherwise toothless, and possessed a keratinous beak at the tips of its jaws, as is typical of dicynodonts. The beak was relatively broad and blunt, and the tip of the upper jaw was arched upwards.
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The distribution of M. nanum is worldwide, including North and South Americas, Canada, Europe, the Middle East, Australia, and Asia. Microsporum nanum and several other dermatophytes were isolated from eleven soil samples of hospitals and public places at Gulbarga, India. Keratinous wastes such as human dander and feathers of birds were suspected to provide a growth medium for these keratinophilic fungi. Microscporum nanum was observed much more frequently in hospital soil than in public places; the percentage was 45.4% and 33.3% of the total number of the observed keratinophilic fungi respectively.
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It had a wide muzzle filled with more than 500 teeth, which were replaced at a rapid rate: around every 14 days. The jaws may have borne a keratinous sheath. Unlike other tetrapods, the tooth-bearing bones of its jaws were rotated transversely relative to the rest of the skull, so that all of its teeth were located far to the front. Nigersaurus and its closest relatives are grouped within the subfamily Rebbachisaurinae (formerly thought to be grouped in the eponymous Nigersaurinae) of the family Rebbachisauridae, which is part of the sauropod superfamily Diplodocoidea.
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The lower jaw was S-shaped and divided into the subcylindrical transverse ramus, which contained the teeth, and the back ramus, which was more lightweight and was the location for most of the muscle attachments. The jaws also contained several fenestrae, including three that are not present in other sauropods. The front ends of the jaws had grooves that indicate the presence of a keratinous (horny) sheath. Nigersaurus is the only known tetrapod animal to have had jaws wider than the skull and teeth that extended laterally across the front.
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They grow from a permanent outgrowth of the frontal bone called the pedicle and can be branched, as in the white- tailed deer (Odocoileus virginianus), or palmate, as in the moose (Alces alces). Ossicones are permanent bone structures that fuse to the frontal or parietal bones during an animal's life and are found only in the Giraffidae. Pronghorns, while similar to horns in that they have keratinous sheaths covering permanent bone cores, are deciduous. All these cranial appendages can serve for posturing, battling for mating privilege, and for defense.
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Frontal view of skull Harrington's mountain goat was first described in the 1930s by paleontologist Chester Stock. Stock based his initial description on finds of skull fragments and metapodial bones from Smith Creek Cave in the Great Basin of Nevada. In 1937 he authored a Bulletin of the Southern California Academy of Science article titled "A new mountain goat from the Quaternary of Smith Creek Cave, Nevada". Later finds in Mexico, Colorado, Nevada, Utah, New Mexico, and the Grand Canyon have included intact skulls, metapodials, keratinous horn sheaths, dung, hair, muscle and ligament.
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Keuleman's illustration of the mount shows the present pose, so Forbes was either incorrect or a new pose was based on Keuleman's image. The Liverpool specimen is in good condition, although it has lost some feathers from its head and neck. The bill is broken, and its rhamphotheca (the keratinous covering of the bill) is missing; the underlying bone was painted red to simulate an undamaged bill, which has caused some confusion. The legs have also been painted red, and there is no indication of their original colouration.
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The color of its smooth skin ranges from shades of dark-gray to maroon-brown on its top surface, which is covered in irregular spots of pale yellow, orange, and red markings and has a red stripe along the center of its back. Keratinized spades on the inside of each hind foot aid it in digging. The snout is covered in epidermal armor of small keratinous spines and the lips are doubled sealed by secretions from submandibular glands. Its eyes are relatively small, and the tympanum is not visible.
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Hallett and Wedel also hypothesized that rival males might have interlocked their spines for neck wrestling. Pablo Gallina and colleagues (2019) described the closely related Bajadasaurus, which had neural spines similar to those of Amargasaurus, and suggested that both genera employed them for defense. A defense function would have been especially effective in Bajadasaurus as the spines were directed forwards and would have reached past the tip of the snout, deterring predators. The keratinous sheath that likely covered the spines might have extended their length by 50%, as seen in some modern even-toed ungulates.
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Like other members of their family, Therizinosaurus had a proportionally small skull bearing a keratinous beak atop the long neck, with bipedal gaits and a heavy, broad belly for foliage processing with the addition of sparse feathering. Its hindlimbs ended in four functionally, weight-bearing toes unlike other theropod groups in which the first toe was reduced to a dewclaw. In 2010, Senter and James used hindlimb length equations to predict the total length of the hindlimbs in Therizinosaurus and Deinocheirus. They concluded that an average Therizinosaurus may have had approximately long legs.
