8 -10 feet. The authors said the feathers belonged to a type of non-flying dinosaur. This could be for one of two reasons: either the animals simply did not have feathers, or these earlier dinosaurs have been fossilised in rocks that are not conducive for the preservation of soft tissues. Feathered Reptiles Ruled Earth's Skies. Farther posteriorly, the proportionately larger the cervicals become, although they do not change greatly in anything other than size. Fossil footprints and detailed studies of its anatomy have proven that Stegosaurus didn't drag its tail on the mud, but actually walked erect, like an elephant, with its tail held horizontally, parallel to the ground. [80] Christiansen and Tschopp (2010) state that the presence of a smooth, insulating keratin covering would have hampered thermoregulation, but such a function cannot be entirely ruled out as extant cattle and ducks use horns and beaks to dump excess heat despite the keratin covering. [2] Because of this, the International Code of Zoological Nomenclature decided to replace the type species with the more well known species Stegosaurus stenops. [26] The Sauriermuseum found several partial Stegosaurid skeletons throughout their excavations at Howe Quarry, Wyoming in the 1990s, though only Sophie has been described in detail. The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs. The phalangeal formula is 2-2-2-2-1, meaning the innermost finger of the fore limb has two bones, the next has two, etc. The stegosaurus is an immense yet stupid herbivore often found in the plains and jungles, where it feasts on grasses, plants, and leaves. "Log on!" Jason shouted. A study of pterosaur fossils published . Researchers found many North American specimens in Colorado, Utah, and Wyoming. Which dinosaurs did not have feathers? [5] The majority of the fossils came from Quarry 13, including the type specimen of Stegosaurus ungulatus (YPM 1853), which was collected by Lakes and William Harlow Reed the same year and named by Marsh. [35], The long and narrow skull was small in proportion to the body. Like Marsh's reconstruction, Knight's first restoration had a single row of large plates, though he next used a double row for his more well-known 1901 painting, produced under the direction of Frederic Lucas. The endocast showed the brain was indeed very small, the smallest proportionally of all dinosaur endocasts then known. [45] Bakker stated that Stegosaurus could flip its osteoderms from one side to another to present a predator with an array of spikes and blades that would impede it from closing sufficiently to attack the Stegosaurus effectively. As to the number of eggs, incubation time, and parental care, we simply dont know yet. And both of them bear battle . [4] Marsh also incorrectly referred several fossils to S. armatus, including the dentary and teeth of the sauropod Diplodocus and putting sauropod limb bones and an Allosaurus tibia under YPM 1850. Feathers are thought to have evolved from. [9][11] This first reconstruction, of S. ungulatus with missing parts filled in from S. stenops, was published by Marsh in 1891. [12] Another mount was made for the NMNH in the form of a mounted composite skeleton consisting of several specimens referred to S. stenops that were collected at Quarry 13 at Como Bluff in 1887, the most complete being USNM 6531. Four possible plate arrangements have been proposed over the years: After the end of the Bone Wars, many major institutions in the eastern United States were inspired by the depictions and finds by Marsh and Cope to assemble their own dinosaur fossil collections. Introduction to the Study of Dinosaurs. [45] Some have suggested that plates in stegosaurs were used to allow individuals to identify members of their species. Due to the fragmentary nature of most early Stegosaurus fossil finds, it took many years before reasonably accurate restorations of this dinosaur could be produced. Evolutionary scientists have recently claimed that pterosaurs had feathers. Some decorative bristles could work with Stegosaurus. 24-26 feet. [47], The vast majority of stegosaurian dinosaurs thus far recovered belong to the Stegosauridae, which lived in the later part of the Jurassic and early Cretaceous, and which were defined by Paul Sereno as all stegosaurians more closely related to Stegosaurus than to Huayangosaurus. (eds.). [32][33], Most of the information known about Stegosaurus comes from the remains of mature animals; more recently, though, juvenile remains of Stegosaurus have been found. Loss of feather coating would, by that theory, have been secondary, for instance in the case of the giant dinosaurs that could have become overheated. [68] He had changed his mind, however, by 1891, after considering the heavy build of the animal. The findings debunk the theory that feathers evolved . Since a cooling trend occurred towards the end of the Jurassic, a large