Psittacosaurus - Knowledge (XXG)

111: 2808: 8107: 3888: 803: 4236: 3400: 1565: 8113: 4838: 1179: 821: 3994: 3798: 4106:. However, a 2013 paper pointed out that the adult specimen did not belong with the nest, its skull having no sedimentary connection to the main slab where the juveniles occurred, but had been glued onto it. This artificial association led to the inference that the skull belonged to an individual, possibly a "mother", that was providing parental care for the 34 juveniles—a claim that is unfounded. Furthermore, the adult was also shown to be six years old, whereas histological studies have shown 2289: 8663: 1030: 135: 4172: 2273: 2190: 3911:

shearing action. Unlike most ceratopsians, their beaks did not form curved tips, but were instead rounded and flattened. If the jaws were aligned, the beaks could be used to crop objects, but if the lower jaw was retracted so that the lower beak was inside the upper beak, the jaws may have served a nutcracking function. A nut- or seed-rich diet would also match well with the gastroliths often seen in well-preserved psittacosaur skeletons.

4066: 3920: 1417: 2103: 1886: 2454:, but instead arise from discrete cell populations that exhibit continuous growth. A 2016 study by Ji Qiang and colleagues was published in the Journal of Geology. Their conclusion was that these were actually highly modified scales because the morphology and anatomy did not resemble feathers. A darkened soft-tissue structure was also found near the jugal horn; this may represent a keratinous sheath or a skin flap. 2800: 2491: 8693: 2418: 3742: 4090: 8669: 1620:. However, in 2002 the original authors published new images of the fossil which seem to show teeth in the lower jaw that exhibit the bulbous vertical ridge characteristic of psittacosaurs. Other authors have also defended its validity, while some continue to regard it as dubious. Sereno (2010) proposed that the best assignment for the type material may be Ceratopsia 4351: 7396: 1748:, as well as a prominent bony protuberance, pointing outwards and downwards, on the maxilla of the upper jaw. The maxillary protuberance is also now missing. Other features originally used to distinguish the species have been recognised as the results of the deformation of the skull after fossilisation. Sereno (2010) remained unconvinced of its validity. 4017:(AMNH), which is only 11 to 13 centimetres (4–5 inches) long, with a skull 2.4 centimetres (0.94 in) in length. Another hatchling skull at the AMNH is only 4.6 centimetres (1.8 in) long. Both specimens are from Mongolia. Juveniles discovered in the Yixian Formation are approximately the same age as the larger AMNH specimen. 1590:, northeastern China. This species is known from four fossil skulls, one associated with some skeletal material, found in 1973 by Chinese scientists. The age of the Jiufotang in Liaoning is unknown, but in the neighbouring province of Inner Mongolia, it has been dated to about 110 Ma, in the Albian stage of the Early Cretaceous. 3902:

Psittacosaurs had self-sharpening teeth that would have been useful for cropping and slicing tough plant material. Unlike later ceratopsians, they did not have teeth suitable for grinding or chewing their food. Instead, they used gastroliths—stones swallowed to wear down food as it passed through the

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cloaca is comparable to those of crocodilians, with discrete lateral lips that converge anteriorly, giving the cloaca a v-shape anatomy. It also shows resemblance to that of birds, with the dorsal lobe being homologous to the birds' cloacal protuberance. A 2022 study of SMF R 4970 identified it as an

4086:. Another juvenile-only cluster shows that specimens of different ages grouped together. These juveniles may have associated together as a close knit, mixed-age herd either for protection, to enhance their foraging, or as putative helpers at the parental nest. There is no evidence for parental care. 3764:. Russell and Zhao (1996) believed "the small brain size of psittacosaurs implies a very restrictive behavioural repertoire relative to that of modern mammals of similar body size". However, the 2007 study dispelled this theory when it found the brain to be more advanced. There is generally negative 1549:

in which it was discovered. Several individuals of different ages were discovered in the early 1970s by Chinese paleontologists and described by Sereno and Zhao, although the holotype and most complete skeleton belonged to a juvenile. An adult skeleton was later discovered at a different locality in

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skeletons, closely associated with the skull of an adult. The juveniles, all approximately the same age, are intertwined in a group underneath the adult, although all 34 skulls are positioned above the mass of bodies, as they would have been in life. This suggests that the animals were alive at the

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was semi-aquatic, swimming with its tail like a crocodile, and paddling and kicking. They based their interpretation on evidence including: the lacustrine (lake) depositional setting of many specimens; the position of the nostrils and eyes; interpretations of the motions of the arms and legs; tails

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has determined the growth rate of these animals. The smallest specimens in the study were estimated at three years old and less than 1 kilogram (2.2 lb), while the largest were nine years old and weighed almost 20 kilograms (44 lb). This indicates relatively rapid growth compared to most

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found it necessary to dig depressions in the ground it may have used its hindlimbs instead. The forelimbs could be used for two-handed grasping of objects or scratching the body, but due to their extremely limited flexibility and reach, they could have only been used to grasp objects very close to

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are complex, virtually identical to all other vertebrates in structure but having an exceptional thickness of about forty layers. As the sections of dermis were collected from the abdomen, where the scales were eroded, the tissue may have assisted with the musculature of the stomach and intestines

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is named for the region it was found in 2001, and first described by Sereno, Zhao and Lin in 2010. It is known from a skull and partial articulated skeleton with gastroliths. Many other specimens either cannot be determined to belong to any particular species, or have not yet been assigned to one.

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standpoint, whereas extant species often have very similar skeletal morphology but differ in other ways which would not normally be preserved in the fossil record, such as behaviour, or colouration. Therefore, actual species diversity may be much higher than currently recognised in this and other

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was likely quadrupedal and eventually gained the ability to become bipedal as it evolved, with the young retaining the quadrupedal gait of the ancestor in question. These findings also lead to the hypothesis that many such dinosaur families may have evolved along this path at some point in their

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Unlike many other dinosaurs, psittacosaurs had akinetic skulls: that is to say, the upper and lower jaws each behaved as a single unit, without internal joints. The only joint was the jaw joint itself, and psittacosaurs could slide their lower jaws forward and backward on the joint, permitting a

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supply to the region. The pit is surrounded by a massive amount of swelling along the lower third of the bone. This large amount of bone deposited around the injury indicates that the animal survived for quite a while despite the injury and subsequent infection. As psittacosaurids were bipedal

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on its hind legs that connected to the base of the tail. Its large eyes indicate that it also likely had good vision, which would have been useful in finding food or avoiding predators. The authors pointed out that there might have been variation in coloration across the range of the animal,

2342:(upper) surface of the tail. These were confirmed by the authors, as well as an independent scientist, to not represent plant material. The bristle-like integumentary structures extend into the skin nearly to the vertebrae, and were likely circular or tubular before being preserved. Under 2648:

by a combination of 32 anatomical features, including six that are unique to the species. Most of these are skull details, but one unusual feature is the presence of 23 vertebrae between the skull and pelvis, unlike the 21 or 22 in the other species where the vertebrae are known.

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prefecture of the Inner Mongolia Autonomous Region. The type specimen is a nearly complete skeleton, including part of the skull. However, only the skull, lower jaw, and foot have been described. Three other specimens were referred to this species but remain undescribed. Like

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was probably secondarily bipedal. The infants' front limbs grew at faster rates than the hind limbs at between hatching and three years of age. At the age of between four and six years, arm growth slowed and leg growth accelerated as the animal became mature. At this stage,

2217:(eye socket) is only 40% of total skull length, shorter than any other known ornithischian. The lower jaws of psittacosaurs are characterised by a bulbous vertical ridge down the centre of each tooth. Both upper and lower jaws sport a pronounced beak, formed from the 2429:

to analyze the internal structure of the bristles. The highly cornified bristles were arranged in tight clusters of three to six individual bristles, with each bristle being filled with pulp. The authors considered the bristles as being most similar to the quills of

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Leshchinskiy, Sergei V.; Fayngertz, Alexei V.; Voronkevich, Alexei V.; Maschenko, E. N.; Averianov, Alexander O. (2000). "Preliminary results of the investigation of the Shestakovo localities of Early Cretaceous vertebrates". In Komarov, A. V. (ed.).

1001:, citing his previous study as naming both to be members of Psittacosauridae, and considering the separate status of Protiguanodontinae as uncertain. Further preparation of the skeleton of AMNH 6254 showed significant similarities in the skeletons of 1808:, near the village of Lujiatun. While this bed has been dated differently by different authors, from 128 Ma in the Barremian stage, to 125 Ma in the earliest Aptian, revised dating methods have shown them to be about 123 million years old. 4113:

A 2014 analysis of the same specimen supported the association and concluded that the proximity of the six-year-old specimen to the post-hatchlings may indicate post-hatchling cooperation, making the six-year-old specimen a possible caretaker.

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animal genera are represented by multiple species, suggesting that this may have been the case for extinct dinosaur genera as well, although most of these species may not have been preserved. In addition, most dinosaurs are known solely from

4315:, found in the lowest beds of the Yixian Formation. Over 200 specimens attributed to this genus have been recovered from these and other beds of the Yixian, the age of which is the subject of much debate. Although many early studies using 2731:, which differs from other species in which these bones are known. The type specimen has a skull length of 13.2 centimetres (5.2 in) and a femoral length of 13 centimetres (5.1 in), but is not fully grown. An adult 2369:

sp., from a different specimen. The skin remains could be observed by a natural cross-section to compare them to modern animals, showing that dinosaurian dermal layers evolved in parallel to those in many other large vertebrates. The

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species known at the time. It was distinguished from the other known species by a shorter and wider snout, and an overall smaller size at 675 mm (26.6 in). Yang also revised the classifications of the other species of

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Many later expeditions by various combinations of Mongolian, Russian, Chinese, American, Polish, Japanese, and Canadian paleontologists also recovered specimens from throughout Mongolia and northern China. In these areas,

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probably had complex behaviours, based on the proportions and relative size of the brain. It may have been active for short periods of time during the day and night, and had well-developed senses of smell and vision.

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Ivantsov, S. V.; Fayngerts, A. V.; Feofanova, O. A.; Vladimirova, O. N.; Slobodin, D. A. (2024). "Early Cretaceous continental sedimentatary environments, palaeogeography and biota of southeastern Western Siberia".

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are present, indicating the genus had an acute sense of smell. The size of these bulbs are comparable to large predatory theropods, although they likely evolved to avoid predators instead of to seek out prey. The

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that AMHN 6254 was the only good specimen that could be found at Oshih, with only one additional skull and jaws of an adult, and two hatchling skulls, having been found in a later revisit to the locality in 1923.

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Sawyer, Roger; Washington, Lynette; Salvatore, Brian; Glenn, Travis; Knapp, Loren (2003). "Origin of Archosaurian Integumentary Appendages:The Bristles of the Wild Turkey Beard Express Feather-Type B Keratins".

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Sereno, Paul C. (2000). "The fossil record, systematics and evolution of pachycephalosaurs and ceratopsians from Asia". In Benton, Michael J.; Shishkin, Mikhail A.; Unwin, David M.; Kurochkin, Evgeny N. (eds.).

1499:, which had originally been found in Mongolia. Fossils of more than twenty individuals have since been recovered, including several complete skulls and skeletons, making this the most well-known species after 4077:

individuals killed and buried by a volcanic mudflow indicates the presence of at least two age groups from two distinct clutches gathered together. This find has been taken as evidence for group fidelity and

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can be distinguished by numerous features of the jugals, which have very prominent 'horns'. It is also the smallest known species. One adult skull measures only 9.5 centimeters (3.75 in) in length.

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of Siberia, which ranges from the Barremian to Aptian stages of the Early Cretaceous. Individuals of this species could grow up to 2.5 meters in length, making it one of the largest members of the genus.

1431:, although only nine to eleven are considered valid today. This is the highest number of valid species currently assigned to any single non-avian dinosaur. In contrast, most other dinosaur genera are 1439:

is known from hundreds of fossil specimens, most other dinosaur species are known from far fewer, and many are represented by only a single specimen. With a very high sample size, the diversity of

1782:. The remains were not completely described until 2006. Two nearly complete, articulated skeletons and a variety of disarticulated material from other individuals of all ages are known from the 1127:

was found, and in 1948 they revisited the sites of the American expeditions and excavated fragmentary postcrania from Oshih and Ondai Sair. The material from these expeditions was taken to the

6561: 1351:, or approximately 125 to 100 mya. Fossil remains of over 75 individuals have been recovered, including nearly 20 complete skeletons with skulls. Individuals of all ages are known, from 1721: 1077: 764:

is one of the most completely known dinosaur genera. Fossils of hundreds of individuals have been collected so far, including many complete skeletons. Most age classes are represented, from

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Zhou, C. F.; Gao, K. Q.; Fox, R. C.; Du, X. K. (2007). "Endocranial morphology of psittacosaurs (Dinosauria: Ceratopsia) based on CT scans of new fossils from the Lower Cretaceous, China".

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Yang, W.; Li, S.; Jiang, B. (2007). "New evidence for Cretaceous age of the feathered dinosaurs of Liaoning: Zircon U-Pb SHRIMP dating of the Yixian Formation in Sihetun, northeast China".

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Fossil reptiles from Mongolia and Kansu. Reports from the Scientific Expedition to the North-western Provinces of China under Leadership of Dr. Sven Hedin. VI. Vertebrate Palaeontology 6.

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in 1983. Disarticulated postcranial remains representing multiple individuals were found at the same locality and were assigned to the species. While it differs from the type specimen of

2332:. Larger scales were arranged in irregular patterns, with numerous smaller scales occupying the spaces between them, similarly to skin impressions known from other ceratopsians, such as 2390:, likely related to living in a dense forest habitat with little light, much like many modern species of forest-dwelling deer and antelope; stripes and spots on the limbs may represent 2186:('hand'), as opposed to the five found in most other ornithischians (including all other ceratopsians), while the four-toed hindfoot is very similar to many other small ornithischians. 1720:

after the nearby mountain called Mazongshan (Horse Mane Mountain) and has been described in a preliminary manner. Unfortunately, the skull was damaged while in the care of the Chinese

3790:, whose EQ ranges from 0.30 to 0.38. Behaviours influenced by high EQs include nest-building, parental care, and bird-like sleeping, some of which have been shown to be present in 4082:

extending beyond the nest; the earliest such evidence for any ceratopsian. Even very young psittacosaur teeth appear worn, indicating they chewed their own food and may have been

1854:, named for the large size of its skull by Sereno, Zhao and two colleagues in 2007. You and colleagues described an additional specimen and concurred that it was distinct from 2045:. The vast majority of these have not been assigned to any published species, although many are very well preserved and some have already been partially described. Nearly 100 2461:, the first one known from a non-avian dinosaur. The positioning of the individual when it died is oriented obliquely, so the structure can be seen better in the right side. 1404:, it falls within the range of individual variation seen in other specimens of that species and is no longer recognised as a valid species. You and Dodson (2004) included 1393: 6726:

You, Hailu; Xu, Xing; Wang, Xiaolin (2003). "A new genus of Psittacosauridae (Dinosauria: Ornithopoda) and the origin and early evolution of marginocephalian dinosaurs".

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Eberth, David A.; Russell, Dale A.; Braman, D. R.; Deino, A. L. (1993). "The age of the dinosaur-bearing sediments at Tebch, Inner Mongolia, People's Republic of China".

2338:. A series of what appear to be hollow, tubular bristle-like structures, approximately 16 centimetres (6.3 in) long, were also preserved, arranged in a row down the 5501:

Wang, S; Hu, H; Li, P; Wang, Y (2001). "Further discussion on the geologic age of Sihetun vertebrate assemblage in western Liaoning, China: evidence from Ar-Ar dating".

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is 16.2 centimetres (6.4 in) in length. Other specimens are larger, with the largest documented femur measuring about 21 centimetres (8.25 in) long.

2245:(cheek) bones. There is still no sign of the bony neck frill or prominent facial horns which would develop in later ceratopsians. Bony horns protrude from the skull of 8912: 2608:. The skull of the type specimen is 20.7 centimetres long (8.25 in), and the femur is 22.3 cm (8.75 in) in length. It is also distinguished by its 4097:

In 2004, a specimen found in the Yixian Formation was claimed as evidence for parental care in dinosaurs. The specimen DNHM D2156 consists of 34 articulated juvenile

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had its umbilicus at least until sexual maturity. It is uncertain whether the umbilicus is present in mature or nearly mature individuals of all non-avian dinosaurs.

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digestive system. Sometimes numbering more than fifty, these stones are occasionally found in the abdominal cavities of psittacosaurs, and may have been stored in a

8786: 1616:. In 2000, Sereno questioned the validity of this species, citing its eroded and fragmentary nature, and noted an absence of features characteristic of the genus 8902: 2530:

is among the largest known species. The skull of the type specimen, which is probably a juvenile, is 15.2 centimetres (6 in) long, and the associated

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Andrews, R.C. (1932). "The New Conquest of Central Asia: A Narrative of the Explorations of the Central Asiatic Expeditions in Mongolia and China, 1921-1930".

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measures 19 cm (7.5 in) in length, while the largest-known skull is 20.5 centimetres (8 in) long, so this species was similar in size to

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is well known; a study on the anatomy and functionality of three specimens was published in 2007. Until the study, it was generally thought the brain of

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Vinther, Jakob; Nicholls, Robert; Lautenschlager, Stephan; Pittman, Michael; Kaye, Thomas G.; Rayfield, Emily; Mayr, Gerald; Cuthill, Innes C. (2016).

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Vinther, Jakob; Nicholls, Robert; Lautenschlager, Stephen; Pittman, Michael; Kaye, Thomas G.; Rayfield, Emily; Mayr, Gerard; Cuthill, Innes C. (2016).

4163:, the fibula is not a weight-bearing bone, so this animal would still have been able to walk to some extent. The source of the injury remains unknown. 4628:

Rozhdestvensky, A.K. (1955). "Novyye dannyye o psittakozavrakh – melovykh ornitopodakh" [New data on psittacosaurs — Cretaceous ornithopods].