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In 2016 a morphological study showed that Tullimonstrum may have been a basal vertebrate, and thus a member of the phylum Chordata, with one study suggesting Tullimonstrum may be closely related to modern lampreys. This affinity was attributed based on pronounced cartilaginous arcualia, a dorsal fin and asymmetric caudal fin, keratinous teeth, a single nostril, and tectal cartilages like in lampreys. McCoy et al. raised the possibility that Tullimonstrum belongs to the ancestral group of lamprey, but it also has many features not found in Cyclostomes (lampreys and hagfishes).
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The Shope papilloma virus (SPV), also known as cottontail rabbit papilloma virus (CRPV) or Kappapapillomavirus 2, is a papillomavirus which infects certain leporids, causing keratinous carcinomas resembling horns, typically on or near the animal's head. The carcinomas can metastasize or become large enough to interfere with the host's ability to eat, causing starvation. Richard E. Shope investigated the horns and discovered the virus in 1933, an important breakthrough in the study of papillomaviruses and neoplasia. The virus was originally discovered in cottontail rabbits in the Midwestern U.S., but can also infect brush rabbits, black-tailed jackrabbits, snowshoe hares, and European rabbits.
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If a tortoise is dehydrated or unable to access conditions which are sufficiently moist, the keratinous layers which would otherwise form at the edges of scutes grow beneath the existing hardened shell causing a stacking effect which pushes shell growth upwards rather than outwards and exerts pressure on the skeleton beneath the shell. If severe, this leads to spinal and physical malformation. Other factors which may also contribute to pyramiding include the consumption of excessive animal or vegetable protein; inadequate calcium, UVB and/or vitamin D3; poor nutrition. Pyramiding may also be a visible sign of metabolic bone disease (MBD) in tortoises.
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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.
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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.
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Both Abrictosaurus and Heterodontosaurus had very large eyes. Underneath the eyes, the jugal bone projected sideways, a feature also present in ceratopsians. As in the jaws of most ornithischians, the anterior edge of the premaxilla (a bone at the tip of the upper jaw) was toothless and probably supported a keratinous beak (rhamphotheca), although heterodontosaurids did have teeth in the posterior section of the premaxilla. A large gap, called a diastema, separated these premaxillary teeth from those of the maxilla (the main upper jaw bone) in many ornithischians, but this diastema was characteristically arched in heterodontosaurids.
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As in other oviraptorids, it had a pair of tooth-like projections on the palate that were directed downwards (a feature that has been called "pseudo- teeth"). Nemegtomaia had small foramina (openings) on the sides of the suture (joint) between the premaxillae at the front of the snout, which may have been nutrient openings (and which indicate the presence of a keratinous bill). The lower jaw was short and deep, with a convex lower surface, and reached 153 mm (6 in) in length. The dentary bone of the lower jaw reached 50 mm (2 in) at its highest point.
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The tongue is protruded by contracting circular muscles that change the shape of the tongue and force it forwards and contracting two genioglossal muscles attached to the caudal end of the tongue and to the mandible. The protruded tongue is stiffened by a rapid flow of blood, which allows it to penetrate wood and soil. Retraction requires the contraction of two internal longitudinal muscles, known as the sternoglossi. When the tongue is retracted, the prey is caught on backward-facing keratinous "teeth", located along the roof of the buccal cavity, allowing the animal both to capture and grind food.
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There is a large diastema, or gap, between the keratinous beak on the front of the mouth and the main chewing teeth in the side of the mouth, which would allow the two sections to work independently, so Altirhinus could crop with its beak while simultaneously chewing with its teeth. Many herbivorous mammals show a similar adaptation and can crop with their incisors without disturbing their chewing molars. Altirhinus was one of a number of advanced iguanodontians with snouts expanded outwards towards the end. This is quite possibly an example of convergent evolution with hadrosaurids, famous for their wide "duckbill" snouts.
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Antlers (such as on deer) were derived from bone tissue: when mature, the skin and fur covering of the antlers, termed "velvet", is sloughed and scraped off to expose the bone of the antlers. Pronghorn were unique when compared to their relatives. Each "horn" of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. As in the Giraffidae, skin covers the bony cores, but in the pronghorn it develops into a keratinous sheath which is shed and regrown on an annual basis.