ectothermic reptile might have used the increased surface area afforded by the plates to absorb radiation from the sun. [17] The argument has been a major one in the history of dinosaur reconstruction. That's when Stegosaurus was a species of dinosaur that walked around the Earth. However, this mount was dismantled in 1917 when the old Peabody Museum building was demolished. a. a keel bone (wishbone) c. a long tail b. teeth d. claw-bearing fingers . So from being sluggish "terrible lizards" with scales, cold blood and pea-brains that went extinct, dinosaurs are now understood to . Paleontologists had long thought that Stegosaurus had two parallel rows of plates, either staggered or paired, and that these afforded protection to the animals backbone and spinal cord. Of the species that have been classified in the upper Morrison Formation of the western US, only three are universally recognized: S. stenops, S. ungulatus and S. sulcatus. Flexible, armorlike scales protected the throat of Stegosaurus.. Bony plates. Which of the following features did Archaeopteryx not have? In 1910, Richard Swann Lull wrote that the alternating pattern seen in S. stenops was probably due to shifting of the skeleton after death. Did stegosaurus have feathers? . [39] Their teeth were "not tightly pressed together in a block for efficient grinding",[93] and no evidence in the fossil record of stegosaurians indicates use of gastrolithsthe stone(s) some dinosaurs (and some present-day bird species) ingestedto aid the grinding process, so how exactly Stegosaurus obtained and processed the amount of plant material required to sustain its size remains "poorly understood". While every effort has been made to follow citation style rules, there may be some discrepancies. All photos used are royalty-free, and credits are included in the Alt tag of each image. So did dinosaurs have big outer ears? Scientists believe they reproduced sexually, via mating, and laid eggs. There were three different species of Stegosaurus, but all were relatively similar looking. [49], Stegosaurus frequently is discovered in its own clade in Stegosauridae called Stegosauridae, usually including the taxa Wuerhosaurus and Loricatosaurus,[50] though Hesperosaurus is sometimes found in the group. Stegosaurus ungulatus by the describers. These are presumed to have served as defensive weapons, but they may have been ornamental. [70], Stegosaurus had short fore limbs in relation to its hind limbs. Unlike the sturdy jaws and grinding teeth common to its fellow ornithischians, Stegosaurus (and all stegosaurians) had small, peg-shaped teeth that have been observed with horizontal wear facets associated with tooth-food contact[92] and their unusual jaws were probably capable of only orthal (up-down) movements. . [2] Many of the plates are manifestly chiral[19][20] and no two plates of the same size and shape have been found for an individual; however plates have been correlated between individuals. [28] 2007 saw the description of a Stegosaurus specimen from the Upper Jurassic Lourinha Formation of Portugal, the specimen was placed as cf. Stegosaurus is a genus of armored dinosaur, with large bone plates along its neck, back and tail. Stegosaurus usually grew to a length of about 6.5 metres (21 feet), but some reached 9 metres (30 feet). Omissions? While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. Maidment, S. C. (2010). [101] Artist Charles R. Knight published his first illustration of Stegosaurus ungulatus based on Marsh's skeletal reconstruction in a November 1897 issue of The Century Magazine. Stegosaurus shared the land with a lot of other famous dinosaurs. [75] Christiansen and Tschopp (2010), having studied a well-preserved specimen of Hesperosaurus with skin impressions, concluded that the plates were covered in a keratin sheath which would have strengthened the plate as a whole and provided it with sharp cutting edges. Did stegosaurus have feathers? In some specimens of S. stenops, a caudal is also incorporated, as a caudosacral. The skull and dermal armour of, "A newly mounted skeleton of the armored dinosaur, Stegosaurus stenops, in the United States National Museum", Reconstructing an Icon: Historical Significance of the Peabodys Mounted Skeleton of, "Extinct Monsters: The Marsh Dinosaurs, Part II", "The Postcranial Skeleton of an Exceptionally Complete Individual of the Plated Dinosaur Stegosaurus stenops (Dinosauria: Thyreophora) from the Upper Jurassic Morrison Formation of Wyoming, U.S.A.", "Evidence for Sexual Dimorphism in the Plated Dinosaur Stegosaurus mjosi (Ornithischia, Stegosauria) from the Morrison Formation (Upper Jurassic) of Western USA". [40], A detailed computer analysis of the biomechanics of Stegosaurus's feeding behavior was performed in 2010, using two different three-dimensional models of Stegosaurus teeth given realistic physics and properties. Dinosaurs did have feathers