2317:, China. The specimen, which is not yet assigned to any particular species, was likely illegally exported from China and was purchased in 2001 by the 5891:

Mayr, Gerald; Peters, Plodowski; Stephan, D.; Gerhard; Vogel, Olaf (2002). "Bristle-like integumentary structures at the tail of the horned dinosaur

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was distinguished by Zhao by having the shortest skull of all species, vertebral and tooth counts, and various features of the skull and skeleton.

110: 3780:. A higher EQ correlates with more complex behaviour, and various dinosaurs have high EQs, similar to birds, which range from 0.36 to 2.98. Thus, 2478:). Because the specimen is close to sexual maturity, it is likely that the umbilicus probably retained throughout this individual's life and that 3943:

species) were too short (only about 58% as long as the hindlimbs) to reach the ground, and their range of motion indicates they could neither be

1366:, but noted it was tentative because of the presence of multiple valid psittacosaur species in Inner Mongolia. Young also described the species 8917: 8897: 3418:

have been named, their relationships to each other have not yet been fully explored and no scientific consensus exists on the subject. Several

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itself was probably not directly ancestral to any other groups of ceratopsians. All other ceratopsians retained the fifth digit of the hand, a

946:, a general dissimilarity in the skeletons, and wide geographic separation of the two specimens, Gregory suggested in correspondence that the 8106: 6971: 3871:(and with the bristles on the tail interpreted as possibly skin-covered, forming a fin), providing a propulsive surface; and the presence of 3956:

the belly or sides of the animal and could have scratched only the belly, flank and knees. Even though the hands could not reach the mouth,

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in 2000 in a scientific paper written by five Russian paleontologists, but credit for the name is officially given to two of those authors,

7428: 906:. Osborn demonstrated the taxon was unique based on the short and deep snout, and the broad rear skull, as well as by lacking teeth in the 695:

at adulthood, with a high skull and a robust beak. One individual was found preserved with long filaments on the tail, similar to those of

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was unable to breed until it reached ten years of age. It is also unlikely that a single female would have so many offspring at one time.

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was entirely bipedal. The forelimbs were also too short to be used in digging or bringing food to the mouth, and Senter suggested that if

2675:(eye socket) is roughly triangular, and there is a prominent flange on the lower edge of the dentary, a feature also seen in specimens of 122: 4339:, suggests that the lower beds are younger, approximately 123.2 mya, while agreeing with an age of 122 mya for the upper beds. 879:

of a dinosaur, which was given the nickname of "Red Mesa skeleton". The location of discovery is also known as the Oshih locality of the

2807: 5352:"Biostratigraphy and palaeoenvironment of the dinosaur-bearing sediments in Lower Cretaceous of Mazongshan area, Gansu Province, China" 8112: 5452:

Skutschas PP, Morozov SS, Averianov AO, Leshchinskiy SV, Ivantsov SV, Fayngerts AV, Feofanova OA, Vladimirova ON, Slobodin DA (2021).

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name for Inner Mongolia. It is based on a nearly complete fossil skeleton, including most of the skull, found in the Early Cretaceous

848: 814: 1744:. However, more recent authors have noted that it can be distinguished by its proportionally long snout compared to other species of 8872: 6039: 4935: 4902: 4783: 4709: 1306: 622: 1770:. Two other nearby localities were explored in the 1990s, one of which produced several complete skeletons. This species was named 1674:, this species was discovered in the Eijnhoro Formation. Sereno (2010) found the species as described to be indistinguishable from 2358:

dinosaurs". However, they found that all other feather-like integument from the Yixian Formation could be identified as feathers.

8686: 4369: 5856:(Dinosauria: Ceratopsia) specimen from the Yixian Formation of western Liaoning, China: the first pathological psittacosaurid". 5950: 5181:

Averianov, Alexander O.; Voronkevich, Alexei V.; Leshchinskiy, Sergei V.; Fayngertz, Alexei V. (2006). "A ceratopsian dinosaur

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has been described from Mongolia so far, these specimens are still in preparation and have not yet been assigned to a species.

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and three Chinese and Canadian colleagues, is one of the oldest-known species, based on four skulls from the lower beds of the

2880:. The below cladogram is from their analysis, placing the genus as one of the most primitive ceratopsians. The authors (Farke 930:, AMNH 6253, included a nearly complete skeleton found articulated, and partial remains of the skull. While Osborn considered 8877: 7200:

Hedrick, B. P.; Gao Chunling; Omar, G. I.; Zhang Fengjiao; Shen Caizhi; Dodson, P. (2014). "The osteology and taphonomy of a

4042: 1435:, containing only a single known species. The difference is most likely due to artifacts of the fossilisation process. While 2655:

is distinguished by a prominent jugal 'horn' that is flattened on the front end, as well as some features of the teeth. The

2628:. The jugal has extremely prominent 'horns' and may contact the premaxilla, both features also seen in the possibly related 1862:

was originally characterised by a proportionately large skull, which was 39% of the length of its torso, compared to 30% in

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Xu, Xing; Zhao, Xijin (1999). "Psittacosaur fossils and their stratigraphical implications". In Wang, Y.; Deng, T. (eds.).

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is the number of 'horns' around the eyes, with three prominences on each postorbital, and one in front of each eye, on the

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in the formation to about 128 mya, and the highest to approximately 122 mya. A more recent Chinese study, using

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is readily distinguished from all other species by numerous features of the skull. Adult skulls are smaller than those of

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less than 13 centimetres (5.1 in) long, to very old adults reaching nearly 2 metres (6 ft 7 in) in length.

1866:, and other features. However, a 2013 study utilising morphometric analysis showed that the supposed differences between 134: 8892: 8887: 8862: 8857: 8847: 8662: 6232:"A unique cross section through the skin of the dinosaur Psittacosaurus from China showing a complex fibre architecture" 4692:

You, Hailu; Dodson, Peter (2004). "Basal Ceratopsia". In Weishampel, David B.; Dodson, Peter; Osmolska, Halszka (eds.).

2054: 1572: 1013:, and other details of the skull and skeleton. Osborn also referred the specimen AMNH 6261 from the Oshih Formation to 3887: 1443:

can be analysed more completely than that of most dinosaur genera, resulting in the recognition of more species. Most

802: 3971:, ranging in age from less than a year old to ten-year-old adults, Qi Zhao from the University of Bristol found that 1461:

are primarily distinguished by features of the skull and teeth. Several species can be recognised by features of the

4235: 2568:. Because of the flared cheeks, the skull is actually wider than it is long. A smaller 'horn' is present behind the 3967:

may not have been entirely bipedal for its entire lifespan. Taking sections from the limb bones of 16 specimens of

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skeletons were excavated in Mongolia during the summers of 2005 and 2006 by a team led by Mongolian paleontologist

6820:"A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia" 1874:

were due to differences in preservation and crushing. The study concluded that both represented a single species.

1205:. Of this material, the nearly complete skeleton and skull IVPP V738 was described as the type of the new species 8867: 4492:

Sereno, Paul C. (2010). "Taxonomy, cranial morphology, and relationships of parrot-beaked dinosaurs (Ceratopsia:

2450:; these structures differ from feathers in that they are unbranched, heavily cornified and do not develop from a 2233:

material. As the generic name suggests, the short skull and beak superficially resemble those of modern parrots.

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postcranial skeletons are more typical of a 'generic' bipedal ornithischian. There are only four digits on the

1725: 1701: 1564: 554: 443: 7175: 5573:"Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics" 4336: 6907:

Schmitz, L.; Motani, R. (2011). "Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology".

6418: 5735:"A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull" 4215:

mammal swallowed its prey in large chunks. This specimen is notable in that it is the first-known example of

2771:. Overall, this species is thought to exhibit several primitive characteristics compared to other species of 2126:—can reach 2 metres (6.5 ft) in length. The maximum adult body weight was most likely over 20 7637: 4246: 2711:, although it is less pronounced than in those species. The material appears to be roughly the same size as 2590:, seen in other species, and the entire lower jaw is bowed outwards, giving the animal the appearance of an 1728:, which have not been precisely dated, although there is some evidence that they were deposited in the late 1081: 1056:

described two additional species in 1932. Known from a crushed skull and fragmentary lower jaw, Young named

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In 2014, the describers of a new taxon of basal ceratopsian published a phylogenetic analysis encompassing

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approximately 6–7 year old subadult by comparing its femoral length to that of similarly-aged specimens of

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is basal to all other species. This would be consistent with its earlier appearance in the fossil record.

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is known from hundreds of individual specimens, of which over 75 have been assigned to the type species,

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by "significant, but structurally minor, details." These include the presence of a pyramidal horn on the

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depending on differences in the light environment. The authors were unable to determine which species of

2350:. The study stated that, "at present, there is no convincing evidence which shows these structures to be 1779: 1088:, and fragments of vertebrae and limbs were found in the same locality, with the tooth being referred to 460: 8882: 8812: 8696: 7546: 4054: 3829:, with one individual preserving them likely contracted postmortem, but if they are similar to those of 2826: 2391: 2058: 1775: 1724:(IVPP), and several fragments have been lost, including all of the teeth. The remains were found in the 1242:

would have the same species name. Contrasting Rozhdestvensky, Yang retained the earlier Chinese species

8668: 2691:. The complete type skull, probably adult, is 13.7 centimetres (5.5 in) long. The dentary of 2288: 1321:, but separated them to bring the count of members of Psittacosauridae to one genus and five species. 8760: 7343: 7255: 7213: 7075: 7019: 6916: 6831: 6735: 6598: 6577: 6560:

Mayr, Gerald; Pittman, Michael; Saitta, Evan; Kaye, Thomas G.; Vinther, Jakob; Benson, Roger (2016).

6507: 6453: 6344: 6295: 6168: 5904: 5865: 5803: 5643: 5584: 5532: 5426: 5366: 5254: 5194: 5091: 5048: 5004: 4224: 4177: 2659:, one of the three bones of the pelvis, also bears a characteristically long bony process behind the 2394:. The specimen also had dense clusters of pigment on its shoulders, face (possibly for display), and 2250: 1609: 1453: 1298: 1190: 1152: 1116: 1112: 1097: 1018: 998: 919: 903: 895: 840: 5403:

Materials of the Regional Conference of the Geologists of Siberia, Far East and North East of Russia

4211:

in its abdominal cavity. Several of the juvenile's bones are still articulated, indicating that the

1850:

from the same lower beds of the Yixian Formation had previously been classified in its own species,

8751: 7802: 7414: 7378: 6031: 4927: 4364: 3840: 2853: 2723:

is distinctly narrow compared to that of other species, resulting in a narrower skull overall. The

2612:, which is longer than any other species, at 15 to 18% of skull length. A very striking feature of 2503: 2262: 2209:

dinosaurs of its time. Extremely tall in height and short in length, the skull has an almost round

2050: 1957:

in 2003. Sereno (2010) regarded its distinct proportions as due to crushing and compression of the

1801: 1605: 1583: 1022: 395: 5453: 2442:. Similar, non-feather-derived bristles are found in a few extant birds such as the "horn" on the 2325:. It was described while awaiting repatriation; previous repatriation attempts were unsuccessful. 1954: 1378:. You and Dodson (2004) followed this in a table, but Sereno regarded both species as synonyms of 558: 480: 8522: 8472: 7904: 7298: 7279: 7091: 6988: 6940: 6751: 6603: 6192: 6001: 5928: 5827: 5710: 5659: 5548: 5480: 5382: 5210: 5147:

Buffetaut & Suteethorn, 1992, a ceratopsian dinosaur from the Lower Cretaceous of Thailand".

5064: 5039:(Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northeastern China". 4995:(Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northwestern China". 4316: 4273: 3408: 2915: 2625: 2586: 2451: 2351: 2318: 2279: 2042: 2037:

sp., although it is not assumed that they belong to the same species. More than 200 specimens of

1966: 1942: 1658: 1480: 1202: 1045: 983: 880: 527: 129: 7140: 4130:. The specimen in question, consisting of a complete adult skeleton and tentatively assigned to 3427: 2663:(hip socket). An adult femur has a published length of about 16 centimetres (6.3 in). 2398:(which may have had an antimicrobial function, though this has been disputed), as well as large 8817: 7400: 5634:(Dinosauria: Psittacosauridae) from the Lower Cretaceous of Western Liaoning Province, China". 4894: 4819: 4775: 4701: 4389: 1950: 1029: 550: 8799: 8791: 8605: 8543: 8506: 7980: 7867: 7271: 7037: 6967: 6932: 6859: 6800: 6654: 6523: 6479: 6370: 6313: 6261: 6184: 6035: 5920: 5819: 5764: 5612: 4931: 4898: 4779: 4705: 4293: 4171: 4079: 3868: 3280: 2885: 2343: 2314: 1578:

A second species described in 1988 by Sereno and Zhao, along with two Chinese colleagues, was

1374:. It is based on several skull fragments. He later synonymised the two species under the name 1348: 664: 8804: 6771:"A basal ceratopsian with transitional features from the Late Jurassic of northwestern China" 2825:

of the family Psittacosauridae, which was also named by Osborn in 1923. Psittacosaurids were

8635: 8433: 8258: 7960: 7655: 7370: 7351: 7263: 7221: 7155: 7118: 7083: 7027: 6924: 6889: 6849: 6839: 6790: 6782: 6743: 6708: 6644: 6634: 6593: 6585: 6515: 6469: 6461: 6360: 6352: 6303: 6251: 6243: 6176: 6103: 6073: 6023: 5993: 5985: 5912: 5873: 5811: 5754: 5746: 5700: 5651: 5602: 5592: 5540: 5472: 5434: 5374: 5332: 5262: 5202: 5099: 5056: 5012: 4973: 4919: 4886: 4767: 4693: 4544: 4417: 4356: 4265: 2836: 2763:. The jugal bones flare outwards widely, making the skull wider than it is long, as seen in 2617: 2339: 2310: 2189: 1926: 1906: 1805: 1654: 1213:. Yang also assigned 11 other specimens to the taxon, considering it to be the most diverse 963: 884: 578: 30: 5120:

Buffetaut, Eric; Suteethorn, Varavudh (1992). "A new species of the ornithischian dinosaur

4866:

Proceedings of the Seventh Annual Meeting of the Chinese Society of Vertebrate Paleontology

2272: 1977:. He did not synonymise the two species because of difficulties with the holotype skull of 8529: 8481: 8440: 8376: 8279: 8230: 7932: 7856: 7811: 7685: 7671: 7630: 7504: 7488: 5681: 4548: 4320: 4065: 3919: 3224: 2980: 2905: 2865:

of Psittacosauridae, but is still found in most other ceratopsians and in fact most other

2779:

was small-bodied (one metre (3 ft 3 in) long) and differs from other species of

2672: 2502:

are flat on top, especially over the back of the skull, with a triangular depression, the

2443: 2329: 2241:

ceratopsians, such as the unique rostral bone at the tip of the upper jaw, and the flared

2214: 2183: 1767: 1763: 1507:

named a new species after his mentor, C. C. Young, in 1962. However, the type specimen of

1432: 1416: 864: 227: 7371: 6024: 6022:

Sereno, P. C. (1997). "Psittacosauridae". In Currie, Philip J.; Padian, Kevin P. (eds.).

4920: 3847:

show that the genus was much more agile than later ceratopsians. Comparisons between the

7347: 7259: 7217: 7122: 7079: 7023: 6920: 6835: 6739: 6581: 6511: 6457: 6348: 6299: 6172: 5908: 5869: 5807: 5787:

Qingjin, Meng; Jinyuan, Liu; Varrichio, David J.; Huang, Timothy; Chunling, Gao (2004).

5647: 5588: 5536: 5430: 5370: 5258: 5198: 5095: 5052: 5008: 8536: 8495: 8426: 8413: 8384: 8369: 8339: 8300: 8286: 8203: 8164: 8043: 7953: 7918: 7911: 7791: 7741: 7664: 6854: 6819: 6795: 6770: 6747: 6712: 6649: 6622: 6542: 6474: 6441: 6365: 6332: 6256: 6231: 6077: 5978:, a new species of ceratopsian dinosaur from the Ondai Sayr locality, central Mongolia" 5759: 5734: 5655: 5607: 5572: 5321:(Dinosauria: Ceratopsia) from the Early Cretaceous Yixian Formation, Liaoning, China". 5185:

from the Early Cretaceous of West Siberia, Russia and its phylogenetic relationships".

4156: 4102:

time of burial, which must have been extremely rapid, perhaps due to the collapse of a

3848: 3825:

in reptiles directly show the size of the eyeball. The rings are not well preserved in

3822: 3817: 3150: 2997: 2553: 2387: 2007:

is the oldest available name, the researchers argued that because the type specimen of

1929:

of northeastern China, who lived in the same general area in which the fossil skull of

1885: 1783: 1713: 1622: 1601: 1262:. Following his new breakdown of species, Yang described the distribution of the genus 1209:, which was found in a red layer 10 mi (16 km) northwest of Rongyang City in 1168: 1123:. In 1946 they discovered a new locality, Ulan Osh, where a disarticulated specimen of 1068:, was named for partial lower jaws and teeth, which Young only tentatively referred to 1061: 1053: 1049: 979: 729: 391: 335: 211: 7240: 7056: 6149: 5788: 5351: 2799: 2490: 2382:

As described in a 2016 study, examination of melanosomes preserved in the specimen of

910:. In the same paper, Osborn also described another new taxon he considered similar to 902:, describing its parrot-like beak on the suggestion of fellow American paleontologist 867:

of the Artsa Bogdo Basin, Wong, the Mongolian chauffeur, discovered a nearly complete

8836: 8614: 8593: 8563: 8554: 8454: 8348: 8293: 8272: 8244: 8237: 8223: 8216: 8022: 8011: 8004: 7946: 7939: 7925: 7883: 7818: 7784: 7755: 7708: 7095: 7087: 6107: 6005: 5663: 5552: 5484: 5068: 4887: 4768: 4694: 4585: 4135: 3980:

would switch to a bipedal stance. These findings further reveal that the ancestor of

3856: 3831: 3786: 3768:

for brain size with development in vertebrates, but this was shown not to be true in

3419: 3257: 3207: 3081: 2869:. It is considered highly unlikely that the fifth digit or antorbital fenestra would 2447: 2438: 2346:, they gave off the same fluorescence as scales, providing the possibility they were 1918: 1101: 959: 955: 780: 747: 733: 68: 7002:

Zhao, Qi; Benton, Michael J.; Sullivan, Corwin; Sander, P. Martin; Xu, Xing (2013).