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The margins of the opening are smooth, and the inner border has fenestration connecting it to the inner structure of the crest. The back of the crest ended in a prominent V-shaped notch, a unique feature of this species. Although other parts of the crest have V-shaped breaks, the V shape at the end does not appear to have been due to breakage; the margins of the bone can be seen there, still encased by matrix. The crest probably had a keratinous (horny) covering and may have been extended by soft tissue in some areas, but the extent of this is unknown.
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These two fossil skulls had soft tissue preservation, and both had keratinous beaks with vertical grooves extending ventrally from the bony upper mandible. These structures are reminiscent of the lamellae seen in ducks, in which they function to strain small edible items like plants, forams, mollusks, and ostracods from the water. The authors further noted that ornithomimids were abundant in mesic environments, and rarer in more arid environments, suggesting that they may have depended on waterborne sources of food, possibly filter feeding. They noted that primitive ornithomimids had well developed teeth, while derived forms were edentulous and probably could not feed on large animals.
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Hadrosaurus were ponderously-built animals equipped with keratinous beaks for cropping foliage and a specialized and complex dentition for food processing. Hadrosaurus foulkii, the only species in this genus, is known from a single specimen consisting of much of the skeleton and parts of the skull. The specimen was collected in 1858 from the Woodbury Formation in New Jersey, US, representing the first dinosaur species known from more than isolated teeth to be identified in North America. Using radiometric dating of bivalve shells from the same formation, the sedimentary rocks where the Hadrosaurus fossil was found have been dated at some time between 80.5 and 78.5 million years ago.
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Aetiocetus is a genus of extinct basal mysticete, or baleen whale that lived , in the late Oligocene in the North Pacific ocean, around Japan, Mexico, and Oregon, U.S. It was first described by Douglas Emlong in 1966 and currently contains known four species, A. cotylalveus, A. polydentatus, A. tomitai, and A. weltoni. These whales are remarkable for their retention of teeth and presence of nutrient foramina, indicating that they possessed baleen. Thus, Aetiocetus represents the transition from teeth to baleen in Oligocene mysticetes. Baleen is a highly derived character, or synapomorphy, of mysticetes, and is a keratinous structure that grows from the palate, or roof of the mouth, of the whale.
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The lower jaw did not have a coronoid process or a supradentary bone, the lack of which is a common feature of beaked theropods (ornithomimosaurs, oviraptorosaurs, therizinosaurs and birds), but unusual among theropods in general. The jaws of Gallimimus were edentulous (toothless), and the front part would have been covered in a keratinous rhamphotheca (horny beak) in life. The beak may have covered a smaller area than in North American relatives, based on the lack of nourishing foramina on the maxilla. The inner side of the beak had small, tightly packed and evenly spaced columnar structures (their exact nature is debated), which were longest at the front and shortening towards the back.
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Therizinosaurids were generally large and very robustly built animals that had a near convergent body plan with the more recent (and also extinct) ground sloths. The largest genera of the group are Therizinosaurus and Segnosaurus, which were about and long, respectively. The physiology of therizinosaurids include a broad and rounded belly supported by a wide and robust pelvis with thick hind-limbs composed of very sout, four-toed feet, a strong arm build with enhanced hand flexibility, elongated hand claws, and a highly derived, nearly avian inner- ear. Traits that are also well-known include an elongated neck, a prominent keratinous beak and a prosauropod-like dentition that differs from all theropods.
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Grandry corpuscles are found in the superficial portion of the dermis in bill skin and oral mucosa of aquatic bird species. The specific location in the dermis varies between and within species; Grandry corpuscles have been observed at depths below the epidermis of 20-150 μm in domestic geese, 1-80 μm in greater white-fronted geese, and 50-100 μm in mallards. In the tip of the bills of ducks and geese, Grandry corpuscles can also be found within dermal papillae which extend through tubules into the maxillary and mandibular nails of the beak. These papillae, which contain many mechanoreceptors and end in keratinous caps, make up a distinct sensory region known as the bill tip organ.
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The flexor tubercle, a large bump near the base, served as an attachment site for flexor muscles - the larger it was, the greater the slashing strength. Dakotaraptor has a flexor tubercle that is larger relative to overall claw size than it is in other discovered dromaeosaurids, potentially giving it the strongest slashing strength of any known member of this group. The flexor tubercle on the third claw of the foot is almost non-existent, very reduced in size compared to other dromaeosaurids, suggesting a more minimized use of that claw. As these are the bony cores of the claws, they would have been covered in a keratinous sheath that extended the "nail" and ended in a sharp tip.