ancestrally but most groups lost them. Did the Stegosaurus have teeth? Tooth wear and possible jaw action of. Aside from feathers, researchers. Stegosaurus, one of the many dinosaurs described in the Bone Wars, was first collected by Arthur Lakes and consisted of several caudal vertebrae, a dermal plate, and several additional postcranial elements that were collected north of Morrison, Colorado at Lakes YPM Quarry 5. Although they're sometimes called "flying dinosaurs," they are technically distinct from dinosaurs. if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[336,280],'animals_net-box-4','ezslot_5',115,'0','0'])};__ez_fad_position('div-gpt-ad-animals_net-box-4-0');We know they lived in areas that were semiarid, with a wet season and a dry season. This suggests that the different Stegosaurus species were relatively widespread. Colorful and scientifically accurate illustrations paired with intriguing facts will be sure to captivate your kids in grades 4-8. It had a short neck and a small head, meaning it most likely ate low-lying bushes and shrubs. all of these. . Scientists arent exactly sure how they chewed and foraged for food, because their mouth is simply, weird. A large, slow moving plant-eater, Stegosaurus would have defended itself from predators like Allosaurus and Ceratosaurus with its powerful spiked tail. Which basic group of dinosaur is this . They do estimate that they fed on a number of different plant types, including ferns, moss, fruits, cycads, conifers, and horsetails. Lucas reclassified this species in the new genus Hoplitosaurus later that year. Giant sauropods like Diplodocus and Camarasaurus, smaller herbivores like Camptosaurus, and predators including Allosaurus and Ceratosaurus. Browsing on a wide variety of plants would be essential. 25). Confirmed Stegosaurus remains have been found in the Morrison Formation's stratigraphic zones 26, with additional remains possibly referrable to Stegosaurus recovered from stratigraphic zone 1. It would be blatantly impossible to own one as a pet, even in theory. But T. rex didn't live until about 80 million years ago, up until about 65 million years ago in the great extinction event. [29][26], Sophie the Stegosaurus is the best preserved Stegosaurus specimen, being 85% intact and containing 360 bones. These creatures are most often encountered in herds, which are vicious enough as a group that only the most brazen predators dare attack them. The presence of feathers in raptorial dinosaurs cannot be denied. [5], At one time, stegosaurs were described as having a "second brain" in their hips. Up until a few years ago,. [102], Stegosaurus made its major public debut as a paper mache model commissioned by the U.S. National Museum of Natural History for the 1904 Louisiana Purchase Exposition. Did they have feathers too? The model was based on Knight's latest miniature with the double row of staggered plates,[12] and was exhibited in the United States Government Building at the exposition in St. Louis before being relocated to Portland, Oregon for the Lewis and Clark Centennial Exposition in 1905. But the paleontologist who first discovered a Stegosaurus fossil thought the plates laid flat on its back like a turtle's shell. However, it has some pretty oddly shaped teeth and jaws. Though it had not yet been completely prepared, the nearly complete and articulated type specimen of Stegosaurus stenops allowed Marsh to complete the first attempt at a reconstructed Stegosaurus skeleton. Today, it is generally agreed that their spiked tails were most likely used for defense against predators, while their plates may have been used primarily for display, and secondarily for thermoregulatory functions. Dinosaurs from Wuerho. It had passive defensive strategies like swinging its Stegosaurus tail for protection. This was supported by elongated vertebrae (bones that make up the spinal column). 2. Fossils of this dinosaur are actually relatively rare, and because of this we can only speculate the other habitats this creature lived in. Display and species recognition remain likely functions for the plates, although such hypotheses are difficult to investigate. How aggressive were they? Carnotaurus. [71][40] Tracks discovered by Matthew Mossbrucker (Morrison Natural History Museum, Colorado) suggest that Stegosaurus lived and traveled in multiple-age herds. Both groups evolved from a lineage of smaller armoured dinosaurs such as Scutellosaurus and Scelidosaurus of the Early Jurassic Period (206 million to 180 million years ago). [54], Susannah Maidment and colleagues in 2008 proposed extensive alterations to the taxonomy of Stegosaurus. Foster, J. [22] The Carnegie Museum in Pittsburgh on the other hand collected many Stegosaurus specimens, first at Freezout Hills in Carbon County, Wyoming in 190203. 