6964:

New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium

6944: 6755: 6607: 6196: 5932: 5714: 5317:

Changfu, Zhou; Keqin, Gao; Fox, Richard C.; Shuihua, Chen (2006). "A new species of

5214: 4918:

Archibald, J. David. (1997). "Species". In Currie, Philip J.; Padian, Kevin (eds.).

4498:

New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium

3960:

could have still used them to carry nesting material or food to a desired location.

3741: 2417: 2102: 8628: 8579: 8572: 8488: 8461: 8447: 8355: 8328: 8321: 8314: 8265: 8251: 8143: 8130: 8061: 8050: 8035: 7997: 7989: 7971: 7876: 7842: 7825: 7777: 7770: 7726: 7531: 7479: 7283: 5831: 5386: 5245:

Russell, D. A.; Zhao, X. (1996). "New psittacosaur occurrences in Inner Mongolia".

5060: 5016: 4535:

Young, C. C. (1931). "On some new dinosaurs from western Suiyuan, Inner Mongolia".

4089: 3295: 3167: 3095: 2889: 2844: 2716: 2656: 2334: 2238: 2206: 1987: 1934: 1646: 1551: 1444: 1388: 1344: 1293:

Further discoveries in the Qingshan Formation of Laiyang in 1958 were described by

1143:

also discovered a partial skull and skeleton of multiple individuals referrable to

971: 773: 412: 289: 195: 7355: 7225: 5973: 5877: 5544: 2552:(cheek) bone on the outside of the skull. The jugals flare out sideways, forming ' 1897:

A third species of Lujiatun psittacosaur, the first to be named, was described as

7204:

bonebed assemblage of the Yixian Formation (Lower Cretaceous), Liaoning, China".

6893: 6844: 5597: 5336: 4960:

Brinkman, D. B.; Eberth, D. A.; Ryan, M. J.; Chen, P. (2001). "The occurrence of

4272:

to northern China, and possibly as far south as Thailand. The most common age of

2514:(the tooth-bearing bone of the lower jaw), although it is not as prominent as in 1995:. Sereno's hypothesis was supported by a morphometric study in 2013, which found 8745: 8621: 8515: 8398: 8362: 8185: 7897: 7762: 5350:

Tang, F.; Luo, Z.; Zhou, Z.; You, H.; Georgi, J. A.; Tang, Z.; Wang, X. (2001).

5323: 4496:)". In Ryan, Michael J.; Chinnery-Allgeier, Brenda J.; Eberth, David A. (eds.). 4297: 4204: 4199: 3895: 3872: 3431: 2784: 2573: 2404: 1538: 1457:

dinosaur genera. As some species are known only from skull material, species of

1330: 714: 352: 43: 6962:". In Ryan, Michael J.; Chinnery-Allgeier, Brenda J.; Eberth, David A. (eds.). 6639: 4300:

formations of this age in Mongolia and northern China have produced fossils of

2436:, and the sparsely distributed elongated broad filamentous feathers (EBFFs) of 2309:

is known from a Chinese specimen, SMF R 4970, which most likely comes from the

2086:

in 2019 from a complete skull and partial skeleton. recovered in the Barremian

1519:

is generally considered a junior synonym of that better-known species. As with

8391: 8307: 8157: 7890: 7678: 7612: 7599: 7558: 7437: 6465: 6356: 6308: 6283: 6180: 5916: 5852:

Lü, Junchang; Kobayashi, Yoshitsugu; Lee, Yuong-Nam; Ji, Qiang (2007). "A new

5206: 4346: 4289: 2935: 2922: 2822: 2668: 2660: 2609: 2545: 2432: 2410:

the specimen belonged to due to the way the skull is preserved, but ruled out

2302: 2127: 1666: 1527:, You and Dodson (2004) listed it as valid in a table, but not in their text. 1504: 1294: 939: 907: 852: 832: 697: 656: 649: 373: 243: 88: 53: 8736: 7004:"Histology and postural change during the growth of the ceratopsian dinosaur 5972:

Napoli, James G.; Hunt, Tyler; Erickson, Gregory M.; Norell, Mark A. (2019).

4134:, was found in the lower beds of the Yixian Formation. There is no sign of a 2839:. While Psittacosauridae was an early branch of the ceratopsian family tree, 6966:. Bloomington and Indianapolis: Indiana University Press. pp. 328–339. 6928: 4571:

from the Lower Cretaceous of Asia and the relationships of the Ceratopsia".

4281: 4241: 4212: 4139: 4127: 4083: 4038: 4030: 4021: 3765: 2870: 2866: 2862: 2591: 2041:

have been found in the Yixian Formation, which is famous for its fossils of

1729: 1352: 1010: 784: 765: 146: 93: 37: 7299:"Juvenile-only clusters and the behaviour of the Early Cretaceous dinosaur 7275: 7041: 6936: 6863: 6804: 6786: 6658: 6527: 6483: 6374: 6317: 6265: 6247: 6218: 6188: 5924: 5823: 5768: 5750: 5616: 5476: 5378: 5287:

sp. nov.) from Mazongshan area, Gansu Province, China". In Dong, Z. (ed.).

4730:

Coombs, Walter P (1982). "Juvenile specimens of the ornithischian dinosaur

1949:

the specimen. Genus and species were both named by Chinese paleontologists

1309:. Known for a complete skull, partial vertebral series and partial pelvis, 7395: 7176:"Paleontologists describe a possible dinosaur nest and young 'babysitter'" 7160: 6699:

Osborn (Ceratopsia: Psittacosauridae) inferred from long bone histology".

6150:"Bristle-like integumentary structures at the tail of the horned dinosaur 6064:

Osborn (Ceratopsia: Psittacosauridae) inferred from long bone histology".

5705: 5438: 2210: 8730: 8192: 8178: 8171: 7734: 7470: 7461: 6129: 6094:

Senter, P (2007). "Analysis of forelimb function in basal ceratopsians".

4500:. Bloomington and Indianapolis: Indiana University Press. pp. 21–58. 4216: 4147: 3944: 3813: 3119: 2894: 2581: 2474:(belly button) known from a non-avian dinosaur (the oldest known from an 2399: 2371: 2355: 2225:

bones, respectively. The bony core of the beak may have been sheathed in

2091: 1709: 1587: 1546: 1484: 1210: 1136: 1033: 923: 876: 872: 860: 856: 806: 791: 742: 684: 676: 652: 179: 166: 83: 78: 63: 58: 48: 7267: 6958:

Ford, Tracy L.; Martin, Larry D. (2010). "A semi-aquatic life habit for

4159:

bone in the leg would most likely have been fatal. Unlike the femur and

1836:

separate species due to the inadequacies of the latter's type specimen.

1408:

in a table of valid taxa, but did not include it as such in their text.

671:-rich non-avian dinosaur genus. Up to 12 species are known, from across 8778: 8586: 7748: 7692: 7141:"Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur 7057:"Social behaviour and mass mortality in the basal ceratopsian dinosaur 7032: 7003: 6623:"Oldest preserved umbilical scar reveals dinosaurs had 'belly buttons'" 6589: 4412:

Osborn, Henry F. (1923). "Two Lower Cretaceous dinosaurs of Mongolia".

4332: 4269: 3904: 2949: 2858: 2831: 2787:, a depression on the postorbital-jugal contact, and enamel thickness. 2724: 2511: 2507: 2475: 2347: 2322: 2226: 2062: 1946: 1488: 1333: 1194: 1140: 776: 720: 668: 646: 98: 73: 6390:"Scientists reveal most accurate depiction of a dinosaur ever created" 5035:

Sereno, Paul C.; Xijin, Zhao; Zhengwu, Chang; Chenggang, Rao (1988). "

4323:, tens of millions of years outside of the expected temporal range of 3939:

concluded that the forelimbs of these taxa (and likely those of other

3875:, interpreted as ballast. They further suggested that some species of 3843:

is related to the agility of reptiles, and the large curved canals in

1816:, which was found in the same beds. It is potentially synonymous with 1017:, so the teeth of the two taxa could be compared. It was mentioned in 7455: 6769:

Xing, Xu; Forster, Catherine A.; Clark, James M.; Mo, Jinyou (2006).

6519: 6209:

Buffetaut, Eric (2001). Tantalizing glimpse of a vanishing dinosaur.

5997: 4820:"New psittacosaurid highlights skull enlargement in horned dinosaurs" 4422: 4304:, leading to the definition of this time period in the region as the 4285: 4227:, the production of more numerous offspring to counteract this loss. 4189:

Another fossil from the Yixian Formation provides direct evidence of

4143: 4103: 4046: 2458: 2395: 2362: 1740:, with no unique features that separate it from any other species of 1462: 1341: 1337: 1132: 891: 887: 692: 680: 638: 635: 156: 8707: 6695:

Erickson, Gregory M.; Tumanova, Tatyana A. (2000). "Growth curve of

5815: 5266: 5103: 4977: 3422:

analyses have been published, with the most detailed being those by

2122:

and skeleton, but share the same overall body shape. The best-known—

6818:

Farke, A. A.; Maxwell, W. D.; Cifelli, R. L.; Wedel, M. J. (2014).

5989: 5454:"Femoral histology and growth patterns of the ceratopsian dinosaur 4700:(2nd ed.). Berkeley: University of California Press. pp. 2361:

In 2008, another study was published describing the integument and

2278:

Specimen with preserved tail integument and pigmentation (specimen

1511:(a partial skeleton and skull) was discovered in the same rocks as 1222:. Following similar conclusions to Rozhdestvensky, Yang considered 732:

of the latter and an early offshoot of the branch that led to more

724:. Once in its own family, Psittacosauridae, with other genera like 4964:

Sereno and Chow, 1988 in the Urho area, Junggar basin, Xinjiang".

4609:

Young, C. C. (1958). "The dinosaur remains of Laiyang, Shantung".

4234: 4170: 4160: 4151: 4088: 4064: 3992: 3918: 3886: 3796: 3740: 3398: 2806: 2798: 2728: 2549: 2531: 2510:(an upper jaw bone). A flange is present on the lower edge of the 2489: 2471: 2416: 2242: 2230: 2188: 2119: 2101: 2011:

was better preserved, the correct name for this species should be

1884: 1563: 1415: 1177: 1028: 868: 819: 801: 672: 642: 6989:"How 'parrot dinosaur' switched from four feet to two as it grew" 6120:

Dalton, Rex (2001). Wandering Chinese fossil turns up at museum.

5571:

Hedrick, B. P.; Dodson, P. (2013). Evans, Alistair Robert (ed.).

4388:

Colbert, Edwin H. (Edwin Harris); Knight, Charles Robert (1951).

4288:

stages of the Early Cretaceous, or approximately 125 to 105

3839:

would have had large eyes and acute vision. The curvature of the

2671:

of any species, making the skull nearly circular in profile. The

1758:

Beginning in the 1950s, Russian paleontologists began excavating

1608:, described a partial upper and lower jaw from the Aptian-Albian 754:

or closely related, and it may have given rise to later forms of

8765: 4194: 4069:

Group of six juveniles that died together – specimen IVPP V14341

4034: 2632:. There is a flange on the dentary of the lower jaw, similar to 1678:, another small species, but suggested that additional study of 1449: 1096:

material from possibly the same locality was described later in

1085: 768:

through to adult, which has allowed several detailed studies of

660: 8711: 8128: 7597: 7448: 7410: 4219:

mammals preying on live dinosaurs. Heavy predation on juvenile

989:

Osborn published an additional description of the specimens of

7109:

Alexander, R. D. (1974). "The evolution of social behaviour".

5951:"MSU, Mongolian paleontologists find 67 dinosaurs in one week" 4762:

Sereno, Paul C. (1990). "New data on parrot-beaked dinosaurs (

4126:

specimens, only one has been described to possess any sort of

4053:

by using growth ring counts suggest that the longevity of the

3947:

nor generate propulsive force for locomotion, suggesting that

3859:, active throughout the day and for short intervals at night. 2569: 1682:

might reveal diagnostic features. He provisionally designated

1092:

and the remainder of the material being uncertain. Additional

7406: 7239:

Yaoming, Hu; Jin, Meng; Yuanqing, Wang; Chuankui, Li (2005).

1716:, near the border with Inner Mongolia. This species is named 1080:

as IVPP RV31039 and IVPP RV31040 respectively, come from the

894:

age. The specimen, catalogued as AMNH 6254, was described in

6621:

Bell, P. R.; Hendrickx, H.; Pittman, M.; Kaye, T.G. (2022).

3855:

and modern birds and reptiles suggest that it may have been

608: 4327:, most recent work dates it to the Early Cretaceous. Using 611: 599: 593: 6148:

Mayr, G.; Peters, S. D.; Plodowski, G.; Vogel, O. (2002).

6060:

Erickson, G. M.; Tumanova, T. A. (2000). "Growth curve of

4391:

The dinosaur book: the ruling reptiles and their relatives

2898:

are from Asia, meaning the group likely originated there.

1722:

Institute of Vertebrate Paleontology and Paleoanthropology

1661:

with seven other individuals. Russell and Zhao also named

1550:

Xinjiang. These specimens come from the upper part of the

1078:

Institute of Vertebrate Paleontology and Paleoanthropology

1044:

Following the discovery of material of psittacosaurids in

1009:, including the number of teeth, the number of pre-caudal 783:

has led to the labelling of Lower Cretaceous sediments of

4093:

Cast of a six-year-old specimen associated with juveniles

2598:

can reach 11.5 centimeters (4.5 in) in length.

2354:

to the structurally different integumentary filaments of

1812:

was contemporaneous with another psittacosaurid species,

1704:, another Chinese paleontologist, named a new species of 898:

by Osborn, only partially prepared, who gave it the name

587: 5684:

New data on cranial anatomy of the ceratopsian dinosaur

2386:

preserved with integument indicated that the animal was

1278:

were both known from Haratologay (also known as Tebch);

6775:

Proceedings of the Royal Society B: Biological Sciences

6236:

Proceedings of the Royal Society B: Biological Sciences

4802:(in Chinese). Beijing: Geology Press. pp. 123–136. 3760:

would have been similar to other ceratopsians with low

2775:, which is consistent with its greater geological age. 1147:. This material was described by Soviet paleontologist 7297:

Zhao, Q; Benton, M. J.; Xu, X.; Sander, M. J. (2014).

918:, which was found in the same expedition but from the 2857:, an opening in the skull between the eye socket and 1732:

through Aptian stages. Sereno suggested in 2000 that

1230:, but retained the species as separate giving former 851:

to discover fossils and geologic formations from the

623: 614: 605: 596: 584: 581: 5176: 5174: 5172: 5170: 5168: 5166: 5164: 5162: 4818:

Sereno, P. C.; Zhao, X.; Brown, L.; Tan, L. (2007).

4207:

mammal, is preserved with the remains of a juvenile

712:

was one of the earliest ceratopsians, but closer to

590: 504: 490: 470: 450: 433: 419: 402: 380: 362: 342: 325: 296: 8720: 8604: 8562: 8553: 8505: 8471: 8412: 8338: 8202: 8141: 8060: 8021: 7979: 7970: 7866: 7840: 7801: 7706: 7654: 7610: 7557: 7530: 7503: 6680:: Two Lower Cretaceous iguanodonts from Mongolia". 6282:Vinther, J.; Nicholls, R.; Kelly, Diane A. (2021). 5630:You, Hailu; Xu, Xing (2005). "An adult specimen of 4955: 4953: 4951: 4949: 4947: 4592:

The Sino-Swedish Expedition Publications 37, 113 pp

4448:: Two Lower Cretaceous iguanodonts from Mongolia". 4146:. The bone exhibits a large round pit, evidence of 2851:had only four digits on the hand. In addition, the 1708:in 1997, based on a complete skull with associated 602: 5240: 5238: 5236: 5234: 5232: 5230: 5228: 5226: 5224: 5143:Buffetaut, E.; Suteethorn, V. (2002). "Remarks on 4893:. Cambridge: Cambridge University Press. pp. 4774:. Cambridge: Cambridge University Press. pp. 3776:is 0.31, significantly higher than genera such as 2803:Reconstructed skeletons of an adult with juveniles 1427:Seventeen species have been referred to the genus 5728: 5726: 5724: 5405:(in Russian). Tomsk: GalaPress. pp. 363–366. 5030: 5028: 5026: 4813: 4811: 4809: 4770:Dinosaur Systematics: Perspectives and Approaches 4766:)". In Carpenter, Ken; Currie, Philip J. (eds.). 4687: 4685: 4567:Sereno, P.C. (1987). "The ornithischian dinosaur 2644:. It can be told apart from the other species of 2620:bones. Similar horns found on the postorbital of 2033:These specimens are generally all referred to as 1762:remains at a locality near Shestakovo village in 1104:, who considered the remains to likely belong to 847:took part in the Third Asiatic Expedition of the 7061:(Early Cretaceous, People's Republic of China)"" 7055:Zhao, Q.; Barrett, P. M.; Eberth, D. A. (2007). 5680:You, Hai-Lu; Tanoue, Kyo; Dodson, Peter (2008). 5675: 5673: 5419:Geological Society, London, Special Publications 5115: 5113: 4683: 4681: 4679: 4677: 4675: 4673: 4671: 4669: 4667: 4665: 4331:, a team of Chinese scientists dated the lowest 3784:behaviour could have been as complex as that in 2739:, with a proportionately longer skull and tail. 2229:to provide a sharp cutting surface for cropping 2174:, although neither is significantly larger than 1197:, in which he described multiple discoveries of 1060:, distinguished by its small size and lack of a 6055: 6053: 6051: 5782: 5780: 5778: 5733:Sereno, Paul C.; Xijin, Zhao; Lin, Tan (2010). 5518: 5516: 5496: 5494: 5312: 5310: 5308: 5306: 5304: 5302: 5300: 5298: 2556:' proportionally wider than in any other known 1712:and a forelimb. This material was recovered in 5944: 5942: 2759:. There is a fossa in front of the eye, as in 7422: 6875: 6873: 6089: 6087: 6017: 6015: 5847: 5845: 5843: 5841: 5458:from the Early Cretaceous of Western Siberia" 5291:. Beijing: China Ocean Press. pp. 48–67. 4879: 4877: 4875: 4868:. Beijing: China Ocean Press. pp. 75–80. 4859: 4857: 4855: 4853: 4851: 4849: 4847: 4757: 4755: 4753: 4751: 4749: 4725: 4723: 4721: 4487: 4485: 4483: 4481: 4479: 4264:fossils discovered so far have been found in 3927:skeleton casts in upright and crouching poses 2213:in some species. The portion in front of the 1554:, which is regarded as Aptian-Albian in age. 1193:, Yang published a paper on the dinosaurs of 8: 7325: 7323: 6442:"3D Camouflage in an Ornithischian Dinosaur" 6333:"3D Camouflage in an Ornithischian Dinosaur" 5789:"Parental care in an ornithischian dinosaur" 4562: 4560: 4558: 4477: 4475: 4473: 4471: 4469: 4467: 4465: 4463: 4461: 4459: 4435: 4433: 4407: 4405: 4403: 4401: 3931:Studies by Phil Senter in 2007 conducted on 3729:In 2005, Zhou and colleagues suggested that 2249:, but these are thought to be an example of 1925:("lizard"). This name refers to the ancient 6284:"A cloacal opening in a non-avian dinosaur" 6143: 6141: 6139: 6137: 5566: 5564: 5562: 5289:Sino-Japanese Silk Road Dinosaur Expedition 4889:The Age of Dinosaurs in Russia and Mongolia 4645: 4643: 4604: 4602: 4600: 4598: 4537:Bulletin of the Geological Society of China 4530: 4528: 4526: 4142:can be seen near the midpoint of the right 2847:or primitive trait, whereas all species of 2727:bone of the pelvis is also longer than the 2237:skulls share several adaptations with more 1254:, but not separate from each other, making 938:separate based on the lack of horns on the 8708: 8559: 8418: 8208: 8149: 8138: 8125: 8027: 7976: 7848: 7718: 7714: 7622: 7618: 7607: 7594: 7536: 7509: 7500: 7445: 7429: 7415: 7407: 2379:and offered protection against predators. 2118:vary in size and specific features of the 1945:, a professor at the IVPP in Beijing, who 1800:, named in 2006 by Chinese paleontologist 1537:In 1988, Zhao and American paleontologist 1392:, however. The front half of a skull from 1270:was the only species known from Shandong; 1111:The Soviet Expeditions into Mongolia from 970:, which he considered possibly related to 109: 20: 7241:"Large Mesozoic mammals fed on dinosaurs" 7159: 7031: 6853: 6843: 6794: 6701:Zoological Journal of the Linnean Society 6648: 6638: 6599:1983/029c668f-08b9-45f6-a0c5-30ce9256e593 6597: 6473: 6364: 6307: 6255: 6066:Zoological Journal of the Linnean Society 5758: 5704: 5606: 5596: 5278: 5276: 4421: 2767:. Widely flared jugals are also found in 2584:(lower jaw) lacks the hollow opening, or 2494:Restored heads of eight species, to scale 740:are all from Asia, with the exception of 7111:Annual Review of Ecology and Systematics 5124:from the Early Cretaceous of Thailand". 3434:in 2010. The middle one is shown below. 2829:to almost all known ceratopsians except 2470:, and found that it preserves the first 2457:A 2021 study of SMF R 4970 examined its 1612:of Thailand in 1992, giving it the name 1370:in the same 1931 report which contained 1358:In a 2010 review, Sereno again regarded 982:as the only member of the new subfamily 779:. The abundance of this dinosaur in the 8913:Multispecific non-avian dinosaur genera 7134: 7132: 5953:. Montana State University News Service 4380: 1475:In the 1950s, a new Chinese species of 1201:from a collection of localities of the 950:specimen could represent a juvenile of 323: 6987:University of Bristol (28 June 2013). 5283:Xu, Xing (1997). "A new psittacosaur ( 4991:Sereno, Paul C.; Xijin, Zhao (1988). " 4926:. San Diego: Academic Press. pp. 2695:has a flange similar to that found in 2150:), while others are somewhat smaller ( 2019:, which would normally have priority. 1981:, instead considering new combination 1649:and Zhao in 1996. The first was named 7334:biochron, Early Cretaceous of Asia". 6388:Panciroli, Elsa (14 September 2016). 6277: 6275: 5949:Boswell, Evelyn (13 September 2006). 4549:10.1111/j.1755-6724.1932.mp11003005.x 4394:. New York: McGraw-Hill. p. 153. 3862:Ford and Martin (2010) proposed that 2427:laser-stimulated fluorescence imaging 2205:is highly modified compared to other 1317:was considered to be most similar to 1064:on the parietal. The second species, 954:, based on similarities in size, the 736:forms. The genera closely related to 7: 8903:Taxa named by Henry Fairfield Osborn 3748:skull LHPV 1 from the left and above 7123:10.1146/annurev.es.05.110174.001545 6417:. 14 September 2016. Archived from 5187:Journal of Systematic Palaeontology 4009:have been found. The smallest is a 3879:were more terrestrial than others. 3635: 3611: 3587: 3563: 3513: 3506: 3456: 3449: 3437: 3273: 3249: 3199: 3192: 3142: 3135: 3111: 3087: 3034: 3022: 2972: 2965: 2941: 2911: 2901: 2544:and have less teeth. Uniquely, the 2294:Body details of specimen SMF R 4970 1820:; Sereno (2010), who proposed that 1515:and appears to be very similar, so 1396:in Inner Mongolia was described as 667:. It is notable for being the most 8853:Early Cretaceous dinosaurs of Asia 6748:10.1111/j.1755-6724.2003.tb00105.x 6713:10.1111/j.1096-3642.2000.tb02201.x 6078:10.1111/j.1096-3642.2000.tb02201.x 5739:Proceedings of the Royal Society B 5656:10.1111/j.1755-6724.2005.tb00879.x 5247:Canadian Journal of Earth Sciences 5084:Canadian Journal of Earth Sciences 5041:Journal of Vertebrate Paleontology 4997:Journal of Vertebrate Paleontology 4966:Canadian Journal of Earth Sciences 4015:American Museum of Natural History 2892:with the exception of their genus 2572:, at the contact of the jugal and 1290:was possibly known from Kemerovo. 849:American Museum of Natural History 815:American Museum of Natural History 14: 5642:(2) (English ed.): 168–173. 4268:sediments in Asia, from southern 2884:) noted that all taxa outside of 2624:are not as pronounced but may be 1452:and can only be evaluated from a 1382:; a table in the latter reported 1307:Beijing Museum of Natural History 1236:Psittacosaurus protiguanodonensis 1076:. Both specimens, stored in the 831:" holotype. Note the presence of 123:Children's Museum of Indianapolis 8692: 8691: 8667: 8661: 8111: 8105: 7394: 7088:10.1111/j.1475-4983.2007.00709.x 6108:10.1111/j.1469-7998.2007.00329.x 4836: 4370:Timeline of ceratopsian research 4349: 4185:remains preserved in its stomach 4057:ceratopsian was 10 to 11 years. 4033:mammals, but slower than modern 2604:is the largest-known species of 2506:, on the outside surface of the 2328:Most of the body was covered in 2287: 2271: 1889:Juveniles formerly described as 1846:One nearly complete skeleton of 1586:, near the town of Meileyingzi, 1305:for the specimen BPV.149 in the 1286:were both known form Oshih; and 962:. Osborn created the new family 577: 133: 7330:Lucas, Spencer G. (2006). "The 6734:(1) (English ed.): 15–20. 6500:Journal of Experimental Zoology 6415:"This Dinosaur Wore Camouflage" 4573:PhD Thesis, Columbia University 4513:Natural History of Central Asia 4155:animals, a similar injury to a 2158:). The smallest known species, 2090:of Mongolia. It is named after 1479:was found in the Aptian-Albian 1084:. An additional tooth, partial 750:. The first species was either 663:, existing between 125 and 105 16:Early Cretaceous dinosaur genus 5285:Psittacosaurus mazongshanensis 5061:10.1080/02724634.1988.10011725 5017:10.1080/02724634.1988.10011724 4611:Palaeontologia Sinica Series C 4311:The earliest known species is 2576:bones, a feature also seen in 1973:, and potentially the same as 1: 8918:Early Cretaceous ceratopsians 8898:Fossil taxa described in 1923 7356:10.1016/j.cretres.2005.11.011 7310:Acta Palaeontologica Polonica 7226:10.1016/j.cretres.2014.06.015 7152:Acta Palaeontologica Polonica 6026:The Encyclopedia of Dinosaurs 5878:10.1016/j.cretres.2006.08.005 5693:Acta Palaeontologica Polonica 5545:10.1016/j.cretres.2006.05.011 5465:Acta Palaeontologica Polonica 5037:Psittacosaurus meileyingensis 4922:The Encyclopedia of Dinosaurs 4827:Acta Palaeontologica Polonica 4138:, but very clear signs of an 4122:Out of the hundreds of known 3898:in its stomach region (arrow) 728:, it is now considered to be 7006:Psittacosaurus lujiatunensis 6894:10.1016/j.palwor.2007.07.002 6845:10.1371/journal.pone.0112055 5598:10.1371/journal.pone.0069265 5337:10.1016/j.palwor.2005.11.001 4993:Psittacosaurus xinjiangensis 4962:Psittacosaurus xinjiangensis 3430:and colleagues in 2008, and 2679:, and to a lesser degree in 1573:Copenhagen Zoological Museum 500:Sereno, Zhao & Tan, 2010 6697:Psittacosaurus mongoliensis 6562:"Structure and homology of 6230:Lingham-Soliar, T. (2008). 6062:Psittacosaurus mongoliensis 6030:. Academic Press. pp. 4799:Cheng, Zhengwu (1983). "". 4013:hatchling conserved in the 2667:has the shortest snout and 2134:. Several species approach 1645:were described by Canadian 1327:Psittacosaurus mongoliensis 1240:Psittacosaurus mongoliensis 1238:, as otherwise both it and 1173:Psittacosaurus mongoliensis 1125:Psittacosaurus mongoliensis 1119:uncovered more material of 1021:by American paleontologist 900:Psittacosaurus mongoliensis 301:Psittacosaurus mongoliensis 8934: 7373:Chinese Fossil Vertebrates 7369:Lucas, Spencer G. (2001). 6672:Osborn, Henry F. (1924). " 6640:10.1186/s12915-022-01329-9 4073:The find of a herd of six 2735:was probably smaller than 2260: 2257:Soft tissue and coloration 1917:: "hill"), as well as the 1901:in 2003. The generic name 1893:, Hong Kong Science Museum 1547:Xinjiang Autonomous Region 1398:Psittacosaurus guyangensis 1329:fossils are found in most 1226:to be a junior synonym of 1135:. Soviet excavations near 843:, American paleontologist 8681: 8659: 8421: 8211: 8152: 8137: 8124: 8102: 8030: 7851: 7721: 7717: 7625: 7621: 7606: 7593: 7539: 7512: 7499: 7444: 6682:American Museum Novitates 6466:10.1016/j.cub.2016.06.065 6357:10.1016/j.cub.2016.06.065 6309:10.1016/j.cub.2020.12.039 6181:10.1007/s00114-002-0339-6 5982:American Museum Novitates 5917:10.1007/s00114-002-0339-6 5207:10.1017/s1477201906001933 4450:American Museum Novitates 4414:American Museum Novitates 4280:fossils is from the late 3812:can be inferred from the 3762:encephalization quotients 3657: 3640: 3633: 3616: 3609: 3592: 3585: 3568: 3561: 3535: 3518: 3511: 3504: 3478: 3461: 3454: 3447: 3414:Although many species of 3293: 3278: 3271: 3254: 3247: 3221: 3204: 3197: 3190: 3164: 3147: 3140: 3133: 3116: 3109: 3092: 3085: 3056: 3039: 3032: 3020: 2994: 2977: 2970: 2963: 2946: 2939: 2919: 2909: 2421:Model based on SMF R 4970 2414:, based on hip features. 1726:Lower Xinminbao Formation 1503:. Chinese paleontologist 1495:to differentiate it from 1232:Protiguanodon mongoliense 1157:Protiguanodon mongoliense 1155:, who also proposed that 1129:Paleontological Institute 916:Protiguanodon mongoliense 533: 526: 316: 311: 295: 288: 130:Scientific classification 128: 117: 108: 23: 8873:Paleontology in Shandong 5456:Psittacosaurus sibiricus 5183:Psittacosaurus sibiricus 4650:Zhao, Xijin (1962). "". 