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In the natural environment, U. reesii is commonly found growing in soil and on keratinous materials, and is found over a wide geographic range. Though there are no recorded cases of disease caused by U. reesii, there is evidence to support the hypothesis that the species is the root of the evolutionary branch from which pathogenic species in the Onygenales arose. The ability of U. reesii to shift from plant to animal substrates are theorized to have led to development of pathogenicity in several Coccidioides and Paracoccidioides species, both of which are highly genetically similar to U. reesii. Another related Uncinocarpus species, U. orissi, has been implicated in one deep skin infection and two pulmonary infections of humans.
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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).
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Life restoration Suzhousaurus was one of the largest known Early Cretaceous therizinosauroids, with a length of and a ponderous weight of approximately . Suzhousaurus can be differentiated from all other therizinosaur taxa in having a round top border of preacetabular projection of ilium, a foramen on the obturator area with a total width greater than its height from the top to the bottom, a relatively short pubis with a deep and wide obturator notch, and the ischiadic shaft is deflected towards the rear. Like other therizinosauroids, Suzhousaurus developed a prominent keratinous beak, had stocky/robust hindlimbs, a large belly and a reduced tail. Feather impressions from the therizinosauroids Beipiaosaurus suggest at least a partial feathering in Suzhousaurus.
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Gregory Paul, in 1994, considered this possibility unlikely, noting that neck sails would have reduced neck flexion, and that the spines were circular in cross-section rather than flattened as is the case in sail-bearing animals. Instead, he found that this shape indicates that the spines supported a keratinous sheath that would have extended the length of the spines in life. The spines could have been used for display or as weapons both against predators and members of the same species, as the animal might have been able to point its most anterior spines forward by bending its neck. He also hypothesized that the spines could have been clattered together to generate sound.
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The skull of Ufudocyclops superficially resembles Angonisaurus, being relatively tall and notably broad behind the snout, with large, sideways facing eyes and prominent tuskless caniniform processes on the maxilla that project away down and forwards from the snout, flaring out slightly to sides, with blunted tips. The lower surfaces of the maxilla are heavily pitted and rugose, as is the premaxilla and the palate on the roof of the mouth. These textures correspond to the eponymous tortoise-like keratinous beak typical of dicynodonts like Ufudocyclops. The isolated tip of the premaxilla demonstrates that these pits are superficial and do not continue deeper into the bone, as the inner texture of the bone is smooth and tabulate, and so are not foramina.
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The postcanines of Clelandina were replaced by a smooth ridge unlike dicynodonts which have a blade-like keratinous ridge, and it may have predominantly gone after prey it could swallow whole. Gorgonopsian taxa did coexist with each other—as many as 7 at one time–and the fact that some rubidgeines possess postcanines while some other contemporary ones do not suggests that they practiced niche partitioning and pursued different prey items. The elongated canines have generally been thought to have been instrumental in their hunting tactics. The gorgonopsian jaw hinge was double jointed and made up of somewhat mobile and rotatable bones, which would have allowed them to open their mouths incredibly wide–perhaps in excess of 90°–without having to unhinge the jaw.
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The head is small relative to the large body, and quite distinctive in shape, being flat and blunt at the front, like the snout of a pig. Some teeth are chisel-shaped, small and leaf-like, indicating a probable herbivorous diet, although peg-like teeth and a keratinous snout have been considered possible adaptations in some species for feeding on colonial insects. A study of the braincase of Stagonolepis robertsoni has shown that there are similarities between it and those of crocodylomorphs, which may indicate a close relationship.Archosaurian Anatomy and Palaeontology: Essays in Memory of Alick D. Walker, DB Norman & DJ Gower (eds.) Aetosaurs had a "pillar-erect" erect limb posture similar to that seen in Rauisuchia, a related group of Triassic archosaurs.
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Zanno and colleagues found that Ornithomimosauria, Therizinosauria, and Oviraptorosauria had either direct or morphological evidence for herbivory, which would mean either this diet evolved independently multiple times in coelurosaurian theropods or that the primitive condition of the group was at least facultative herbivory with carnivory only emerging in more derived maniraptorans. The skull of therizinosaurids was specialized as well, as it was likely capped off with a beak-like rostrum in the front. It has been argued that this rostrum was likely covered with a keratinous beak, an adaption that might have helped to enhance cranial stability by mitigating the stress and strain experienced by the skull during feeding. As indicated by their respective dental morphologies, the contemporaneous therizinosaurids Erlikosaurus and Segnosaurus were separated by niche partitioning.