560 pp. Feathers are what distinguishes birds from other existing lifeforms; but they're also what connects them to the creatures of yore. Based on this data, it is likely Stegosaurus also ate woodier, tougher plants such as cycads, perhaps even acting as a means of spreading cycad seeds. [2], The next species of Stegosaurus to be named was S. marshi by Frederick Lucas in 1901. [3] Though several more complete specimens have been attributed to Stegosaurus armatus, preparation of the bones and analysis has discovered that this type specimen is actually dubious, which is not an ideal situation for the type species of a well-known genus like Stegosaurus. The Stegosaurus is another famous dinosaur species that has captivated our imagination. The skeleton remained mounted until 1989 when the museum curator of the DMNS began a revision of the museum's fossil hall and dispatched an expedition to find additional Stegosaurus remains. It was a composite of several skeletons, primarily USNM 6531, with proportions designed to closely follow the S. stenops type specimen, which had been on display in relief nearby since 1918. Two years ago a study claimed to have found fossil evidence of "protofeathers . [41] Actual brain anatomy in Stegosaurus is poorly known, but the brain itself was small even for a dinosaur. Stegosaurus is famous for its two rows of kite-shaped plates that stick out from its neck, back, and tail. . Animals.NET aim to promote interest in nature and animals among children, as well as raise their awareness in conservation and environmental protection. . When it lived: Late Jurassic, 155-145 million years ago. A. pp. Two pairs of pointed bony spikes were present on the end of the tail. Ceratosaurus and Stegosaurus dinosaurs: Warm-blooded. The spinal cord in the region of the sacrum was enlarged and was actually larger than the brain, a fact that gave rise to the misconception that Stegosaurus possessed two brains. 'roof-lizard') is a genus of herbivorous, four-legged, armored dinosaur from the Late Jurassic, characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails. [99] Stegosaurus is commonly found at the same sites as Allosaurus, Apatosaurus, Camarasaurus, and Diplodocus. It had a very distinct and unusual posture. Determining the extent of this creatures range is difficult to do, because their fossils are somewhat rare. As the recently-described Yutyrannus shows, even 30-foot-long tyrannosaurs were fluffy. Lucas also re-examined the issue of the life appearance of Stegosaurus, coming to the conclusion that the plates were arranged in pairs in two rows along the back, arranged above the bases of the ribs. [30], The quadrupedal Stegosaurus is one of the most easily identifiable dinosaur genera, due to the distinctive double row of kite-shaped plates rising vertically along the rounded back and the two pairs of long spikes extending horizontally near the end of the tail. Stegosaurus skeleton. The only interactions between Stegosaurus and humans are in movies and television. Down feathers were found on a pterosaur, so the fibers most of them have are indeed true proto-feathers. Asked by: Kaia Halvorson. [24] The expedition was successful in finding a nearly complete Stegosaurus near the Kessler site by Bryan Small, whose name would become the namesake of the new site. The finding raises the possibility that the very earliest. Many dinosaurs may have been covered in elaborate feathers similar to those of modern-day birds, according to a study of new fossils. [91], Stegosaurus and related genera were herbivores. the favored book National Geographic Kids Ultimate Dinopedia Second Edition collections that we have. Various hypotheses have attempted to explain the arrangement and use of the plates. [79], The thermoregulation hypothesis has been seriously questioned, since other stegosaurs such as Kentrosaurus, had more low surface area spikes than plates, implying that cooling was not important enough to require specialized structural formations such as plates. These variations cast doubt on the hypothesis of a strong thermoregulatory function for the plates of Stegosaurus, because such structures were not optimized in all stegosaurs for collecting or releasing heat. B. Discoveries of articulated stegosaur armor show, at least in some species, these spikes protruded horizontally from the tail, not vertically as is often depicted. [26] It is a young adult of undetermined sex, 5.8m (19ft) long and 2.9m (9.5ft) tall. It is on display in the University of Wyoming Geological Museum. Almost all birds are flying creatures to some degree, and they all have wings. While the idea of cloning . Debate is raging about whether pterosaurs, flying reptiles that lived alongside the dinosaurs, had feathers or not. [95] Conversely, if Stegosaurus could have raised itself on two legs, as suggested by Bakker, then it could have browsed on vegetation and fruits quite high up, with adults being able to forage up to 6m (20ft) above the ground. [3] Marsh initially