4197:animal. One skeleton of 3894:specimen AMNH 6254 with 3426:and colleagues in 2006, 2594:. The skull of an adult 2425:Another 2016 study used 2193:Skeletal restoration of 2003:to be synonymous. While 1937:and only named species, 1491:. C. C. Young called it 1182:Holotype (IVPP V738) of 429:Russell & Zhao, 1996 7638:Micropachycephalosaurus 6929:10.1126/science.1200043 5976:Psittacosaurus amitabha 5503:Acta Petrologica Sinica 4247:Shanghai Ocean Aquarium 4045:study performed on the 2486:Species characteristics 2305:, or body covering, of 1207:Psittacosaurus sinensis 1082:Xinpongnaobao Formation 6787:10.1098/rspb.2006.3566 6248:10.1098/rspb.2007.1342 5751:10.1098/rspb.2009.0691 5477:10.4202/app.00819.2020 5379:10.1006/cres.2000.0242 4652:Vertebrata PalAsiatica 4440:Osborn, H.F. (1924). " 4319:put the Yixian in the 4250: 4186: 4094: 4070: 4002: 3928: 3907:, as in modern birds. 3899: 3805: 3749: 3411: 2861:, was lost during the 2815: 2804: 2495: 2422: 2198: 2162:, is 30% smaller than 2111: 1894: 1604:and a Thai colleague, 1600:French paleontologist 1575: 1424: 1301:, giving the new name 1186: 1161:Psittacosaurus osborni 1149:Anatoly Rozhdestvensky 1058:Psittacosaurus osborni 1041: 845:Henry Fairfield Osborn 836: 817: 813:(specimen AMNH 6254), 8878:Paleontology in Gansu 8813:Paleobiology Database 7161:10.4202/app.2012.0128 7012:Nature Communications 6728:Acta Geologica Sinica 6543:"Feathers or scales?" 5706:10.4202/app.2008.0202 5686:Psittacosaurus major" 5636:Acta Geologica Sinica 5439:10.1144/SP545-2023-62 4630:Voprosy Geologii Asii 4238: 4223:may have resulted in 4174: 4092: 4068: 3997:Skull of a hatchling 3996: 3922: 3890: 3800: 3744: 3402: 2810: 2802: 2493: 2420: 2392:disruptive coloration 2192: 2105: 2059:Museum of the Rockies 1905:was derived from the 1888: 1567: 1419: 1303:Psittacosaurus youngi 1284:P. protiguanodonensis 1234:the new species name 1181: 1032: 823: 805: 320:List of other species 8908:Ornithischian genera 8843:Ceratopsians of Asia 7403:at Wikimedia Commons 6421:on 15 September 2016 6219:doi:10.1038/35102731 5632:Hongshanosaurus houi 4296:). Many terrestrial 4200:Repenomamus robustus 4178:Repenomamus robustus 4061:Gregarious juveniles 2791:was a contemporary. 2446:and the "beards" of 2251:convergent evolution 2088:Andakhuduk Formation 2082:was named by Napoli 1961:skulls. He regarded 1899:Hongshanosaurus houi 1852:Psittacosaurus major 1814:Hongshanosaurus houi 1610:Khok Kruat Formation 1258:a junior synonym of 1165:Psittacosaurus tingi 920:Ondai Sair Formation 904:William King Gregory 798:History of discovery 8893:Fossils of Thailand 8888:Cretaceous Thailand 8863:Fossils of Mongolia 8858:Cretaceous Mongolia 8848:Feathered dinosaurs 7803:Archaeoceratopsidae 7348:2006CrRes..27..189L 7336:Cretaceous Research 7268:10.1038/nature03102 7260:2005Natur.433..149H 7218:2014CrRes..51..321H 7206:Cretaceous Research 7080:2007Palgy..50.1023Q 7024:2013NatCo...4.2079Z 6921:2011Sci...332..705S 6836:2014PLoSO...9k2055F 6781:(1598): 2135–2140. 6740:2003AcGlS..77...15Y 6582:2016Palgy..59..793M 6512:2003JEZ...297...27S 6458:2016CBio...26.2456V 6349:2016CBio...26.2456V 6300:2021CBio...31.R182V 6173:2002NW.....89..361M 6161:Naturwissenschaften 6130:doi:10.1038/414571a 5909:2002NW.....89..361M 5897:Naturwissenschaften 5870:2007CrRes..28..272L 5858:Cretaceous Research 5808:2004Natur.431..145M 5648:2005AcGlS..79..168Y 5589:2013PLoSO...869265H 5537:2007CrRes..28..177Y 5525:Cretaceous Research 5431:2023GSLSP.545...62I 5371:2001CrRes..22..115T 5359:Cretaceous Research 5259:1996CaJES..33..637R 5199:2006JSPal...4..359A 5096:1993CaJES..30.2101E 5053:1988JVPal...8..366S 5009:1988JVPal...8..353S 4365:Dinosaur coloration 4337:uranium–lead dating 4274:geologic formations 4239:Specimen alongside 3841:semicircular canals 3772:. The EQ score for 3424:Alexander Averianov 2854:antorbital fenestra 2814:skull in front view 2263:Feathered dinosaurs 2106:Size comparison of 2051:Bolortsetseg Minjin 2043:feathered dinosaurs 1780:Alexander Averianov 1665:in 1996, after the 1641:Two new species of 1606:Varavudh Suteethorn 1584:Jiufotang Formation 1023:Roy Chapman Andrews 8523:Crittendenceratops 8473:Albertaceratopsini 7033:10.1038/ncomms3079 6590:10.1111/pala.12257 6547:Journal of Geology 6541:Qiang, Ji (2016). 6096:Journal of Zoology 4329:argon–argon dating 4317:radiometric dating 4251: 4187: 4095: 4071: 4003: 3933:P. neimongoliensis 3929: 3900: 3806: 3750: 3596:P. neimongoliensis 3539:P. mazongshanensis 3412: 2916:Pachycephalosauria 2816: 2805: 2747:The type skull of 2733:P. neimongoliensis 2721:P. neimongoliensis 2548:bone contacts the 2496: 2423: 2319:Senckenberg Museum 2199: 2166:. The largest are 2144:P. neimongoliensis 2112: 1895: 1776:Alexei Voronkevich 1734:P. mazongshanensis 1718:P. mazongshanensis 1695:P. mazongshanensis 1672:P. neimongoliensis 1659:Ejinhoro Formation 1651:P. neimongoliensis 1631:P. neimongoliensis 1576: 1545:, named after the 1481:Qingshan Formation 1425: 1203:Qingshan Formation 1187: 1042: 984:Protiguanodontinae 978:within the family 974:, while he placed 881:Khukhtek Formation 837: 818: 438:P. mazongshanensis 407:P. neimongoliensis 8828: 8827: 8800:Open Tree of Life 8714:Taxon identifiers 8705: 8704: 8677: 8676: 8657: 8656: 8653: 8652: 8649: 8648: 8645: 8644: 8606:Pachyrhinosaurini 8544:Yehuecauhceratops 8507:Nasutoceratopsini 8408: 8407: 8120: 8119: 8100: 8099: 8096: 8095: 8092: 8091: 8088: 8087: 8084: 8083: 8080: 8079: 7981:Protoceratopsidae 7868:Leptoceratopsidae 7836: 7835: 7702: 7701: 7589: 7588: 7585: 7584: 7581: 7580: 7577: 7576: 7399:Media related to 7254:(7022): 149–152. 7139:Zhao, Q. (2013). 6973:978-0-253-35358-0 6452:(18): 2456–2462. 6343:(18): 2456–2462. 6242:(1636): 775–780. 5802:(7005): 145–146. 5745:(1679): 199–209. 5090:(10): 2101–2106. 4972:(12): 1781–1786. 4294:million years ago 4150:due to a lack of 4043:age determination 4005:Several juvenile 3726: 3725: 3717: 3716: 3708: 3707: 3699: 3698: 3690: 3689: 3681: 3680: 3672: 3671: 3644:P. meileyingensis 3550: 3549: 3493: 3492: 3396: 3395: 3387: 3386: 3378: 3377: 3369: 3368: 3360: 3359: 3351: 3350: 3342: 3341: 3333: 3332: 3324: 3323: 3315: 3314: 3306: 3305: 3281:Leptoceratopsidae 3236: 3235: 3179: 3178: 3071: 3070: 3009: 3008: 2886:Leptoceratopsidae 2709:P. meileyingensis 2665:P. meileyingensis 2638:P. meileyingensis 2516:P. meileyingensis 2374:tissue fibres in 2344:ultraviolet light 2315:Liaoning Province 2156:P. meileyingensis 1828:, opted to leave 1588:Liaoning Province 1580:P. meileyingensis 1569:P. meileyingensis 1559:P. meileyingensis 1485:Shandong Province 1349:Cretaceous Period 1250:as separate from 1040:from Osborn, 1923 772:growth rates and 687:. The species of 665:million years ago 568: 567: 562: 542: 519: 501: 487: 467: 447: 430: 416: 399: 377: 359: 347:P. meileyingensis 339: 284: 265: 119:P. meileyingensis 8925: 8868:Cretaceous China 8821: 8820: 8808: 8807: 8795: 8794: 8782: 8781: 8769: 8768: 8756: 8755: 8754: 8741: 8740: 8739: 8709: 8695: 8694: 8672: 8671: 8665: 8636:Pachyrhinosaurus 8560: 8434:Machairoceratops 8419: 8259:Coahuilaceratops 8209: 8150: 8139: 8126: 8115: 8110: 8109: 8028: 7977: 7961:Zhuchengceratops 7849: 7719: 7715: 7656:Chaoyangsauridae 7623: 7619: 7608: 7595: 7537: 7510: 7501: 7494: 7493: 7446: 7431: 7424: 7417: 7408: 7398: 7383: 7382: 7376: 7366: 7360: 7359: 7327: 7318: 7317: 7307: 7294: 7288: 7287: 7245: 7236: 7230: 7229: 7197: 7191: 7190: 7188: 7186: 7172: 7166: 7165: 7163: 7149: 7136: 7127: 7126: 7106: 7100: 7099: 7074:(5): 1023–1029. 7065: 7052: 7046: 7045: 7035: 6999: 6993: 6992: 6984: 6978: 6977: 6955: 6949: 6948: 6904: 6898: 6897: 6877: 6868: 6867: 6857: 6847: 6815: 6809: 6808: 6798: 6766: 6760: 6759: 6723: 6717: 6716: 6692: 6686: 6685: 6669: 6663: 6662: 6652: 6642: 6618: 6612: 6611: 6601: 6557: 6551: 6550: 6538: 6532: 6531: 6520:10.1002/jez.b.17 6494: 6488: 6487: 6477: 6437: 6431: 6430: 6428: 6426: 6411: 6405: 6404: 6402: 6400: 6385: 6379: 6378: 6368: 6328: 6322: 6321: 6311: 6294:(4): R182–R183. 6279: 6270: 6269: 6259: 6227: 6221: 6207: 6201: 6200: 6158: 6145: 6132: 6118: 6112: 6111: 6091: 6082: 6081: 6057: 6046: 6045: 6029: 6019: 6010: 6009: 5969: 5963: 5962: 5960: 5958: 5946: 5937: 5936: 5888: 5882: 5881: 5849: 5836: 5835: 5793: 5784: 5773: 5772: 5762: 5730: 5719: 5718: 5708: 5690: 5677: 5668: 5667: 5627: 5621: 5620: 5610: 5600: 5568: 5557: 5556: 5520: 5511: 5510: 5498: 5489: 5488: 5462: 5449: 5443: 5442: 5413: 5407: 5406: 5397: 5391: 5390: 5356: 5347: 5341: 5340: 5314: 5293: 5292: 5280: 5271: 5270: 5242: 5219: 5218: 5178: 5157: 5156: 5140: 5134: 5133: 5117: 5108: 5107: 5079: 5073: 5072: 5032: 5021: 5020: 4988: 4982: 4981: 4957: 4942: 4941: 4925: 4915: 4909: 4908: 4892: 4881: 4870: 4869: 4861: 4842: 4841: 4840: 4834: 4824: 4815: 4804: 4803: 4796: 4790: 4789: 4773: 4759: 4744: 4743: 4727: 4716: 4715: 4699: 4689: 4660: 4659: 4647: 4638: 4637: 4625: 4619: 4618: 4606: 4593: 4583: 4577: 4576: 4564: 4553: 4552: 4532: 4521: 4520: 4508: 4502: 4501: 4489: 4454: 4453: 4437: 4428: 4427: 4425: 4409: 4396: 4395: 4385: 4359: 4357:Dinosaurs portal 4354: 4353: 4352: 4313:P. lujiatunensis 4266:Early Cretaceous 3774:P. lujiatunensis 3754:P. lujiatunensis 3746:P. lujiatunensis 3731:P. lujiatunensis 3636: 3612: 3588: 3564: 3522:P. lujiatunensis 3514: 3507: 3457: 3450: 3438: 3274: 3250: 3200: 3193: 3143: 3136: 3112: 3088: 3035: 3023: 2973: 2966: 2942: 2912: 2902: 2837:Chaoyangsauridae 2835:and perhaps the 2749:P. lujiatunensis 2705:P. lujiatunensis 2677:P. lujiatunensis 2653:P. xinjiangensis 2566:P. lujiatunensis 2524:P. lujiatunensis 2504:antorbital fossa 2468:P. lujiatunensis 2311:Yixian Formation 2291: 2275: 2168:P. lujiatunensis 2148:P. xinjiangensis 2140:P. lujiatunensis 2130:(44 lb) in 2065:. Although only 2013:P. lujiatunensis 2009:P. lujiatunensis 2001:P. lujiatunensis 1975:P. lujiatunensis 1927:Hongshan culture 1913:: "red") and 山 ( 1907:Mandarin Chinese 1868:P. lujiatunensis 1856:P. lujiatunensis 1848:P. lujiatunensis 1830:P. lujiatunensis 1824:is a synonym of 1810:P. lujiatunensis 1806:Yixian Formation 1798:P. lujiatunensis 1792:P. lujiatunensis 1655:Mandarin Chinese 1543:P. xinjiangensis 1532:P. xinjiangensis 1412:Assigned species 1362:as a synonym of 964:Psittacosauridae 885:Early Cretaceous 827:AMNH 6253, the " 752:P. lujiatunensis 630: 626: 621: 620: 617: 616: 613: 610: 607: 604: 601: 598: 595: 592: 589: 586: 583: 549: 540: 513: 506: 499: 492: 479: 475:P. lujiatunensis 472: 459: 452: 442: 435: 428: 421: 415:& Zhao, 1996 411: 404: 390: 382: 371: 367:P. xinjiangensis 364: 351: 344: 334: 327: 298: 282: 275: 260: 257:Psittacosauridae 255: 242: 226: 210: 194: 138: 137: 113: 103: 40: 31:Early Cretaceous 29:Temporal range: 21: 8933: 8932: 8928: 8927: 8926: 8924: 8923: 8922: 8833: 8832: 8829: 8824: 8816: 8811: 8803: 8798: 8790: 8785: 8777: 8772: 8764: 8759: 8750: 8749: 8744: 8735: 8734: 8729: 8716: 8706: 8701: 8673: 8666: 8641: 8600: 8549: 8530:Furcatoceratops 8501: 8482:Albertaceratops 8467: 8441:Menefeeceratops 8404: 8377:Tatankaceratops 8334: 8280:Mercuriceratops 8231:Arrhinoceratops 8198: 8146: 8133: 8116: 8104: 8076: 8056: 8017: 7966: 7933:Montanoceratops 7862: 7857:Graciliceratops 7845: 7832: 7812:Archaeoceratops 7797: 7711: 7698: 7686:Xuanhuaceratops 7672:Hualianceratops 7650: 7631:Albalophosaurus 7615: 7602: 7573: 7553: 7526: 7520:Avemetatarsalia 7505:Avemetatarsalia 7495: 7489:Marginocephalia 7451: 7450: 7440: 7435: 7391: 7386: 7368: 7367: 7363: 7329: 7328: 7321: 7305: 7296: 7295: 7291: 7243: 7238: 7237: 7233: 7199: 7198: 7194: 7184: 7182: 7174: 7173: 7169: 7147: 7138: 7137: 7130: 7108: 7107: 7103: 7063: 7054: 7053: 7049: 7001: 7000: 6996: 6991:. ScienceDaily. 6986: 6985: 6981: 6974: 6957: 6956: 6952: 6915:(6030): 705–8. 6906: 6905: 6901: 6879: 6878: 6871: 6830:(12): e112055. 