Psittacosaurus - Knowledge

122: 2819: 8118: 3899: 814: 4247: 3411: 1576: 8124: 4849: 1190: 832: 4005: 3809: 4117:. 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 2300: 8674: 1041: 146: 4183: 2284: 2201: 3922:

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 If the jaws were aligned, the beaks could be used to crop objects, but if the lower jaw was retracted so that the lower beak was inside the upper beak, the jaws may have served a nutcracking function.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.

4077: 3931: 1428: 2114: 1897: 2465:, 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. 2811: 2502: 8704: 2429: 3753: 4101: 8680: 1631:. 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 4362: 7407: 1759:, 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. 4028:(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. 1601:, 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. 3913:

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

4097:. 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. 3775:. 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 1560:

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,

2353:(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 2659:

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,

2228:(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 2440:

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.).

1012:, 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 1819:, 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. 4124:

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

4326:, 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 2742:, 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 2380:

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.).

1510:, 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 4088:

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.

1442:, 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 1450:

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

1793:. 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 1138:

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

6572: 1362:, 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 1732: 1088: 775:

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

2343:. 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 2401:, 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 2197:('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. 1731:

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

3801:, 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 4093:

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

1865:, 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 2056:. 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 2472:, 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. 1415:, 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 1404: 6737:

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".

2349:. 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 5512:

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.

2256:(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 8923: 2619:. 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 4108:

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

8797: 1627:. 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 8913: 2541:

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).

4174:, 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. 4639:

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

2328:, 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 5902:

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.

121: 3791:. 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, 2489:). Because the specimen is close to sexual maturity, it is likely that the umbilicus probably retained throughout this individual's life and that 3954:

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

1377:, but noted it was tentative because of the presence of multiple valid psittacosaur species in Inner Mongolia. Young also described the species 8928: 8908: 3429:

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

957:, a general dissimilarity in the skeletons, and wide geographic separation of the two specimens, Gregory suggested in correspondence that the 8117: 6982: 3882:(and with the bristles on the tail interpreted as possibly skin-covered, forming a fin), providing a propulsive surface; and the presence of 3967:

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,

7439: 917:. 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 706:

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

2686:(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 133: 4350:, suggests that the lower beds are younger, approximately 123.2 mya, while agreeing with an age of 122 mya for the upper beds. 890:

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

2818: 5363:"Biostratigraphy and palaeoenvironment of the dinosaur-bearing sediments in Lower Cretaceous of Mazongshan area, Gansu Province, China" 8123: 5463:

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

859: 825: 1755:. However, more recent authors have noted that it can be distinguished by its proportionally long snout compared to other species of 8883: 6050: 4946: 4913: 4794: 4720: 1317: 633: 1781:. Two other nearby localities were explored in the 1990s, one of which produced several complete skeletons. This species was named 1685:, this species was discovered in the Eijnhoro Formation. Sereno (2010) found the species as described to be indistinguishable from 2369:

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

8697: 4380: 5867:(Dinosauria: Ceratopsia) specimen from the Yixian Formation of western Liaoning, China: the first pathological psittacosaurid". 5961: 5192:

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

2891:. The below cladogram is from their analysis, placing the genus as one of the most primitive ceratopsians. The authors (Farke 941:, AMNH 6253, included a nearly complete skeleton found articulated, and partial remains of the skull. While Osborn considered 8888: 7211:

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

4053: 1446:, containing only a single known species. The difference is most likely due to artifacts of the fossilisation process. While 2666:

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

2639:. The jugal has extremely prominent 'horns' and may contact the premaxilla, both features also seen in the possibly related 1873:

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.