believed the remains were from an aquatic turtle-like animal, and the basis for its scientific name, 'roof(ed) lizard' was due to his early belief that the plates lay flat over the animal's back, overlapping like the shingles (tiles) on a roof. [2][56] In 2015, Maidment et al. Much of their notoriety comes from their odd, and intriguing, appearance. [88] One 2009 study of Stegosaurus specimens of various sizes found that the plates and spikes had delayed histological growth in comparison to the skeleton and when the dinosaur reached maturity, growth in the osteoderms may have increased. Did T Rexes Have Feather? [12] This historically significant specimen was re-mounted ahead of the opening of the new Peabody Museum building in 1925. The discovery of 150-million-year-old fossils in Siberia. Stegosaur track assemblage from Xinjiang, China, featuring the smallest known stegosaur record. The skull's low position suggests that Stegosaurus may have been a browser of low-growing vegetation. [94] One hypothesized feeding behavior strategy considers them to be low-level browsers, eating low-growing fruit of various nonflowering plants, as well as foliage. New Mexico Museum of Natural History and Science Bulletin, 36. In their case, it contains what is called the glycogen body, a structure whose function is not definitely known, but which is postulated to facilitate the supply of glycogen to the animal's nervous system. There were flat floodplains, savannas dominated by ferns and the occasional tree, and forests. We know Stegosaurus didn't live in herds, but was probably solitary or lived in small groups. 2.5 - 3 meters. A cranium (CM 12000) was also found by Carnegie crews, one of the few known. Sereno, P.C., 1998, "A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria". Bakker suggested in 1986 that the plates were covered in horn comparing the surface of the fossilized plates to the bony cores of horns in other animals known or thought to bear horns. [10][7] The skeleton was expertly unearthed by Felch, who first divided the skeleton into labeled blocks and prepared them separately. [25], The most recognizable features of Stegosaurus are its dermal plates, which consisted of between 17 and 22 separate plates and flat spines. The Stegosaurus flaunted an array of plates and spikes. Cool story have fun. The bony plates on Stegosaurus's back were set . [24][25] The "Small Quarry" Stegosaurus' articulation and completeness clarified the position of plates and spikes on the back of Stegosaurus and the position and size of the throat ossicles found earlier first by Felch with the Stegosaurus stenops holotype, though like the S. stenops type, the fossils were flattened in a "roadkill" condition. (In 1893, Richard Lydekker mistakenly re-published Marsh's drawing under the label Hypsirhophus. [36] Such an extensive beak was probably unique to Stegosaurus and some other advanced stegosaurids among ornithischians, which usually had beaks restricted to the jaw tips. 1,350 2,000 kg. [45] The plates' large size suggests that they may have served to increase the apparent height of the animal, either to intimidate enemies[7] or to impress other members of the same species in some form of sexual display. Oxford, Blackwell Publishing. 3-4.500 lbs. There were three different species of Stegosaurus, but all were relatively similar looking. Description of the Stegosaurus. "Stegosaurus!" "Tyrannosaurus!" The six of us Morphed, and appeared where Hatchasaurus is. [21][8] These remains haven't been described and were mounted in 1932, the mount being a composite primarily of specimens AMNH 650 & 470 from Bone Cabin Quarry. Did the T. rex live in the Mesozoic era? Additional support for this idea was a punctured tail vertebra of an Allosaurus into which a tail spike fits perfectly. University of Chicago Press. Martin, A.J. Toes. They walked on four short legs, had small heads, and long tails capped with defensive spines.if(typeof ez_ad_units != 'undefined'){ez_ad_units.push([[468,60],'animals_net-medrectangle-4','ezslot_3',121,'0','0'])};__ez_fad_position('div-gpt-ad-animals_net-medrectangle-4-0'); A line of flattened, plate-like spines ran down their backs. These creatures were large, and had incredibly small brains. This scenario has Stegosaurus foraging at most 1m above the ground. "Ready to roll!" I shouted. S. stenops preserves 46 caudal vertebrae, and up to 49, and along the series both the centrums and the neural spines become smaller, until the neural spines disappear at caudal 35. 