6817: 6816: 6812: 6768: 6767: 6763: 6725: 6724: 6720: 6694: 6693: 6689: 6671: 6670: 6666: 6620: 6619: 6615: 6559: 6558: 6554: 6540: 6539: 6535: 6496: 6495: 6491: 6446:Current Biology 6439: 6438: 6434: 6424: 6422: 6413: 6412: 6408: 6398: 6396: 6387: 6386: 6382: 6337:Current Biology 6330: 6329: 6325: 6288:Current Biology 6281: 6280: 6273: 6229: 6228: 6224: 6208: 6204: 6156: 6147: 6146: 6135: 6119: 6115: 6093: 6092: 6085: 6059: 6058: 6049: 6042: 6021: 6020: 6013: 5971: 5970: 5966: 5956: 5954: 5948: 5947: 5940: 5890: 5889: 5885: 5851: 5850: 5839: 5816:10.1038/431145a 5791: 5786: 5785: 5776: 5732: 5731: 5722: 5688: 5679: 5678: 5671: 5629: 5628: 5624: 5570: 5569: 5560: 5522: 5521: 5514: 5500: 5499: 5492: 5460: 5451: 5450: 5446: 5415: 5414: 5410: 5399: 5398: 5394: 5354: 5349: 5348: 5344: 5316: 5315: 5296: 5282: 5281: 5274: 5267:10.1139/e96-047 5244: 5243: 5222: 5180: 5179: 5160: 5142: 5141: 5137: 5119: 5118: 5111: 5104:10.1139/e93-182 5081: 5080: 5076: 5034: 5033: 5024: 4990: 4989: 4985: 4978:10.1139/e01-049 4959: 4958: 4945: 4938: 4917: 4916: 4912: 4905: 4883: 4882: 4873: 4863: 4862: 4845: 4835: 4822: 4817: 4816: 4807: 4798: 4797: 4793: 4786: 4761: 4760: 4747: 4729: 4728: 4719: 4712: 4691: 4690: 4663: 4649: 4648: 4641: 4627: 4626: 4622: 4608: 4607: 4596: 4584: 4580: 4566: 4565: 4556: 4534: 4533: 4524: 4510: 4509: 4505: 4491: 4490: 4457: 4439: 4438: 4431: 4411: 4410: 4399: 4387: 4386: 4382: 4378: 4355: 4350: 4348: 4345: 4321:Jurassic Period 4258:P. mongoliensis 4233: 4231:Paleochronology 4169: 4132:P. mongoliensis 4120: 4108:P. mongoliensis 4063: 4051:P. mongoliensis 4026:P. mongoliensis 4024:examination of 4011:P. mongoliensis 3999:P. mongoliensis 3991: 3937:P. mongoliensis 3925:P. mongoliensis 3917: 3892:P. mongoliensis 3885: 3823:sclerotic rings 3818:olfactory bulbs 3803:P. mongoliensis 3801:Restoration of 3739: 3727: 3718: 3709: 3700: 3691: 3682: 3673: 3661:P. mongoliensis 3551: 3494: 3405:P. mongoliensis 3397: 3388: 3379: 3370: 3361: 3352: 3343: 3334: 3325: 3316: 3307: 3237: 3225:Archaeoceratops 3180: 3072: 3060:P. mongoliensis 3010: 2981:Xuanhuaceratops 2906:Marginocephalia 2873:a second time. 2797: 2789:P. mongoliensis 2761:P. mongoliensis 2753:P. mongoliensis 2737:P. mongoliensis 2697:P. mongoliensis 2681:P. mongoliensis 2634:P. mongoliensis 2560:species except 2542:P. mongoliensis 2528:P. mongoliensis 2500:P. mongoliensis 2488: 2463:Psittacosaurus' 2444:horned screamer 2412:P. mongoliensis 2405:Jehol Formation 2299: 2298: 2297: 2296: 2295: 2292: 2284: 2283: 2276: 2265: 2259: 2176:P. mongoliensis 2164:P. mongoliensis 2136:P. mongoliensis 2132:P. mongoliensis 2124:P. mongoliensis 2114:The species of 2108:P. mongoliensis 2100: 2067:P. mongoliensis 1963:Hongshanosaurus 1959:Hongshanosaurus 1953:, Xu Xing, and 1933:was found. The 1931:Hongshanosaurus 1903:Hongshanosaurus 1891:Hongshanosaurus 1864:P. mongoliensis 1822:Hongshanosaurus 1768:Western Siberia 1764:Kemerovo Oblast 1501:P. mongoliensis 1497:P. mongoliensis 1487:, southeast of 1420:Restoration of 1414: 1402:P. mongoliensis 1380:P. mongoliensis 1364:P. mongoliensis 1288:P. mongoliensis 1280:P. mongoliensis 1276:P. mongoliensis 1252:P. mongoliensis 1169:junior synonyms 1106:P. mongoliensis 1038:P. mongoliensis 865:Oshih Formation 825:P. mongoliensis 811:P. mongoliensis 800: 726:Hongshanosaurus 659:of what is now 655:from the Early 628: 624: 580: 576: 548: 546:Hongshanosaurus 539: 522: 512: 498: 478: 458: 441: 427: 410: 389: 370: 350: 333: 322: 321: 307: 304: 281: 273: 259: 253: 240: 228:Marginocephalia 224: 208: 192: 132: 104: 102: 101: 96: 91: 86: 81: 76: 71: 66: 61: 56: 51: 46: 35: 34: 27: 17: 12: 11: 5: 8931: 8929: 8921: 8920: 8915: 8910: 8905: 8900: 8895: 8890: 8885: 8880: 8875: 8870: 8865: 8860: 8855: 8850: 8845: 8835: 8834: 8826: 8825: 8823: 8822: 8809: 8796: 8783: 8770: 8757: 8752:Psittacosaurus 8742: 8726: 8724: 8722:Psittacosaurus 8718: 8717: 8712: 8703: 8702: 8700: 8699: 8689: 8682: 8679: 8678: 8675: 8674: 8660: 8658: 8655: 8654: 8651: 8650: 8647: 8646: 8643: 8642: 8640: 8639: 8632: 8625: 8618: 8610: 8608: 8602: 8601: 8599: 8598: 8590: 8583: 8576: 8568: 8566: 8557: 8551: 8550: 8548: 8547: 8540: 8537:Nasutoceratops 8533: 8526: 8519: 8511: 8509: 8503: 8502: 8500: 8499: 8496:Medusaceratops 8492: 8485: 8477: 8475: 8469: 8468: 8466: 8465: 8458: 8451: 8444: 8437: 8430: 8427:Diabloceratops 8422: 8416: 8414:Centrosaurinae 8410: 8409: 8406: 8405: 8403: 8402: 8395: 8388: 8385:Titanoceratops 8381: 8373: 8370:Regaliceratops 8366: 8359: 8352: 8344: 8342: 8340:Triceratopsini 8336: 8335: 8333: 8332: 8325: 8318: 8311: 8304: 8301:Sierraceratops 8297: 8290: 8287:Navajoceratops 8283: 8276: 8269: 8262: 8255: 8248: 8241: 8234: 8227: 8220: 8212: 8206: 8204:Chasmosaurinae 8200: 8199: 8197: 8196: 8189: 8182: 8175: 8168: 8165:Brachyceratops 8161: 8153: 8147: 8142: 8135: 8134: 8129: 8122: 8121: 8118: 8117: 8103: 8101: 8098: 8097: 8094: 8093: 8090: 8089: 8086: 8085: 8082: 8081: 8078: 8077: 8075: 8074: 8073: 8072: 8066: 8064: 8058: 8057: 8055: 8054: 8047: 8044:Turanoceratops 8040: 8031: 8025: 8019: 8018: 8016: 8015: 8008: 8001: 7994: 7985: 7983: 7974: 7968: 7967: 7965: 7964: 7957: 7954:Unescoceratops 7950: 7943: 7936: 7929: 7922: 7919:Ischioceratops 7915: 7912:Gryphoceratops 7908: 7901: 7894: 7887: 7880: 7872: 7870: 7864: 7863: 7861: 7860: 7852: 7846: 7841: 7838: 7837: 7834: 7833: 7831: 7830: 7822: 7815: 7807: 7805: 7799: 7798: 7796: 7795: 7792:Sasayamagnomus 7788: 7781: 7774: 7767: 7759: 7752: 7745: 7742:Auroraceratops 7738: 7731: 7722: 7712: 7707: 7704: 7703: 7700: 7699: 7697: 7696: 7689: 7682: 7675: 7668: 7665:Chaoyangsaurus 7660: 7658: 7652: 7651: 7649: 7648: 7645:Psittacosaurus 7641: 7634: 7626: 7616: 7611: 7604: 7603: 7598: 7591: 7590: 7587: 7586: 7583: 7582: 7579: 7578: 7575: 7574: 7572: 7571: 7570: 7569: 7563: 7561: 7555: 7554: 7552: 7551: 7550: 7549: 7540: 7534: 7528: 7527: 7525: 7524: 7523: 7522: 7513: 7507: 7497: 7496: 7492: 7491: 7482: 7473: 7464: 7458: 7449: 7442: 7441: 7436: 7434: 7433: 7426: 7419: 7411: 7405: 7404: 7401:Psittacosaurus 7390: 7389:External links 7387: 7385: 7384: 7361: 7342:(2): 189–198. 7332:Psittacosaurus 7319: 7301:Psittacosaurus 7289: 7231: 7202:Psittacosaurus 7192: 7167: 7143:Psittacosaurus 7128: 7101: 7059:Psittacosaurus 7047: 6994: 6979: 6972: 6960:Psittacosaurus 6950: 6899: 6888:(4): 285–293. 6869: 6810: 6761: 6718: 6707:(4): 551–566. 6687: 6674:Psittacosaurus 6664: 6613: 6576:(6): 793–802. 6566:tail bristles" 6564:Psittacosaurus 6552: 6533: 6489: 6432: 6406: 6380: 6323: 6271: 6222: 6202: 6167:(8): 361–365. 6152:Psittacosaurus 6133: 6113: 6102:(3): 305–314. 6083: 6072:(4): 551–566. 6047: 6040: 6011: 5990:10.1206/3932.1 5984:(3932): 1–36. 5964: 5938: 5903:(8): 361–365. 5893:Psittacosaurus 5883: 5864:(2): 272–276. 5854:Psittacosaurus 5837: 5774: 5720: 5699:(2): 183–196. 5669: 5622: 5558: 5531:(2): 177–182. 5512: 5490: 5471:(2): 437–447. 5444: 5408: 5392: 5365:(1): 115–129. 5342: 5319:Psittacosaurus 5294: 5272: 5253:(4): 637–648. 5220: 5193:(4): 359–395. 5158: 5145:P. sattayaraki 5135: 5122:Psittacosaurus 5109: 5074: 5047:(4): 366–377. 5022: 5003:(4): 353–365. 4983: 4943: 4936: 4910: 4903: 4871: 4843: 4805: 4791: 4784: 4764:Psittacosaurus 4745: 4732:Psittacosaurus 4717: 4710: 4696:The Dinosauria 4661: 4654:(in Chinese). 4639: 4620: 4594: 4578: 4569:Psittacosaurus 4554: 4543:(3): 259–266. 4522: 4503: 4494:Psittacosaurus 4455: 4442:Psittacosaurus 4429: 4397: 4379: 4377: 4374: 4373: 4372: 4367: 4361: 4360: 4344: 4341: 4325:Psittacosaurus 4306:Psittacosaurus 4302:Psittacosaurus 4278:Psittacosaurus 4262:Psittacosaurus 4254:Psittacosaurus 4232: 4229: 4221:Psittacosaurus 4209:Psittacosaurus 4191:Psittacosaurus 4183:Psittacosaurus 4168: 4165: 4157:weight bearing 4124:Psittacosaurus 4119: 4116: 4099:Psittacosaurus 4080:gregariousness 4075:Psittacosaurus 4062: 4059: 4007:Psittacosaurus 3990: 3987: 3982:Psittacosaurus 3973:Psittacosaurus 3969:Psittacosaurus 3965:Psittacosaurus 3958:Psittacosaurus 3953:Psittacosaurus 3949:Psittacosaurus 3941:Psittacosaurus 3916: 3913: 3884: 3881: 3877:Psittacosaurus 3864:Psittacosaurus 3853:Psittacosaurus 3845:Psittacosaurus 3837:Psittacosaurus 3827:Psittacosaurus 3810:Psittacosaurus 3808:The senses of 3792:Psittacosaurus 3782:Psittacosaurus 3770:Psittacosaurus 3758:Psittacosaurus 3738: 3735: 3724: 3723: 3720: 3719: 3715: 3714: 3711: 3710: 3706: 3705: 3702: 3701: 3697: 3696: 3693: 3692: 3688: 3687: 3684: 3683: 3679: 3678: 3675: 3674: 3670: 3669: 3666: 3665: 3656: 3653: 3652: 3649: 3648: 3639: 3634: 3632: 3629: 3628: 3625: 3624: 3615: 3610: 3608: 3605: 3604: 3601: 3600: 3591: 3586: 3584: 3581: 3580: 3577: 3576: 3567: 3562: 3560: 3557: 3556: 3553: 3552: 3548: 3547: 3544: 3543: 3534: 3531: 3530: 3527: 3526: 3517: 3512: 3510: 3505: 3503: 3500: 3499: 3496: 3495: 3491: 3490: 3487: 3486: 3477: 3474: 3473: 3470: 3469: 3460: 3455: 3453: 3448: 3446: 3443:Psittacosaurus 3436: 3416:Psittacosaurus 3394: 3393: 3390: 3389: 3385: 3384: 3381: 3380: 3376: 3375: 3372: 3371: 3367: 3366: 3363: 3362: 3358: 3357: 3354: 3353: 3349: 3348: 3345: 3344: 3340: 3339: 3336: 3335: 3331: 3330: 3327: 3326: 3322: 3321: 3318: 3317: 3313: 3312: 3309: 3308: 3304: 3303: 3300: 3299: 3292: 3289: 3288: 3285: 3284: 3277: 3272: 3270: 3267: 3266: 3263: 3262: 3253: 3248: 3246: 3243: 3242: 3239: 3238: 3234: 3233: 3230: 3229: 3220: 3217: 3216: 3213: 3212: 3203: 3198: 3196: 3191: 3189: 3186: 3185: 3182: 3181: 3177: 3176: 3173: 3172: 3163: 3160: 3159: 3156: 3155: 3151:Auroraceratops 3146: 3141: 3139: 3134: 3132: 3129: 3128: 3125: 3124: 3115: 3110: 3108: 3105: 3104: 3101: 3100: 3091: 3086: 3084: 3078: 3077: 3074: 3073: 3069: 3068: 3065: 3064: 3055: 3052: 3051: 3048: 3047: 3038: 3033: 3031: 3028:Psittacosaurus 3021: 3019: 3016: 3015: 3012: 3011: 3007: 3006: 3003: 3002: 2998:Chaoyangsaurus 2993: 2990: 2989: 2986: 2985: 2976: 2971: 2969: 2964: 2962: 2959: 2958: 2955: 2954: 2945: 2940: 2938: 2932: 2931: 2928: 2927: 2918: 2910: 2908: 2900: 2878:Psittacosaurus 2849:Psittacosaurus 2841:Psittacosaurus 2819:Psittacosaurus 2796: 2795:Classification 2793: 2781:Psittacosaurus 2773:Psittacosaurus 2693:P. sattayaraki 2685:P. sattayaraki 2646:Psittacosaurus 2642:P. sattayaraki 2606:Psittacosaurus 2558:Psittacosaurus 2487: 2484: 2480:Psittacosaurus 2408:Psittacosaurus 2384:Psittacosaurus 2376:Psittacosaurus 2367:Psittacosaurus 2307:Psittacosaurus 2293: 2286: 2285: 2277: 2270: 2269: 2268: 2267: 2266: 2258: 2255: 2235:Psittacosaurus 2203:Psittacosaurus 2197:sp. SMF R 4970 2195:Psittacosaurus 2180:Psittacosaurus 2116:Psittacosaurus 2099: 2096: 2077: 2076: 2047:Psittacosaurus 2039:Psittacosaurus 2035:Psittacosaurus 2027: 2026: 1993:Psittacosaurus 1971:Psittacosaurus 1967:junior synonym 1883: 1882: 1844: 1843: 1826:Psittacosaurus 1795: 1794: 1784:Ilek Formation 1760:Psittacosaurus 1756: 1755: 1746:Psittacosaurus 1742:Psittacosaurus 1714:Gansu Province 1706:Psittacosaurus 1699: 1698: 1643:Psittacosaurus 1639: 1638: 1623:incertae sedis 1618:Psittacosaurus 1614:P. sattayaraki 1602:Eric Buffetaut 1598: 1597: 1595:P. sattayaraki 1562: 1561: 1535: 1534: 1521:P. guyangensis 1477:Psittacosaurus 1473: 1472: 1459:Psittacosaurus 1441:Psittacosaurus 1437:Psittacosaurus 1429:Psittacosaurus 1413: 1410: 1406:P. guyangensis 1336:dating to the 1264:Psittacosaurus 1228:Psittacosaurus 1220:Psittacosaurus 1215:Psittacosaurus 1199:Psittacosaurus 1145:Psittacosaurus 1121:Psittacosaurus 1094:Psittacosaurus 1070:Psittacosaurus 1062:sagittal crest 1054:Yang Zhongjian 1050:Inner Mongolia 1015:Psittacosaurus 1003:Psittacosaurus 995:Psittacosaurus 980:Iguanodontidae 968:Psittacosaurus 960:quadrate bones 956:parietal bones 952:Psittacosaurus 936:Psittacosaurus 912:Psittacosaurus 799: 796: 789:Psittacosaurus 770:Psittacosaurus 762:Psittacosaurus 756:Psittacosaurus 738:Psittacosaurus 730:senior synonym 710:Psittacosaurus 703:Psittacosaurus 691:were obligate 689:Psittacosaurus 572:Psittacosaurus 566: 565: 564: 563: 543: 531: 530: 524: 523: 521: 520: 502: 488: 468: 448: 431: 417: 400: 386:P. sattayaraki 378: 360: 340: 319: 318: 317: 314: 313: 312:Other species 309: 308: 305: 293: 292: 286: 285: 278:Psittacosaurus 271: 267: 266: 251: 247: 246: 238: 231: 230: 222: 215: 214: 212:Neornithischia 206: 199: 198: 190: 183: 182: 177: 170: 169: 164: 160: 159: 154: 150: 149: 144: 140: 139: 126: 125: 115: 114: 106: 105: 97: 92: 87: 82: 77: 72: 67: 62: 57: 52: 47: 42: 41: 28: 25:Psittacosaurus 15: 13: 10: 9: 6: 4: 3: 2: 8930: 8919: 8916: 8914: 8911: 8909: 8906: 8904: 8901: 8899: 8896: 8894: 8891: 8889: 8886: 8884: 8881: 8879: 8876: 8874: 8871: 8869: 8866: 8864: 8861: 8859: 8856: 8854: 8851: 8849: 8846: 8844: 8841: 8840: 8838: 8831: 8819: 8814: 8810: 8806: 8801: 8797: 8793: 8788: 8784: 8780: 8775: 8771: 8767: 8762: 8758: 8753: 8747: 8743: 8738: 8732: 8728: 8727: 8725: 8723: 8719: 8715: 8710: 8698: 8690: 8688: 8684: 8683: 8680: 8670: 8664: 8638: 8637: 8633: 8631: 8630: 8626: 8624: 8623: 8619: 8617: 8616: 8615:Achelousaurus 8612: 8611: 8609: 8607: 8603: 8596: 8595: 8594:Styracosaurus 8591: 8589: 8588: 8584: 8582: 8581: 8577: 8575: 8574: 8570: 8569: 8567: 8565: 8564:Centrosaurini 8561: 8558: 8556: 8555:Eucentrosaura 8552: 8546: 8545: 8541: 8539: 8538: 8534: 8532: 8531: 8527: 8525: 8524: 8520: 8518: 8517: 8513: 8512: 8510: 8508: 8504: 8498: 8497: 8493: 8491: 8490: 8486: 8484: 8483: 8479: 8478: 8476: 8474: 8470: 8464: 8463: 8459: 8457: 8456: 8455:Wendiceratops 8452: 8450: 8449: 8445: 8443: 8442: 8438: 8436: 8435: 8431: 8429: 8428: 8424: 8423: 8420: 8417: 8415: 8411: 8401: 8400: 8396: 8394: 8393: 8389: 8387: 8386: 8382: 8379: 8378: 8374: 8372: 8371: 8367: 8365: 8364: 8360: 8358: 8357: 8353: 8351: 8350: 8349:Eotriceratops 8346: 8345: 8343: 8341: 8337: 8331: 8330: 8326: 8324: 8323: 8319: 8317: 8316: 8312: 8310: 8309: 8305: 8303: 8302: 8298: 8296: 8295: 8294:Pentaceratops 8291: 8289: 8288: 8284: 8282: 8281: 8277: 8275: 8274: 8273:Kosmoceratops 8270: 8268: 8267: 8263: 8261: 8260: 8256: 8254: 8253: 8249: 8247: 8246: 8245:Bravoceratops 8242: 8240: 8239: 8238:Bisticeratops 8235: 8233: 8232: 8228: 8226: 8225: 8224:Anchiceratops 8221: 8219: 8218: 8217:Agujaceratops 8214: 8213: 8210: 8207: 8205: 8201: 8195: 8194: 8190: 8188: 8187: 8183: 8181: 8180: 8176: 8174: 8173: 8169: 8167: 8166: 8162: 8160: 8159: 8155: 8154: 8151: 8148: 8145: 8140: 8136: 8132: 8127: 8123: 8114: 8108: 8070: 8069: 8068: 8067: 8065: 8063: 8059: 8053: 8052: 8048: 8046: 8045: 8041: 8038: 8037: 8033: 8032: 8029: 8026: 8024: 8023:Ceratopsoidea 8020: 8014: 8013: 8012:Protoceratops 8009: 8007: 8006: 8005:Breviceratops 8002: 8000: 7999: 7995: 7992: 7991: 7987: 7986: 7984: 7982: 7978: 7975: 7973: 7969: 7963: 7962: 7958: 7956: 7955: 7951: 7949: 7948: 7947:Udanoceratops 7944: 7942: 7941: 7940:Prenoceratops 7937: 7935: 7934: 7930: 7928: 7927: 7926:Leptoceratops 7923: 7921: 7920: 7916: 7914: 7913: 7909: 7907: 7906: 7902: 7900: 7899: 7895: 7893: 7892: 7888: 7886: 7885: 7884:Bainoceratops 7881: 7879: 7878: 7874: 7873: 7871: 7869: 7865: 7859: 7858: 7854: 7853: 7850: 7847: 7844: 7839: 7828: 7827: 7823: 7821: 7820: 7819:Helioceratops 7816: 7814: 7813: 7809: 7808: 7806: 7804: 7800: 7794: 7793: 7789: 7787: 7786: 7785:Mosaiceratops 7782: 7780: 7779: 7775: 7773: 7772: 7768: 7765: 7764: 7760: 7758: 7757: 7756:Koreaceratops 7753: 7751: 7750: 7746: 7744: 7743: 7739: 7737: 7736: 7732: 7729: 7728: 7724: 7723: 7720: 7716: 7713: 7710: 7709:Neoceratopsia 7705: 7695: 7694: 7690: 7688: 7687: 7683: 7681: 7680: 7676: 7674: 7673: 7669: 7667: 7666: 7662: 7661: 7659: 7657: 7653: 7647: 7646: 7642: 7640: 7639: 7635: 7633: 7632: 7628: 7627: 7624: 7620: 7617: 7614: 7609: 7605: 7601: 7596: 7592: 7567: 7566: 7565: 7564: 7562: 7560: 7556: 7548: 7544: 7543: 7542: 7541: 7538: 7535: 7533: 7529: 7521: 7517: 7516: 7515: 7514: 7511: 7508: 7506: 7502: 7498: 7490: 7486: 7483: 7481: 7477: 7474: 7472: 7468: 7465: 7463: 7459: 7457: 7453: 7452: 7447: 7443: 7439: 7432: 7427: 7425: 7420: 7418: 7413: 7412: 7409: 7402: 7397: 7393: 7392: 7388: 7380: 7375: 7374: 7365: 7362: 7357: 7353: 7349: 7345: 7341: 7337: 7333: 7326: 7324: 7320: 7316:(4): 827–833. 