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Hadrosaurid-therizinosaurid occurrence in the Cantwell Formation Therizinosaurids were very specialized herbivores that evolved a convergent life-style to the more recent ground sloths. They are so similar in some aspects that this idea is also reflected in the name of several species, such as Nothronychus (slothful claw) or Suzhousaurus megatherioides (Megatherium-like). Multiple of their anatomical and physiological traits such as leaf-shaped, coarsely serrated teeth, strong arm build with large claws, a notoriously elongated neck and the development of a keratinous beak situate therizinosaurids as browser herbivores. More specifically, therizinosaurids inhabited high-browsing niches in their ecosystems and commonly lived in semi-arid to wetland-like habitats composed of high vegetation as seen on the fluvial-lacrustrine setting of most specimens.
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Chevron bones of this particular form were initially believed to be unique to Diplodocus; since then they have been discovered in other members of the diplodocid family as well as in non-diplodocid sauropods, such as Mamenchisaurus. Restoration of D. carnegii with horizontal neck, flexible whip tail, keratinous spines and nostrils low on the snout Like other sauropods, the manus (front "feet") of Diplodocus were highly modified, with the finger and hand bones arranged into a vertical column, horseshoe-shaped in cross section. Diplodocus lacked claws on all but one digit of the front limb, and this claw was unusually large relative to other sauropods, flattened from side to side, and detached from the bones of the hand. The function of this unusually specialized claw is unknown.
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The New Zealand hagfish has a skull but no jaw or true vertebral column, it instead has a skeleton made up of cartilage.(Encyclopedia of Britannica, 2011) The rounded mouth of the hagfish is surrounded by 6 barbels, above that is their singular nasal passage and just inside the mouth is a dental plate with a row of posterior and anterior keratinous grasping teeth on each side. It has seven pairs of gill pouches and forming a line down both the lower sides of its body are pores which often many of them are ringed with a white colour and are used for secreting a snot-like slime which expands out once it has contact with the sea water.(Bray, n.
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The skull of Hoffstetterius is high and elongated; in the holotype specimen it measures in length, while in the juvenile specimen it reaches . The most notable characteristic of this is the elevation of the frontal bone over the nasals, forming a large sagittal crest, which is more developed in the adult individual, and also presents in the anterior frontal area a sort of triangular "shield", which may have served as a point of attachment for a keratinous horn, as in modern rhinoceroses and some toxodontids such as Trigodon and Paratrigodon. In dorsal view, the skull is triangular in shape. The mandible has a notorious projection pointing downwards into the mandibular ramus, at the level of the lower third molar (m3), a feature seen in other toxodontids such as Mixotoxodon and Pericotoxodon.
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E. annectens skull preserving the keratinous beak (partially removed on the right side by accident), Natural History Museum of Los Angeles Between the mid-1980s and the first decade of the 2000s, the prevailing interpretation of how hadrosaurids processed their food followed the model put forward in 1984 by David B. Weishampel. He proposed that the structure of the skull permitted motion between bones that resulted in backward and forward motion of the lower jaw, and outward bowing of the tooth-bearing bones of the upper jaw when the mouth was closed. The teeth of the upper jaw would grind against the teeth of the lower jaw like rasps, processing plant material trapped between them. Such a motion would parallel the effects of mastication in mammals, although accomplishing the effects in a completely different way.
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Snout regions of MOR 591 and 485 The bosses on the skull of Achelousaurus may have been covered in a keratinous sheath in life, but their shape in a living animal is uncertain. In 2009, the paleontologist Tobin L. Hieronymus and colleagues examined correlations between skull morphology, horn, and skin features of modern horned animals, and examined the skull of centrosaurine dinosaurs for the same correlates. They proposed that the rugose bosses of Achelousaurus and Pachyrhinosaurus were covered by thick pads of cornified (or keratinized) skin, similar to the boss of modern muskoxen (Ovibos moschatus). The nasal horncore of adult Achelousaurus had an upward slant and its upper surface had correlates for a thick epidermal (outer layer of skin) pad that graded into correlates for a cornified sheath on the sides.