'roof-lizard') is a genus of herbivorous, four-legged, armored dinosaur from the Late Jurassic, characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails. [12] The aging mount was dismantled in 2003 and replaced with a cast in an updated pose in 2004. (2007). Stegosaurus went extinct around 150 million years ago, and never lived while humans were on earth. Now!" Jason shouted, and our Dinozords appeared. The spikes were probably used as defense mechanisms, while it is . Ears are made of cartilage and skin, and these are soft tissues which typically do not preserve well in the fossil record. The lower jaw had flat downward and upward extensions that would have completely hidden the teeth when viewed from the side, and these probably supported a turtle-like beak in life. Stegosaurus was up to 30 feet (9.1 meters) long. Annotated catalogue of the dinosaurs (Reptilia, Archosauria) in the collections of Carnegie Museum of Natural History. In 1914, Charles Gilmore argued against Lull's interpretation, noting that several specimens of S. stenops, including the now-completely prepared holotype, preserved the plates in alternating rows near the peak of the back, and that there was no evidence of the plates having shifted relative to the body during fossilization. Other ornithischians included Camptosaurus, Gargoyleosaurus, Dryosaurus, Othnielosaurus and Drinker. [42], In Stegosaurus stenops there are 27 bones in the vertebral column anterior to the sacrum, a varying number of vertebrae in the sacrum, with four in most subadults, and around 46 caudal (tail) vertebrae. Stegosaurus walked on its toes, which were supported by thick, wedge-shaped pads.. Throat guard. However, new discoveries and reexamination of existing Stegosaurus specimens since the 1970s suggest that the plates alternated along the backbone, as no two plates from the same animal have exactly the same shape or size. However, it has also been suggested that the plates could have helped the animal increase heat absorption from the sun. The tail appears to have been held well clear of the ground, while the head of Stegosaurus was positioned relatively low down, probably no higher than 1m (3.3ft) above the ground. The remains of over 80 individual animals of this genus have been found. Scant evidence in the fossil record has never been definitive - until now, scientists say. [37][38] Other researchers have interpreted these ridges as modified versions of similar structures in other ornithischians which might have supported fleshy cheeks, rather than beaks. . Animal fossils discovered include bivalves, snails, ray-finned fishes, frogs, salamanders, turtles like Glyptops, sphenodonts, lizards, terrestrial and aquatic crocodylomorphs like Hoplosuchus, several species of pterosaurs such as Harpactognathus and Mesadactylus, numerous dinosaur species, and early mammals such as docodonts (like Docodon), multituberculates, symmetrodonts, and triconodonts. One species, Stegosaurus ungulatus, is one of the largest known of all the stegosaurians, reaching 7 metres (23ft) in length and 3.8 metric tons (4.2 short tons) in body mass, and some specimens indicate an even larger body size. [13] 1918 saw the completion of the second Stegosaurus mount, and the first depicting S. stenops. Though it is not always perfectly preserved, the acromion ridge is slightly larger than in Kentrosaurus. According to paleontologist and National Geographic grantee Jack Horner, it stands to reason that dinosaurs had similar courting behaviors as today's birds. These middle Triassic reptiles, dating from about 230 million years ago, included such important genera as Eoraptor, Herrerasaurus, and Staurikosaurus; as far as paleontologists can tell, these were the first true dinosaurs, only recently evolved from their archosaur predecessors. 10 besttroodon 5 yr. ago [85], S. stenops had four dermal spikes, each about 6090cm (2.03.0ft) long. [46] Galton (2019) interpreted plates of an armored dinosaur from the Lower Jurassic (Sinemurian-Pliensbachian) Lower Kota Formation of India as fossils of a member of Ankylosauria; the author argued that this finding indicates a probable early Early Jurassic origin for both Ankylosauria and its sister group Stegosauria. Did not have to worry about predation based on their size as long as they were adults and healthy. [13] These were highly modified osteoderms (bony-cored scales), similar to those seen in crocodiles and many lizards today. . Were the feathers part of a complex mating ritual, or a stepping stone in the evolution of flight? However, recent research re-examined this and concluded this species also had four. Asked by: Kaia Halvorson. An important discovery came in 1937 again at Garden Park by a high school teacher named Frank Kessler in while leading a nature hike. The Stegosaurus, an armored dinosaur with bony plates running along its backbone and ending in a giant spiked tail, had large space at the end of the spinal cord. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. The forelimbs were much shorter than the hind limbs, which gave the back a characteristically arched appearance. [82] However, Christiansen and Tschopp (2010) consider this unlikely, as stegosaur plates were covered in horn rather than skin.
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