7315: 7311: 7304: 7302: 7293: 7290: 7285: 7281: 7277: 7273: 7269: 7265: 7261: 7257: 7253: 7249: 7242: 7235: 7232: 7227: 7223: 7219: 7215: 7211: 7207: 7203: 7196: 7193: 7181: 7177: 7171: 7168: 7162: 7157: 7153: 7146: 7144: 7135: 7133: 7129: 7124: 7120: 7116: 7112: 7105: 7102: 7097: 7093: 7089: 7085: 7081: 7077: 7073: 7069: 7068:Palaeontology 7062: 7060: 7051: 7048: 7043: 7039: 7034: 7029: 7025: 7021: 7017: 7013: 7009: 7007: 6998: 6995: 6990: 6983: 6980: 6975: 6969: 6965: 6961: 6954: 6951: 6946: 6942: 6938: 6934: 6930: 6926: 6922: 6918: 6914: 6910: 6903: 6900: 6895: 6891: 6887: 6883: 6876: 6874: 6870: 6865: 6861: 6856: 6851: 6846: 6841: 6837: 6833: 6829: 6825: 6821: 6814: 6811: 6806: 6802: 6797: 6792: 6788: 6784: 6780: 6776: 6772: 6765: 6762: 6757: 6753: 6749: 6745: 6741: 6737: 6733: 6729: 6722: 6719: 6714: 6710: 6706: 6702: 6698: 6691: 6688: 6683: 6679: 6678:Protiguanodon 6675: 6668: 6665: 6660: 6656: 6651: 6646: 6641: 6636: 6632: 6628: 6624: 6617: 6614: 6609: 6605: 6600: 6595: 6591: 6587: 6583: 6579: 6575: 6571: 6570:Palaeontology 6567: 6565: 6556: 6553: 6548: 6544: 6537: 6534: 6529: 6525: 6521: 6517: 6513: 6509: 6505: 6501: 6493: 6490: 6485: 6481: 6476: 6471: 6467: 6463: 6459: 6455: 6451: 6447: 6443: 6436: 6433: 6420: 6416: 6410: 6407: 6395: 6391: 6384: 6381: 6376: 6372: 6367: 6362: 6358: 6354: 6350: 6346: 6342: 6338: 6334: 6327: 6324: 6319: 6315: 6310: 6305: 6301: 6297: 6293: 6289: 6285: 6278: 6276: 6272: 6267: 6263: 6258: 6253: 6249: 6245: 6241: 6237: 6233: 6226: 6223: 6220: 6217:(2001): 147. 6216: 6212: 6206: 6203: 6198: 6194: 6190: 6186: 6182: 6178: 6174: 6170: 6166: 6162: 6155: 6153: 6144: 6142: 6140: 6138: 6134: 6131: 6128:(2001): 571. 6127: 6123: 6117: 6114: 6109: 6105: 6101: 6097: 6090: 6088: 6084: 6079: 6075: 6071: 6067: 6063: 6056: 6054: 6052: 6048: 6043: 6041:9780122268106 6037: 6033: 6028: 6027: 6018: 6016: 6012: 6007: 6003: 5999: 5995: 5991: 5987: 5983: 5979: 5977: 5968: 5965: 5952: 5945: 5943: 5939: 5934: 5930: 5926: 5922: 5918: 5914: 5910: 5906: 5902: 5898: 5894: 5887: 5884: 5879: 5875: 5871: 5867: 5863: 5859: 5855: 5848: 5846: 5844: 5842: 5838: 5833: 5829: 5825: 5821: 5817: 5813: 5809: 5805: 5801: 5797: 5790: 5783: 5781: 5779: 5775: 5770: 5766: 5761: 5756: 5752: 5748: 5744: 5740: 5736: 5729: 5727: 5725: 5721: 5716: 5712: 5707: 5702: 5698: 5694: 5687: 5685: 5676: 5674: 5670: 5665: 5661: 5657: 5653: 5649: 5645: 5641: 5637: 5633: 5626: 5623: 5618: 5614: 5609: 5604: 5599: 5594: 5590: 5586: 5583:(8): e69265. 5582: 5578: 5574: 5567: 5565: 5563: 5559: 5554: 5550: 5546: 5542: 5538: 5534: 5530: 5526: 5519: 5517: 5513: 5508: 5504: 5497: 5495: 5491: 5486: 5482: 5478: 5474: 5470: 5466: 5459: 5457: 5448: 5445: 5440: 5436: 5432: 5428: 5424: 5420: 5412: 5409: 5404: 5396: 5393: 5388: 5384: 5380: 5376: 5372: 5368: 5364: 5360: 5353: 5346: 5343: 5338: 5334: 5330: 5326: 5325: 5320: 5313: 5311: 5309: 5307: 5305: 5303: 5301: 5299: 5295: 5290: 5286: 5279: 5277: 5273: 5268: 5264: 5260: 5256: 5252: 5248: 5241: 5239: 5237: 5235: 5233: 5231: 5229: 5227: 5225: 5221: 5216: 5212: 5208: 5204: 5200: 5196: 5192: 5188: 5184: 5177: 5175: 5173: 5171: 5169: 5167: 5165: 5163: 5159: 5154: 5150: 5146: 5139: 5136: 5131: 5127: 5126:Palaeontology 5123: 5116: 5114: 5110: 5105: 5101: 5097: 5093: 5089: 5085: 5078: 5075: 5070: 5066: 5062: 5058: 5054: 5050: 5046: 5042: 5038: 5031: 5029: 5027: 5023: 5018: 5014: 5010: 5006: 5002: 4998: 4994: 4987: 4984: 4979: 4975: 4971: 4967: 4963: 4956: 4954: 4952: 4950: 4948: 4944: 4939: 4937:9780122268106 4933: 4929: 4924: 4923: 4914: 4911: 4906: 4904:9780521554763 4900: 4896: 4891: 4890: 4880: 4878: 4876: 4872: 4867: 4860: 4858: 4856: 4854: 4852: 4850: 4848: 4844: 4839: 4833:(2): 275–284. 4832: 4828: 4821: 4814: 4812: 4810: 4806: 4801: 4795: 4792: 4787: 4785:9780521366724 4781: 4777: 4772: 4771: 4765: 4758: 4756: 4754: 4752: 4750: 4746: 4741: 4737: 4736:Palaeontology 4733: 4726: 4724: 4722: 4718: 4713: 4711:9780520242098 4707: 4703: 4698: 4697: 4688: 4686: 4684: 4682: 4680: 4678: 4676: 4674: 4672: 4670: 4668: 4666: 4662: 4657: 4653: 4646: 4644: 4640: 4635: 4631: 4624: 4621: 4616: 4612: 4605: 4603: 4601: 4599: 4595: 4591: 4587: 4582: 4579: 4574: 4570: 4563: 4561: 4559: 4555: 4550: 4546: 4542: 4538: 4531: 4529: 4527: 4523: 4518: 4514: 4507: 4504: 4499: 4495: 4488: 4486: 4484: 4482: 4480: 4478: 4476: 4474: 4472: 4470: 4468: 4466: 4464: 4462: 4460: 4456: 4451: 4447: 4446:Protiguanodon 4443: 4436: 4434: 4430: 4424: 4419: 4415: 4408: 4406: 4404: 4402: 4398: 4393: 4392: 4384: 4381: 4375: 4371: 4368: 4366: 4363: 4362: 4358: 4347: 4342: 4340: 4338: 4334: 4330: 4326: 4322: 4318: 4314: 4309: 4307: 4303: 4299: 4295: 4291: 4287: 4283: 4279: 4275: 4271: 4267: 4263: 4259: 4255: 4248: 4244: 4243: 4237: 4230: 4228: 4226: 4222: 4218: 4214: 4210: 4206: 4202: 4201: 4196: 4192: 4184: 4180: 4179: 4173: 4166: 4164: 4162: 4158: 4153: 4149: 4145: 4141: 4137: 4136:bone fracture 4133: 4129: 4125: 4117: 4115: 4111: 4109: 4105: 4100: 4091: 4087: 4085: 4081: 4076: 4067: 4060: 4058: 4056: 4052: 4048: 4044: 4040: 4036: 4032: 4029:reptiles and 4027: 4023: 4018: 4016: 4012: 4008: 4000: 3995: 3988: 3986: 3983: 3979: 3978:Psittacosaurs 3974: 3970: 3966: 3961: 3959: 3954: 3950: 3946: 3942: 3938: 3934: 3926: 3921: 3915:Limb function 3914: 3912: 3908: 3906: 3897: 3893: 3889: 3882: 3880: 3878: 3874: 3870: 3865: 3860: 3858: 3854: 3850: 3849:scleral rings 3846: 3842: 3838: 3834: 3833: 3832:Protoceratops 3828: 3824: 3819: 3815: 3811: 3804: 3799: 3795: 3793: 3789: 3788: 3787:Tyrannosaurus 3783: 3779: 3775: 3771: 3767: 3763: 3759: 3755: 3752:The brain of 3747: 3743: 3736: 3734: 3732: 3722: 3721: 3713: 3712: 3704: 3703: 3695: 3694: 3686: 3685: 3677: 3676: 3668: 3667: 3664: 3663: 3662: 3655: 3654: 3651: 3650: 3647: 3646: 3645: 3638: 3637: 3631: 3630: 3627: 3626: 3623: 3622: 3621: 3620:P. ordosensis 3614: 3613: 3607: 3606: 3603: 3602: 3599: 3598: 3597: 3590: 3589: 3583: 3582: 3579: 3578: 3575: 3574: 3573: 3566: 3565: 3559: 3558: 3555: 3554: 3546: 3545: 3542: 3541: 3540: 3533: 3532: 3529: 3528: 3525: 3524: 3523: 3516: 3515: 3509: 3508: 3502: 3501: 3498: 3497: 3489: 3488: 3485: 3484: 3483: 3476: 3475: 3472: 3471: 3468: 3467: 3466: 3459: 3458: 3452: 3451: 3445: 3444: 3440: 3439: 3435: 3433: 3429: 3425: 3421: 3417: 3410: 3406: 3401: 3392: 3391: 3383: 3382: 3374: 3373: 3365: 3364: 3356: 3355: 3347: 3346: 3338: 3337: 3329: 3328: 3320: 3319: 3311: 3310: 3302: 3301: 3298: 3297: 3291: 3290: 3287: 3286: 3283: 3282: 3276: 3275: 3269: 3268: 3265: 3264: 3261: 3260: 3259: 3258:Koreaceratops 3252: 3251: 3245: 3244: 3241: 3240: 3232: 3231: 3228: 3227: 3226: 3219: 3218: 3215: 3214: 3211: 3210: 3209: 3208:Helioceratops 3202: 3201: 3195: 3194: 3188: 3187: 3184: 3183: 3175: 3174: 3171: 3170: 3169: 3162: 3161: 3158: 3157: 3154: 3153: 3152: 3145: 3144: 3138: 3137: 3131: 3130: 3127: 3126: 3123: 3122: 3121: 3114: 3113: 3107: 3106: 3103: 3102: 3099: 3098: 3097: 3090: 3089: 3083: 3082:Neoceratopsia 3080: 3079: 3076: 3075: 3067: 3066: 3063: 3062: 3061: 3054: 3053: 3050: 3049: 3046: 3045: 3044: 3037: 3036: 3030: 3029: 3025: 3024: 3018: 3017: 3014: 3013: 3005: 3004: 3001: 3000: 2999: 2992: 2991: 2988: 2987: 2984: 2983: 2982: 2975: 2974: 2968: 2967: 2961: 2960: 2957: 2956: 2953: 2952: 2951: 2944: 2943: 2937: 2934: 2933: 2930: 2929: 2926: 2925: 2924: 2917: 2914: 2913: 2907: 2904: 2903: 2899: 2897: 2896: 2891: 2887: 2883: 2879: 2874: 2872: 2868: 2864: 2860: 2856: 2855: 2850: 2846: 2842: 2838: 2834: 2833: 2828: 2824: 2820: 2813: 2809: 2801: 2794: 2792: 2790: 2786: 2782: 2778: 2774: 2770: 2766: 2762: 2758: 2754: 2750: 2745: 2742: 2741:P. ordosensis 2738: 2734: 2730: 2726: 2722: 2718: 2714: 2710: 2706: 2702: 2698: 2694: 2690: 2686: 2682: 2678: 2674: 2670: 2666: 2662: 2658: 2654: 2650: 2647: 2643: 2639: 2635: 2631: 2627: 2623: 2619: 2615: 2611: 2607: 2603: 2599: 2597: 2593: 2589: 2588: 2583: 2579: 2575: 2571: 2567: 2563: 2559: 2555: 2551: 2547: 2543: 2539: 2535: 2533: 2529: 2525: 2521: 2517: 2513: 2509: 2505: 2501: 2492: 2485: 2483: 2481: 2477: 2473: 2469: 2464: 2460: 2455: 2453: 2449: 2445: 2441: 2440: 2439:Beipiaosaurus 2435: 2434: 2428: 2419: 2415: 2413: 2409: 2406: 2401: 2397: 2393: 2389: 2388:countershaded 2385: 2380: 2377: 2373: 2368: 2364: 2359: 2357: 2353: 2349: 2345: 2341: 2337: 2336: 2331: 2326: 2324: 2320: 2316: 2312: 2308: 2304: 2290: 2281: 2274: 2264: 2256: 2254: 2252: 2248: 2244: 2240: 2236: 2232: 2228: 2224: 2220: 2216: 2212: 2208: 2207:ornithischian 2204: 2201:The skull of 2196: 2191: 2187: 2185: 2181: 2177: 2173: 2169: 2165: 2161: 2160:P. ordosensis 2157: 2153: 2149: 2145: 2141: 2137: 2133: 2129: 2125: 2121: 2117: 2109: 2104: 2097: 2095: 2093: 2089: 2085: 2081: 2075: 2072: 2071: 2070: 2068: 2064: 2060: 2056: 2053:and American 2052: 2048: 2044: 2040: 2036: 2031: 2025: 2022: 2021: 2020: 2018: 2014: 2010: 2006: 2002: 1998: 1994: 1990: 1989: 1984: 1980: 1976: 1972: 1968: 1964: 1960: 1956: 1952: 1948: 1944: 1940: 1936: 1932: 1928: 1924: 1920: 1916: 1912: 1908: 1904: 1900: 1892: 1887: 1880: 1877: 1876: 1875: 1873: 1869: 1865: 1861: 1857: 1853: 1849: 1842: 1839: 1838: 1837: 1835: 1831: 1827: 1823: 1819: 1815: 1811: 1807: 1803: 1802:Zhou Chang-Fu 1799: 1793: 1790: 1789: 1788: 1785: 1781: 1777: 1773: 1769: 1765: 1761: 1754: 1751: 1750: 1749: 1747: 1743: 1739: 1735: 1731: 1727: 1723: 1719: 1715: 1711: 1707: 1703: 1696: 1693: 1692: 1691: 1689: 1685: 1684:P. ordosensis 1681: 1680:P. ordosensis 1677: 1673: 1668: 1664: 1663:P. ordosensis 1660: 1656: 1652: 1648: 1644: 1636: 1635:P. ordosensis 1632: 1629: 1628: 1627: 1625: 1624: 1619: 1615: 1611: 1607: 1603: 1596: 1593: 1592: 1591: 1589: 1585: 1581: 1574: 1570: 1566: 1560: 1557: 1556: 1555: 1553: 1548: 1544: 1540: 1533: 1530: 1529: 1528: 1526: 1522: 1518: 1514: 1510: 1506: 1502: 1498: 1494: 1490: 1486: 1482: 1478: 1471: 1468: 1467: 1466: 1464: 1460: 1455: 1454:morphological 1451: 1446: 1442: 1438: 1434: 1430: 1423: 1418: 1411: 1409: 1407: 1403: 1399: 1395: 1394:Guyang County 1391: 1390: 1385: 1381: 1377: 1373: 1369: 1365: 1361: 1356: 1354: 1350: 1347:of the Early 1346: 1343: 1339: 1335: 1332: 1328: 1322: 1320: 1316: 1312: 1308: 1304: 1300: 1296: 1291: 1289: 1285: 1281: 1277: 1274:and possibly 1273: 1269: 1265: 1261: 1257: 1253: 1249: 1245: 1241: 1237: 1233: 1229: 1225: 1224:Protiguanodon 1221: 1216: 1212: 1208: 1204: 1200: 1196: 1192: 1185: 1180: 1176: 1174: 1170: 1166: 1162: 1158: 1154: 1150: 1146: 1142: 1138: 1134: 1130: 1126: 1122: 1118: 1114: 1109: 1107: 1103: 1102:Birger Bohlin 1099: 1095: 1091: 1090:Protiguanodon 1087: 1083: 1079: 1075: 1074:Protiguanodon 1071: 1067: 1063: 1059: 1055: 1051: 1047: 1039: 1035: 1031: 1027: 1024: 1020: 1016: 1012: 1008: 1007:Protiguanodon 1004: 1000: 996: 992: 991:Protiguanodon 987: 985: 981: 977: 976:Protiguanodon 973: 969: 965: 961: 957: 953: 949: 948:Protiguanodon 945: 944:Protiguanodon 941: 937: 933: 932:Protiguanodon 929: 928:Protiguanodon 925: 921: 917: 913: 909: 905: 901: 897: 893: 889: 886: 882: 878: 874: 870: 866: 862: 858: 854: 850: 846: 842: 834: 830: 829:Protiguanodon 826: 822: 816: 812: 808: 804: 797: 795: 793: 790: 786: 782: 781:fossil record 778: 775: 771: 767: 763: 759: 757: 753: 749: 748:North America 745: 744: 739: 735: 731: 727: 723: 722: 717: 716: 711: 707: 704: 700: 699: 694: 690: 686: 682: 678: 674: 670: 666: 662: 658: 654: 651: 648: 644: 640: 637: 633: 632: 619: 574: 573: 560: 556: 