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The horns themselves have a rough, grooved texture that implies they were covered with a keratinous sheath of horn in life, also like ceratopsid horns, and so would have likely been longer than the bony cores indicate. The bones of the skull beneath the horns are unusually thick, and in the larger individuals the bones of roof of the skull (the nasal, prefrontal, frontal and postfrontal) are fused together on each side. Life restoration The teeth of Shringasaurus are low and leaf-shaped (lanceolate) with large denticles on either side, similar in shape to those of Azendohsaurus but lacking the prominent expansion above the root, like the teeth of Pamelaria. Because the skull and jaws are incompletely known, the total tooth count of Shringasaurus is unknown, but like Azendohsaurus it had four teeth in each premaxilla.
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Lower jaws of Erlikosaurus (bottom) and Segnosaurus (top) compared In 2009, Zanno and colleagues stated therizinosaurs were the most-widely regarded candidates for herbivory among theropods based on the small, densely packed, coarse serrations; lance-shaped teeth with a relatively low replacement rate; a well- developed keratinous beak; long neck for browsing; relatively small skulls; a very large gut capacity as indicated by the rib circumference at the trunk and the outwards flaring processes of the ilia; and the notable lack of cursorial adaptations in the hind limbs. All of these features suggest that members of this family feed on vegetation, as well as pre-processing it within their mouths to begin the breakdown of cellulose and lignin. This is perhaps even more so true for therizinosaurids, which seem to have further exploited these characters. One of the most notable adaptations in advanced therizinosaurids are the four-toed feet, which had a fully functional, weight-bearing first digit that was likely adapted to slow life-style.
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Several characteristics are indicative of a rhamphothecae, such as an edentulous premaxilla with a thin, tapering lower edge, the successive loss of maxillary and dentary teeth, a mandibular concavity in the lower side, the displacement of the lower surface in the dentary, and a rostral projection of the mandibular symphysis. In Erlikosaurus, the presence of a keratinous beak on the maxilla and premaxilla can be inferred by the presence of numerous neurovascular foramina on the rostral and lateral surfaces in the skull, furthermore, it bears all the mentioned features above, however, it is unclear the extension of the beak. The preserved rhamphotheca in specimens of Gallimimus and Ornithomimus evidences that the keratin sheath covered the premaxilla and overlapped it on the lower side by a few millimeters. In some extant birds, the rhamphotheca is typically restricted to the premaxilla and maxilla, although in some cases it partially covers the nasal process in some birds.
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Stegoceras was better capable of dissipating force than artiodactyls that butt heads at high forces, but the less vascularized domes of older pachycephalosaurs, and possibly diminished ability to heal from injuries, argued against such combat in older individuals. The study also tested the effects of a keratinous covering of the dome, and found it to aid in performance. Though Stegoceras lacked the pneumatic sinuses that are found below the point of impact in the skulls of head-striking artiodactyls, it instead had vascular struts which could have similarly acted as braces, as well as conduits to feed the development of a keratin covering. Two S. validum domes with lesions (arrows) shown from above In 2012, Schott and Evans suggested that the regularity in squamosal ornamentation throughout the ontogeny of Stegoceras was consistent with species recognition, but the change from flat to domed frontoparietals in late age suggests that the function of this feature changed through ontogeny, and was perhaps sexually selected, possibly for intra-specific combat.
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Sacrum of holotype BYU 9047 Soft tissue from the mouth region of SMA 0002 made researchers propose in 2016 that the tooth crowns were covered by gingival tissue, and perhaps a keratinous beak. The diagnostic characters for Cathetosaurus are: the pelvis is rotated anteriorly, such that the pubis projects posteroventrally, and the ischium projects posteriorly (1), lateroventrally projecting spurs in the neural spines of the last dorsals (2); posterior cervical and anterior dorsal diapophyses bearing an anterior projection lateral to the prezygapophyses (3); frontals with anterior midline projection into the nasals (4); trapezoidal supraoccipital (more expanded dorsally than ventrally) (5); lateral spur on the dorsal part of the lacrimal (6); fenestrated pterygoid (7); and the large pineal foramen between the frontals (8). Because of this, the proportions of the genus are extremely unusual: it has a very large skull relative to the axial skeleton, the limbs are short relative to the axial skeleton, the ribcage is extremely deep, so that the bottom of the ribcage is below the knee level. These features, and the rotation of the pelvis provided larger belly volume to the species.
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