1877:, and other features. However, a 2013 study utilising morphometric analysis showed that the supposed differences between 145: 8903: 8898: 8873: 8868: 8858: 8673: 6243:"A unique cross section through the skin of the dinosaur Psittacosaurus from China showing a complex fibre architecture" 4703:

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

2065: 1583: 1024:, and other details of the skull and skeleton. Osborn also referred the specimen AMNH 6261 from the Oshih Formation to 3898: 1454:

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

813: 3982:, ranging in age from less than a year old to ten-year-old adults, Qi Zhao from the University of Bristol found that 1472:

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

4246: 2579:. Because of the flared cheeks, the skull is actually wider than it is long. A smaller 'horn' is present behind the 3978:

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

6831:"A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia" 1885:

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

1216:. Of this material, the nearly complete skeleton and skull IVPP V738 was described as the type of the new species 8878: 4503:

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

2461:; these structures differ from feathers in that they are unbranched, heavily cornified and do not develop from a 2244:

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

1736: 1712: 1575: 565: 454: 7186: 5584:"Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics" 4347: 6918:

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

6429: 5746:"A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull" 4226:

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

2782:. Overall, this species is thought to exhibit several primitive characteristics compared to other species of 2137:—can reach 2 metres (6.5 ft) in length. The maximum adult body weight was most likely over 20 7648: 4257: 2722:, although it is less pronounced than in those species. The material appears to be roughly the same size as 2601:, seen in other species, and the entire lower jaw is bowed outwards, giving the animal the appearance of an 1739:, which have not been precisely dated, although there is some evidence that they were deposited in the late 1092: 1067:

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

2361:. The study stated that, "at present, there is no convincing evidence which shows these structures to be 1790: 1099:, and fragments of vertebrae and limbs were found in the same locality, with the tooth being referred to 471: 8893: 8823: 8707: 7557: 4065: 3840:, with one individual preserving them likely contracted postmortem, but if they are similar to those of 2837: 2402: 2069: 1786: 1735:(IVPP), and several fragments have been lost, including all of the teeth. The remains were found in the 1253:

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

8679: 2702:. The complete type skull, probably adult, is 13.7 centimetres (5.5 in) long. The dentary of 2299: 1332:, but separated them to bring the count of members of Psittacosauridae to one genus and five species. 8771: 7354: 7266: 7224: 7086: 7030: 6927: 6842: 6746: 6609: 6588: 6571:

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

6518: 6464: 6355: 6306: 6179: 5915: 5876: 5814: 5654: 5595: 5543: 5437: 5377: 5265: 5205: 5102: 5059: 5015: 4235: 4188: 2670:, one of the three bones of the pelvis, also bears a characteristically long bony process behind the 2405:. The specimen also had dense clusters of pigment on its shoulders, face (possibly for display), and 2261: 1620: 1464: 1309: 1201: 1163: 1127: 1123: 1108: 1029: 1009: 930: 914: 906: 851: 5414:

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

4222:

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

1861:

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

8762: 7813: 7425: 7389: 6042: 4938: 4375: 3851: 2864: 2734:

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

2623:, which is longer than any other species, at 15 to 18% of skull length. A very striking feature of 2514: 2273: 2220:

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

2061: 1968:

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

1812: 1616: 1594: 1033: 406: 5464: 2453:. Similar, non-feather-derived bristles are found in a few extant birds such as the "horn" on the 2336:. It was described while awaiting repatriation; previous repatriation attempts were unsuccessful. 1965: 1389:. You and Dodson (2004) followed this in a table, but Sereno regarded both species as synonyms of 569: 491: 8533: 8483: 7915: 7309: 7290: 7102: 6999: 6951: 6762: 6614: 6203: 6012: 5939: 5838: 5721: 5670: 5559: 5491: 5393: 5221: 5158:

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

5075: 5050:(Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northeastern China". 5006:(Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northwestern China". 4327: 4284: 3419: 2926: 2636: 2597: 2462: 2362: 2329: 2290: 2053: 2048:

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

1977: 1953: 1669: 1491: 1213: 1056: 994: 891: 538: 140: 7151: 4141:. The specimen in question, consisting of a complete adult skeleton and tentatively assigned to 3438: 2674:(hip socket). An adult femur has a published length of about 16 centimetres (6.3 in). 2409:(which may have had an antimicrobial function, though this has been disputed), as well as large 8828: 7411: 5645:(Dinosauria: Psittacosauridae) from the Lower Cretaceous of Western Liaoning Province, China". 4905: 4830: 4786: 4712: 4400: 1961: 1040: 561: 8810: 8802: 8616: 8554: 8517: 7991: 7878: 7282: 7048: 6978: 6943: 6870: 6811: 6665: 6534: 6490: 6381: 6324: 6272: 6195: 6046: 5931: 5830: 5775: 5623: 4942: 4909: 4790: 4716: 4304: 4182: 4090: 3879: 3291: 2896: 2354: 2325: 1589:

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

1385:. It is based on several skull fragments. He later synonymised the two species under the name 1359: 675: 8815: 6782:"A basal ceratopsian with transitional features from the Late Jurassic of northwestern China" 2836:

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

8646: 8444: 8269: 7971: 7666: 7381: 7362: 7274: 7232: 7166: 7129: 7094: 7038: 6935: 6900: 6860: 6850: 6801: 6793: 6754: 6719: 6655: 6645: 6604: 6596: 6526: 6480: 6472: 6371: 6363: 6314: 6262: 6254: 6187: 6114: 6084: 6034: 6004: 5996: 5923: 5884: 5822: 5765: 5757: 5711: 5662: 5613: 5603: 5551: 5483: 5445: 5385: 5343: 5273: 5213: 5110: 5067: 5023: 4984: 4930: 4897: 4778: 4704: 4555: 4428: 4367: 4276: 2847: 2774:. The jugal bones flare outwards widely, making the skull wider than it is long, as seen in 2628: 2350: 2321: 2200: 1937: 1917: 1816: 1665: 1224:. Yang also assigned 11 other specimens to the taxon, considering it to be the most diverse 974: 895: 589: 41: 5131:

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

4877:

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

2283: 1988:. He did not synonymise the two species because of difficulties with the holotype skull of 8540: 8492: 8451: 8387: 8290: 8241: 7943: 7867: 7822: 7696: 7682: 7641: 7515: 7499: 5692: 4559: 4331: 4076: 3930: 3235: 2991: 2916: 2876:

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

2790:

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

2683: 2513:

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

2454: 2340: 2252:

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

2225: 2194: 2102: 1778: 1774: 1518:

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

1443: 1427: 875: 238: 7382: 6035: 6033:

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

4931: 3858:

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

17: 7358: 7270: 7228: 7133: 7090: 7034: 6931: 6846: 6750: 6592: 6522: 6468: 6359: 6310: 6183: 5919: 5880: 5818: 5798:

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

5658: 5599: 5547: 5441: 5381: 5269: 5209: 5106: 5063: 5019: 8547: 8506: 8437: 8424: 8395: 8380: 8350: 8311: 8297: 8214: 8175: 8054: 7964: 7929: 7922: 7802: 7752: 7675: 6865: 6830: 6806: 6781: 6758: 6723: 6660: 6633: 6553: 6485: 6452: 6376: 6343: 6267: 6242: 6088: 5989:, a new species of ceratopsian dinosaur from the Ondai Sayr locality, central Mongolia" 5770: 5745: 5666: 5618: 5583: 5332:(Dinosauria: Ceratopsia) from the Early Cretaceous Yixian Formation, Liaoning, China". 5196:

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

4167: 4113:

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

3859: 3836:

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

3833: 3828: 3161: 3008: 2564: 2398: 2018:

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

1940:

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

1896: 1794: 1724: 1633: 1612: 1273:. Following his new breakdown of species, Yang described the distribution of the genus 1220:, which was found in a red layer 10 mi (16 km) northwest of Rongyang City in 1179: 1134:. In 1946 they discovered a new locality, Ulan Osh, where a disarticulated specimen of 1079:, was named for partial lower jaws and teeth, which Young only tentatively referred to 1072: 1064: 1060: 990: 740: 402: 346: 222: 7251: 7067: 6160: 5799: 5362: 2810: 2501: 2393:

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

921:. In the same paper, Osborn also described another new taxon he considered similar to 913:, describing its parrot-like beak on the suggestion of fellow American paleontologist 878:

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

8847: 8625: 8604: 8574: 8565: 8465: 8359: 8304: 8283: 8255: 8248: 8234: 8227: 8033: 8022: 8015: 7957: 7950: 7936: 7894: 7829: 7795: 7766: 7719: 7106: 7098: 6118: 6016: 5674: 5563: 5495: 5079: 4898: 4779: 4705: 4596: 4146: 3991:

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

3867: 3842: 3797: 3779:

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

3430: 3268: 3218: 3092: 2880:. It is considered highly unlikely that the fifth digit or antorbital fenestra would 2458: 2449: 2357:, they gave off the same fluorescence as scales, providing the possibility they were 1929: 1112: 970: 966: 791: 758: 744: 79: 7013:

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

6975:

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

6955: 6766: 6618: 6207: 5943: 5725: 5328:

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

5225: 4929:

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

4509:

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

3971:

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

3752: 2428: 2113: 8639: 8590: 8583: 8499: 8472: 8458: 8366: 8339: 8332: 8325: 8276: 8262: 8154: 8141: 8072: 8061: 8046: 8008: 8000: 7982: 7887: 7853: 7836: 7788: 7781: 7737: 7542: 7490: 7294: 5842: 5397: 5256:

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

5071: 5027: 4546:

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

4100: 3306: 3178: 3106: 2900: 2855: 2727: 2667: 2345: 2249: 2217: 1998: 1945: 1657: 1562: 1455: 1399: 1355: 1304:

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

1154:

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

982: 784: 423: 300: 206: 7366: 7236: 5984: 5888: 5555: 2563:(cheek) bone on the outside of the skull. The jugals flare out sideways, forming ' 1908:

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

7215:

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

6904: 6855: 5608: 5347: 4971:

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

4283:

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

2525:(the tooth-bearing bone of the lower jaw), although it is not as prominent as in 2006:. Sereno's hypothesis was supported by a morphometric study in 2013, which found 8756: 8632: 8526: 8409: 8373: 8196: 7908: 7773: 5361:

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

5334: 4507:)". In Ryan, Michael J.; Chinnery-Allgeier, Brenda J.; Eberth, David A. (eds.). 4308: 4215: 4210: 3906: 3883: 3442: 2795: 2584: 2415: 1549: 1468:

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

1341: 725: 363: 54: 6973:". In Ryan, Michael J.; Chinnery-Allgeier, Brenda J.; Eberth, David A. (eds.). 6650: 4311:

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

2447:, and the sparsely distributed elongated broad filamentous feathers (EBFFs) of 2320:

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

2097:

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

1530:

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

8402: 8318: 8168: 7901: 7689: 7623: 7610: 7569: 7448: 6476: 6367: 6319: 6294: 6191: 5927: 5863:

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

5217: 4357: 4300: 2946: 2933: 2833: 2679: 2671: 2620: 2556: 2443: 2421:

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

2313: 2138: 1677: 1538:, You and Dodson (2004) listed it as valid in a table, but not in their text. 1515: 1305: 950: 918: 863: 843: 708: 667: 660: 384: 254: 99: 64: 8747: 7015:"Histology and postural change during the growth of the ceratopsian dinosaur 5983:

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

4145:, was found in the lower beds of the Yixian Formation. There is no sign of a 2850:. While Psittacosauridae was an early branch of the ceratopsian family tree, 6977:. Bloomington and Indianapolis: Indiana University Press. pp. 328–339. 6939: 4582:

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

4292: 4252: 4223: 4150: 4138: 4094: 4049: 4041: 4032: 3776: 2881: 2877: 2873: 2602: 2052:

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

1740: 1363: 1021: 795: 776: 157: 104: 48: 7310:"Juvenile-only clusters and the behaviour of the Early Cretaceous dinosaur 7286: 7052: 6947: 6874: 6815: 6797: 6669: 6538: 6494: 6385: 6328: 6276: 6258: 6229: 6199: 5935: 5834: 5779: 5761: 5627: 5487: 5389: 5298:

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

4741:

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

1960:

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

1320:. Known for a complete skull, partial vertebral series and partial pelvis, 7406: 7187:"Paleontologists describe a possible dinosaur nest and young 'babysitter'" 7171: 6710:

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

6161:"Bristle-like integumentary structures at the tail of the horned dinosaur 6075:

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

5716: 5449: 2221: 8741: 8203: 8189: 8182: 7745: 7481: 7472: 6140: 6105:

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

4511:. Bloomington and Indianapolis: Indiana University Press. pp. 21–58. 4227: 4158: 3955: 3824: 3130: 2905: 2592: 2485:(belly button) known from a non-avian dinosaur (the oldest known from an 2410: 2382: 2366: 2236:

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

1720: 1598: 1557: 1495: 1221: 1147: 1044: 934: 887: 883: 871: 867: 817: 802: 753: 695: 687: 663: 190: 177: 94: 89: 74: 69: 59: 7278: 6969:

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

4170:

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

1847:

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

1419:

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

682:-rich non-avian dinosaur genus. Up to 12 species are known, from across 8789: 8597: 7759: 7703: 7152:"Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur 7068:"Social behaviour and mass mortality in the basal ceratopsian dinosaur 7043: 7014: 6634:"Oldest preserved umbilical scar reveals dinosaurs had 'belly buttons'" 6600: 4423:

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

4343: 4280: 3915: 2960: 2869: 2842: 2798:, a depression on the postorbital-jugal contact, and enamel thickness. 2735: 2522: 2518: 2486: 2358: 2333: 2237: 2073: 1957: 1499: 1344: 1205: 1151: 787: 731: 679: 657: 109: 84: 6401:"Scientists reveal most accurate depiction of a dinosaur ever created" 5046:

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

4334:, tens of millions of years outside of the expected temporal range of 3950:

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

3886:, interpreted as ballast. They further suggested that some species of 3854:

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

1827:, which was found in the same beds. It is potentially synonymous with 1028:, so the teeth of the two taxa could be compared. It was mentioned in 7466: 6780:

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

6530: 6220:

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

6008: 4831:"New psittacosaurid highlights skull enlargement in horned dinosaurs" 4433: 4315:, leading to the definition of this time period in the region as the 4296: 4238:, the production of more numerous offspring to counteract this loss. 4200:

Another fossil from the Yixian Formation provides direct evidence of

4154: 4114: 4057: 2469: 2406: 2373: 1751:, with no unique features that separate it from any other species of 1473: 1352: 1348: 1143: 902: 898: 703: 691: 649: 646: 167: 8718: 6706:

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

5826: 5277: 5114: 4988: 3433:

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

2133:

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

6829:

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

6000: 5465:"Femoral histology and growth patterns of the ceratopsian dinosaur 4711:(2nd ed.). Berkeley: University of California Press. pp. 2372:

In 2008, another study was published describing the integument and

2289:

Specimen with preserved tail integument and pigmentation (specimen

1522:(a partial skeleton and skull) was discovered in the same rocks as 1233:. Following similar conclusions to Rozhdestvensky, Yang considered 743:

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

735:. Once in its own family, Psittacosauridae, with other genera like 4975:

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

4620:

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

4245: 4181: 4171: 4162: 4099: 4075: 4003: 3929: 3897: 3807: 3751: 3409: 2817: 2809: 2739: 2560: 2542: 2521:(an upper jaw bone). A flange is present on the lower edge of the 2500: 2482: 2427: 2253: 2241: 2199: 2130: 2112: 2022:

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

1895: 1574: 1426: 1188: 1039: 879: 830: 812: 683: 653: 7000:"How 'parrot dinosaur' switched from four feet to two as it grew" 6131:

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

5582:

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

4399:

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

4299:

stages of the Early Cretaceous, or approximately 125 to 105

3850:

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

2682:

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

1769:

Beginning in the 1950s, Russian paleontologists began excavating

1619:, described a partial upper and lower jaw from the Aptian-Albian 765:

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

8776: 4205: 4080:

Group of six juveniles that died together – specimen IVPP V14341

4045: 2643:. There is a flange on the dentary of the lower jaw, similar to 1689:, another small species, but suggested that additional study of 1460: 1107:

material from possibly the same locality was described later in

1096: 779:

through to adult, which has allowed several detailed studies of

671: 8722: 8139: 7608: 7459: 7421: 4230:

mammals preying on live dinosaurs. Heavy predation on juvenile

1000:

Osborn published an additional description of the specimens of

7120:

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

5962:"MSU, Mongolian paleontologists find 67 dinosaurs in one week" 4773:

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

4137:

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

4064:

by using growth ring counts suggest that the longevity of the

3958:

nor generate propulsive force for locomotion, suggesting that

3870:, active throughout the day and for short intervals at night. 2580: 1693:

might reveal diagnostic features. He provisionally designated

1103:

and the remainder of the material being uncertain. Additional

7417: 7250:

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

1727:, near the border with Inner Mongolia. This species is named 1091:

as IVPP RV31039 and IVPP RV31040 respectively, come from the

905:

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

6632:

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

3866:

and modern birds and reptiles suggest that it may have been

619: 4338:, most recent work dates it to the Early Cretaceous. Using 622: 610: 604: 6159:

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

6071:

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

4402:

The dinosaur book: the ruling reptiles and their relatives

2909:

are from Asia, meaning the group likely originated there.