552: 547: 544: 538: 537:Protiguanodon 535: 534: 532: 529: 525: 517: 511: 510: 503: 497: 496: 489: 485: 482: 477: 476: 469: 465: 462: 457: 456: 449: 445: 440: 439: 432: 426: 425: 424:P. ordosensis 418: 414: 409: 408: 401: 397: 393: 388: 387: 379: 375: 372:Sereno & 369: 368: 361: 357: 354: 349: 348: 341: 337: 332: 331: 324: 315: 310: 303: 302: 294: 291: 287: 280: 279: 272: 269: 268: 263: 258: 252: 249: 248: 245: 239: 236: 233: 232: 229: 223: 220: 217: 216: 213: 207: 204: 201: 200: 197: 191: 188: 185: 184: 181: 178: 175: 172: 171: 168: 165: 162: 161: 158: 155: 152: 151: 148: 145: 142: 141: 136: 131: 127: 124: 120: 116: 112: 107: 100: 95: 90: 85: 80: 75: 70: 65: 60: 55: 50: 45: 39: 36:125–105 32: 26: 22: 19: 8883:Yixian fauna 8830: 8721: 8634: 8629:Stellasaurus 8627: 8620: 8613: 8592: 8585: 8580:Coronosaurus 8578: 8573:Centrosaurus 8571: 8542: 8535: 8528: 8521: 8514: 8494: 8489:Lokiceratops 8487: 8480: 8462:Xenoceratops 8460: 8453: 8448:Sinoceratops 8446: 8439: 8432: 8425: 8397: 8390: 8383: 8375: 8368: 8361: 8356:Nedoceratops 8354: 8347: 8329:Vagaceratops 8327: 8322:Utahceratops 8320: 8315:Terminocavus 8313: 8306: 8299: 8292: 8285: 8278: 8271: 8266:Judiceratops 8264: 8257: 8252:Chasmosaurus 8250: 8243: 8236: 8229: 8222: 8215: 8191: 8184: 8177: 8170: 8163: 8156: 8144:Ceratopsidae 8131:Ceratopsidae 8062:Ceratopsidae 8051:Zuniceratops 8049: 8042: 8036:Ajkaceratops 8034: 8010: 8003: 7998:Bagaceratops 7996: 7990:Ajkaceratops 7988: 7972:Coronosauria 7959: 7952: 7945: 7938: 7931: 7924: 7917: 7910: 7903: 7896: 7889: 7882: 7877:Asiaceratops 7875: 7855: 7843:Euceratopsia 7826:Yamaceratops 7824: 7817: 7810: 7790: 7783: 7778:Microceratus 7776: 7771:Liaoceratops 7769: 7761: 7754: 7747: 7740: 7733: 7727:Ajkaceratops 7725: 7691: 7684: 7677: 7670: 7663: 7644: 7643: 7636: 7629: 7547:Ornithischia 7532:Ornithischia 7484: 7480:Ornithischia 7475: 7466: 7372: 7364: 7339: 7335: 7331: 7313: 7309: 7300: 7292: 7251: 7247: 7234: 7209: 7205: 7201: 7195: 7183:. Retrieved 7179: 7170: 7151: 7142: 7114: 7110: 7104: 7071: 7067: 7058: 7050: 7015: 7011: 7005: 6997: 6982: 6963: 6959: 6953: 6912: 6908: 6902: 6885: 6881: 6827: 6823: 6813: 6778: 6774: 6764: 6731: 6727: 6721: 6704: 6700: 6696: 6690: 6684:(127): 1–16. 6681: 6677: 6673: 6667: 6630: 6626: 6616: 6573: 6569: 6563: 6555: 6546: 6536: 6506:(1): 27–34. 6503: 6499: 6492: 6449: 6445: 6435: 6425:15 September 6423:. Retrieved 6419:the original 6409: 6399:15 September 6397:. Retrieved 6394:The Guardian 6393: 6383: 6340: 6336: 6326: 6291: 6287: 6239: 6235: 6225: 6214: 6210: 6205: 6164: 6160: 6151: 6125: 6121: 6116: 6099: 6095: 6069: 6065: 6061: 6025: 5981: 5975: 5967: 5955:. Retrieved 5900: 5896: 5892: 5886: 5861: 5857: 5853: 5799: 5795: 5742: 5738: 5696: 5692: 5683: 5639: 5635: 5631: 5625: 5580: 5576: 5528: 5524: 5506: 5502: 5468: 5464: 5455: 5447: 5422: 5418: 5411: 5402: 5395: 5362: 5358: 5345: 5328: 5322: 5318: 5288: 5284: 5250: 5246: 5190: 5186: 5182: 5152: 5148: 5144: 5138: 5129: 5125: 5121: 5087: 5083: 5077: 5044: 5040: 5036: 5000: 4996: 4992: 4986: 4969: 4965: 4961: 4921: 4913: 4888: 4865: 4830: 4826: 4800: 4794: 4769: 4763: 4739: 4735: 4731: 4695: 4655: 4651: 4633: 4629: 4623: 4614: 4610: 4589: 4581: 4572: 4568: 4540: 4536: 4516: 4512: 4506: 4497: 4493: 4452:(127): 1–16. 4449: 4445: 4441: 4416:(13): 1–10. 4413: 4390: 4383: 4324: 4312: 4310: 4305: 4301: 4277: 4261: 4257: 4253: 4252: 4240: 4220: 4208: 4198: 4190: 4188: 4182: 4176: 4131: 4123: 4121: 4112: 4107: 4098: 4096: 4074: 4072: 4050: 4041:mammals. An 4025: 4022:histological 4019: 4010: 4006: 4004: 3998: 3981: 3977: 3972: 3968: 3964: 3962: 3957: 3952: 3948: 3940: 3936: 3932: 3930: 3924: 3909: 3901: 3891: 3876: 3863: 3861: 3852: 3844: 3836: 3830: 3826: 3809: 3807: 3802: 3791: 3785: 3781: 3777: 3773: 3769: 3757: 3753: 3751: 3745: 3737:Paleobiology 3730: 3728: 3660: 3659: 3658: 3643: 3642: 3641: 3619: 3618: 3617: 3595: 3594: 3593: 3571: 3570: 3569: 3538: 3537: 3536: 3521: 3520: 3519: 3482:P. sibiricus 3481: 3480: 3479: 3464: 3463: 3462: 3442: 3441: 3420:phylogenetic 3415: 3413: 3404: 3296:Coronosauria 3294: 3279: 3256: 3255: 3223: 3222: 3206: 3205: 3168:Yamaceratops 3166: 3165: 3149: 3148: 3118: 3117: 3096:Liaoceratops 3094: 3093: 3059: 3058: 3057: 3042: 3041: 3040: 3027: 3026: 2996: 2995: 2979: 2978: 2948: 2947: 2921: 2920: 2893: 2890:Coronosauria 2881: 2877: 2875: 2852: 2848: 2845:plesiomorphy 2840: 2830: 2818: 2817: 2812:P. sibiricus 2811: 2788: 2780: 2777:P. gobiensis 2776: 2772: 2769:P. sibiricus 2768: 2764: 2760: 2757:P. sibiricus 2756: 2752: 2748: 2746: 2740: 2736: 2732: 2720: 2717:frontal bone 2712: 2708: 2704: 2701:P. sibiricus 2700: 2696: 2692: 2689:P. sibiricus 2688: 2684: 2680: 2676: 2664: 2652: 2651: 2645: 2641: 2637: 2633: 2629: 2621: 2614:P. sibiricus 2613: 2605: 2602:P. sibiricus 2601: 2600: 2595: 2585: 2578:P. sibiricus 2577: 2565: 2562:P. sibiricus 2561: 2557: 2546:premaxillary 2541: 2537: 2536: 2527: 2523: 2519: 2515: 2499: 2497: 2479: 2467: 2462: 2456: 2437: 2431: 2424: 2411: 2407: 2383: 2381: 2375: 2366: 2360: 2335:Chasmosaurus 2333: 2327: 2306: 2300: 2247:P. sibiricus 2246: 2234: 2222: 2218: 2202: 2200: 2194: 2179: 2175: 2172:P. sibiricus 2171: 2167: 2163: 2159: 2155: 2151: 2147: 2143: 2139: 2135: 2131: 2123: 2115: 2113: 2107: 2083: 2079: 2078: 2073: 2066: 2046: 2038: 2034: 2030:P. gobiensis 2029: 2028: 2024:P. gobiensis 2023: 2016: 2015:rather than 2012: 2008: 2004: 2000: 1996: 1992: 1988:nomen dubium 1986: 1982: 1978: 1974: 1970: 1962: 1958: 1955:Wang Xiaolin 1938: 1930: 1922: 1914: 1910: 1902: 1898: 1896: 1890: 1878: 1871: 1867: 1863: 1859: 1855: 1851: 1847: 1845: 1840: 1833: 1829: 1825: 1821: 1817: 1813: 1809: 1797: 1796: 1791: 1772:P. sibiricus 1771: 1759: 1757: 1753:P. sibiricus 1752: 1745: 1741: 1738:nomen dubium 1737: 1733: 1717: 1705: 1700: 1694: 1688:nomen dubium 1687: 1683: 1679: 1675: 1671: 1662: 1653:, after the 1650: 1647:Dale Russell 1642: 1640: 1634: 1630: 1621: 1617: 1613: 1599: 1594: 1579: 1577: 1568: 1558: 1552:Tugulu Group 1542: 1536: 1531: 1524: 1520: 1516: 1512: 1508: 1500: 1496: 1492: 1476: 1474: 1469: 1458: 1440: 1436: 1433:monospecific 1428: 1426: 1422:P. sibiricus 1421: 1405: 1401: 1397: 1389:nomen dubium 1387: 1383: 1379: 1375: 1371: 1367: 1363: 1359: 1357: 1326: 1323: 1318: 1314: 1310: 1302: 1292: 1287: 1283: 1279: 1275: 1271: 1267: 1263: 1259: 1255: 1251: 1247: 1243: 1239: 1235: 1231: 1227: 1223: 1219: 1214: 1206: 1198: 1188: 1183: 1172: 1164: 1160: 1156: 1144: 1124: 1120: 1110: 1105: 1093: 1089: 1073: 1069: 1065: 1057: 1043: 1037: 1014: 1006: 1002: 994: 990: 988: 975: 972:Ankylosauria 967: 951: 947: 943: 935: 931: 927: 915: 911: 899: 838: 828: 824: 810: 788: 774:reproductive 769: 761: 760: 755: 751: 741: 737: 725: 719: 713: 709: 708: 702: 696: 688: 571: 570: 569: 545: 541:Osborn, 1923 536: 515: 508: 507: 495:P. gobiensis 494: 493: 483: 474: 473: 463: 461:Leshchinskiy 455:P. sibiricus 454: 453: 437: 436: 423: 422: 406: 405: 385: 384: 366: 365: 355: 346: 345: 329: 328: 306:Osborn, 1923 300: 299: 290:Type species 283:Osborn, 1923 277: 276: 256: 234: 218: 202: 196:Ornithischia 186: 173: 118: 24: 18: 8746:Wikispecies 8622:Einiosaurus 8516:Avaceratops 8399:Triceratops 8363:Ojoceratops 8186:Monoclonius 7898:Ferrisaurus 7763:Kulceratops 7377:. pp. 7212:: 321–340. 7117:: 325–383. 6882:Palaeoworld 6627:BMC Biology 5331:: 100–114. 5324:Palaeoworld 4298:sedimentary 4225:R-selection 4213:carnivorous 4205:triconodont 4181:, juvenile 4049:remains of 3989:Growth rate 3985:evolution. 3896:gastroliths 3873:gastroliths 3778:Triceratops 3465:P. sinensis 3432:Paul Sereno 3409:Dinosaurium 3043:P. sinensis 2785:postorbital 2765:P. sinensis 2713:P. sinensis 2630:P. sinensis 2622:P. sinensis 2596:P. sinensis 2574:postorbital 2538:P. sinensis 2348:keratinized 2152:P. sinensis 2128:kilogrammes 2110:to a human. 2098:Description 2080:P. amitabha 2074:P. amitabha 2055:Jack Horner 1943:Hou Lianhai 1676:P. sinensis 1539:Paul Sereno 1513:P. sinensis 1493:P. sinensis 1470:P. sinensis 1331:sedimentary 1319:P. sinensis 1268:P. sinensis 1184:P. sinensis 1072:instead of 1046:Haratologay 940:jugal bones 833:gastroliths 715:Triceratops 650:ceratopsian 509:P. amitabha 330:P. sinensis 8837:Categories 8685:See also: 8392:Torosaurus 8308:Spiclypeus 8158:Agathaumas 8071:see below↓ 7891:Cerasinops 7679:Stenopelix 7613:Ceratopsia 7600:Ceratopsia 7568:see below↓ 7559:Ceratopsia 7471:Dinosauria 7438:Ceratopsia 6633:(1). 132. 6549:: 535–544. 5509:: 663–668. 5132:: 801–812. 4658:: 349–360. 4636:: 783–788. 4586:Bohlin, B. 4376:References 4308:biochron. 4203:, a large 4175:Fossil of 4047:fossilized 3867:with long 3857:cathemeral 3428:Hai-Lu You 3407:skeleton, 2936:Ceratopsia 2923:Stegoceras 2867:archosaurs 2823:type genus 2669:neck frill 2661:acetabulum 2626:homologous 2610:neck frill 2498:Skulls of 2433:Tianyulong 2352:homologous 2303:integument 2261:See also: 2223:predentary 1941:, honours 1541:described 1525:P. osborni 1505:Zhao Xijin 1376:P. osborni 1372:P. osborni 1360:P. osborni 1353:hatchlings 1295:Zhao Xijin 1272:P. osborni 1260:P. osborni 1244:P. osborni 958:, and the 908:premaxilla 853:Cretaceous 698:Tianyulong 657:Cretaceous 396:Suteethorn 244:Ceratopsia 180:Dinosauria 7454:Kingdom: 7185:27 August 7096:128781816 6006:199571348 5998:2246/6953 5664:129260211 5553:128771310 5485:237336322 5425:(1): 62. 5069:129687832 4742:: 89–107. 4617:: 53–159. 4423:2246/3267 4282:Barremian 4242:Ordosemys 4167:Predation 4140:infection 4128:pathology 4118:Pathology 4084:precocial 4039:placental 4031:marsupial 3963:However, 3766:allometry 2863:evolution 2618:palpebral 2592:underbite 2472:umbilicus 2138:in size ( 2057:from the 1951:You Hailu 1909:words 紅 ( 1730:Barremian 1710:vertebrae 1582:from the 1517:P. youngi 1509:P. youngi 1465:as well. 1315:P. youngi 1311:P. youngi 1036:skull of 1011:vertebrae 863:. In the 785:east Asia 766:hatchling 392:Buffetaut 153:Kingdom: 147:Eukaryota 8731:Wikidata 8697:Category 8687:Timeline 8193:Polyonax 8179:Dysganus 8172:Ceratops 7735:Aquilops 7462:Chordata 7460:Phylum: 7456:Animalia 7276:15650737 7180:phys.org 7042:23811819 7018:: 2079. 6945:33253407 6937:21493820 6864:25494182 6824:PLOS ONE 6805:16901832 6756:89051352 6659:35672741 6608:89156313 6528:12955841 6484:27641767 6375:27641767 6318:33472049 6266:18182372 6197:17781405 6189:12435037 5933:17781405 5925:12435037 5824:15356619 5769:19535376 5715:55251322 5617:23950887 5577:PLOS ONE 5215:84569578 5155:: 71–73. 4588:(1953). 4575:: 1–554. 4519:: 1–678. 4343:See also 4284:through 4276:bearing 4217:Mesozoic 4148:necrosis 3945:pronated 3923:Mounted 3869:chevrons 3816:. Large 3814:endocast 3572:P. major 3403:Mounted 3120:Aquilops 2895:Aquilops 2587:fenestra 2582:mandible 2520:P. major 2452:follicle 2372:collagen 2356:theropod 2092:Amitabha 1872:P. major 1860:P. major 1841:P. major 1571:fossil, 1384:P. tingi 1368:P. tingi 1256:P. tingi 1248:P. tingi 1211:Shandong 1137:Kemerovo 1066:P. tingi 924:holotype 877:skeleton 861:Mongolia 857:Tertiary 807:Holotype 792:biochron 743:Aquilops 685:Thailand 677:Mongolia 653:dinosaur 641:") is a 557:, & 528:Synonyms 250:Family: 167:Chordata 163:Phylum: 157:Animalia 143:Domain: 8805:4126864 8792:1000094 8779:4823245 8766:4532049 8737:Q132672 8587:Spinops 7905:Gremlin 7693:Yinlong 7344:Bibcode 7284:2306428 7256:Bibcode 7214:Bibcode 7076:Bibcode 7020:Bibcode 6917:Bibcode 6909:Science 6855:4262212 6832:Bibcode 6796:1635516 6736:Bibcode 6650:9172161 6578:Bibcode 6508:Bibcode 6475:5049543 6454:Bibcode 6366:5049543 6345:Bibcode 6296:Bibcode 6257:2596897 6169:Bibcode 5905:Bibcode 5866:Bibcode 5832:4413450 5804:Bibcode 5760:2842669 5644:Bibcode 5608:3739782 5585:Bibcode 5533:Bibcode 5427:Bibcode 5387:1973589 5367:Bibcode 5255:Bibcode 5195:Bibcode 5149:Oryctos 5092:Bibcode 5049:Bibcode 5005:Bibcode 4270:Siberia 4249:, China 3905:gizzard 2950:Yinlong 2859:nostril 2832:Yinlong 2821:is the 2725:ischium 2512:dentary 2508:maxilla 2476:amniote 2448:turkeys 2400:patagia 2323:Germany 2282:R 4970) 2239:derived 2227:keratin 2219:rostral 2211:profile 2063:Montana 2017:P. houi 2005:P. houi 1997:P. houi 1991:within 1983:P. houi 1979:H. houi 1947:curated 1939:H. houi 1879:P. houi 1834:H. houi 1818:H. houi 1702:Xu Xing 1489:Beijing 1195:Laiyang 1141:Siberia 777:biology 746:, from 734:derived 721:Yinlong 683:, and 669:species 647:extinct 514:Napoli 413:Russell 270:Genus: 7282: 7274: 7248:Nature 7094: 7040: 6970: 6943: 6935: 6862: 6852: 6803: 6793: 6754: 6657: 6647: 6606: 6526: 6482: 6472: 6373: 6363: 6316: 6264: 6254: 6211:Nature 6195: 6187: 6122:Nature 6038: 6034:–613. 6004: 5931: 5923: 5830: 5822: 5796:Nature 5767: 5757: 5713: 5662: 5615: 5605: 5551: 5483: 5385: 5213: 5067: 4934: 4930:–699. 4901: 4897:–516. 4782: 4778:–210. 4708: 4704:–493. 4286:Albian 4260:. All 4144:fibula 4104:burrow 4001:, AMNH 2882:et al. 2871:evolve 2715:. The 2687:, and 2640:, and 2580:. The 2459:cloaca 2396:cloaca 2363:dermis 2340:dorsal 2330:scales 2084:et al. 1923:sauros 1736:was a 1463:pelvis 1445:extant 1345:stages 1342:Albian 1338:Aptian 1334:strata 1163:, and 1133:Moscow 922:. 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