1733:

Institute of Vertebrate Paleontology and Paleoanthropology

1672:

with seven other individuals. Russell and Zhao also named

1561:

Xinjiang. These specimens come from the upper part of the

1089:

Institute of Vertebrate Paleontology and Paleoanthropology

1055:

Following the discovery of material of psittacosaurids in

1020:, including the number of teeth, the number of pre-caudal 794:

has led to the labelling of Lower Cretaceous sediments of

4104:

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

2609:

can reach 11.5 centimeters (4.5 in) in length.

2365:

to the structurally different integumentary filaments of

1823:

was contemporaneous with another psittacosaurid species,

1715:, another Chinese paleontologist, named a new species of 909:

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

598: 5695:

New data on cranial anatomy of the ceratopsian dinosaur

2397:

preserved with integument indicated that the animal was

1289:

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

6786:

Proceedings of the Royal Society B: Biological Sciences

6247:

Proceedings of the Royal Society B: Biological Sciences

4813:(in Chinese). Beijing: Geology Press. pp. 123–136. 3771:

would have been similar to other ceratopsians with low

2786:, which is consistent with its greater geological age. 1158:. This material was described by Soviet paleontologist 7308:

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

929:, which was found in the same expedition but from the 2868:, an opening in the skull between the eye socket and 1743:

through Aptian stages. Sereno suggested in 2000 that

1241:, but retained the species as separate giving former 862:

to discover fossils and geologic formations from the

634: 625: 616: 607: 595: 592: 5187: 5185: 5183: 5181: 5179: 5177: 5175: 5173: 4829:

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

4218:

mammal, is preserved with the remains of a juvenile

723:

was one of the earliest ceratopsians, but closer to

601: 515: 501: 481: 461: 444: 430: 413: 391: 373: 353: 336: 307: 8731: 8615: 8573: 8564: 8516: 8482: 8423: 8349: 8213: 8152: 8071: 8032: 7990: 7981: 7877: 7851: 7812: 7717: 7665: 7621: 7568: 7541: 7514: 6691:: Two Lower Cretaceous iguanodonts from Mongolia". 6293:Vinther, J.; Nicholls, R.; Kelly, Diane A. (2021). 5641:You, Hailu; Xu, Xing (2005). "An adult specimen of 4966: 4964: 4962: 4960: 4958: 4603:

The Sino-Swedish Expedition Publications 37, 113 pp

4459:: Two Lower Cretaceous iguanodonts from Mongolia". 4157:. The bone exhibits a large round pit, evidence of 2862:had only four digits on the hand. In addition, the 1719:in 1997, based on a complete skull with associated 613: 5251: 5249: 5247: 5245: 5243: 5241: 5239: 5237: 5235: 5154:Buffetaut, E.; Suteethorn, V. (2002). "Remarks on 4904:. Cambridge: Cambridge University Press. pp. 4785:. Cambridge: Cambridge University Press. pp. 3787:is 0.31, significantly higher than genera such as 2814:Reconstructed skeletons of an adult with juveniles 1438:Seventeen species have been referred to the genus 5739: 5737: 5735: 5416:(in Russian). Tomsk: GalaPress. pp. 363–366. 5041: 5039: 5037: 4824: 4822: 4820: 4781:Dinosaur Systematics: Perspectives and Approaches 4777:)". In Carpenter, Ken; Currie, Philip J. (eds.). 4698: 4696: 4578:Sereno, P.C. (1987). "The ornithischian dinosaur 2655:. It can be told apart from the other species of 2631:bones. Similar horns found on the postorbital of 2044:These specimens are generally all referred to as 1773:remains at a locality near Shestakovo village in 1115:, who considered the remains to likely belong to 858:took part in the Third Asiatic Expedition of the 7072:(Early Cretaceous, People's Republic of China)"" 7066:Zhao, Q.; Barrett, P. M.; Eberth, D. A. (2007). 5691:You, Hai-Lu; Tanoue, Kyo; Dodson, Peter (2008). 5686: 5684: 5430:Geological Society, London, Special Publications 5126: 5124: 4694: 4692: 4690: 4688: 4686: 4684: 4682: 4680: 4678: 4676: 4342:, a team of Chinese scientists dated the lowest 3795:behaviour could have been as complex as that in 2750:, with a proportionately longer skull and tail. 2240:to provide a sharp cutting surface for cropping 2185:, although neither is significantly larger than 1208:, in which he described multiple discoveries of 1071:, distinguished by its small size and lack of a 6066: 6064: 6062: 5793: 5791: 5789: 5744:Sereno, Paul C.; Xijin, Zhao; Lin, Tan (2010). 5529: 5527: 5507: 5505: 5323: 5321: 5319: 5317: 5315: 5313: 5311: 5309: 2567:' proportionally wider than in any other known 1723:and a forelimb. This material was recovered in 5955: 5953: 2770:. There is a fossa in front of the eye, as in 7433: 6886: 6884: 6100: 6098: 6028: 6026: 5858: 5856: 5854: 5852: 5469:from the Early Cretaceous of Western Siberia" 5302:. Beijing: China Ocean Press. pp. 48–67. 4890: 4888: 4886: 4879:. Beijing: China Ocean Press. pp. 75–80. 4870: 4868: 4866: 4864: 4862: 4860: 4858: 4768: 4766: 4764: 4762: 4760: 4736: 4734: 4732: 4498: 4496: 4494: 4492: 4490: 4275:fossils discovered so far have been found in 3938:skeleton casts in upright and crouching poses 2224:in some species. The portion in front of the 1565:, which is regarded as Aptian-Albian in age. 1204:, Yang published a paper on the dinosaurs of 8: 7336: 7334: 6453:"3D Camouflage in an Ornithischian Dinosaur" 6344:"3D Camouflage in an Ornithischian Dinosaur" 5800:"Parental care in an ornithischian dinosaur" 4573: 4571: 4569: 4488: 4486: 4484: 4482: 4480: 4478: 4476: 4474: 4472: 4470: 4446: 4444: 4418: 4416: 4414: 4412: 3942:Studies by Phil Senter in 2007 conducted on 3740:In 2005, Zhou and colleagues suggested that 2260:, but these are thought to be an example of 1936:("lizard"). This name refers to the ancient 6295:"A cloacal opening in a non-avian dinosaur" 6154: 6152: 6150: 6148: 5577: 5575: 5573: 5300:Sino-Japanese Silk Road Dinosaur Expedition 4900:The Age of Dinosaurs in Russia and Mongolia 4656: 4654: 4615: 4613: 4611: 4609: 4548:Bulletin of the Geological Society of China 4541: 4539: 4537: 4153:can be seen near the midpoint of the right 2858:or primitive trait, whereas all species of 2738:bone of the pelvis is also longer than the 2248:skulls share several adaptations with more 1265:, but not separate from each other, making 949:separate based on the lack of horns on the 8719: 8570: 8429: 8219: 8160: 8149: 8136: 8038: 7987: 7859: 7729: 7725: 7633: 7629: 7618: 7605: 7547: 7520: 7511: 7456: 7440: 7426: 7418: 2390:and offered protection against predators. 2129:vary in size and specific features of the 1956:, a professor at the IVPP in Beijing, who 1811:, named in 2006 by Chinese paleontologist 1548:In 1988, Zhao and American paleontologist 1403:, however. The front half of a skull from 1281:was the only species known from Shandong; 1122:The Soviet Expeditions into Mongolia from 981:, which he considered possibly related to 120: 31: 7252:"Large Mesozoic mammals fed on dinosaurs" 7170: 7042: 6864: 6854: 6805: 6712:Zoological Journal of the Linnean Society 6659: 6649: 6610:1983/029c668f-08b9-45f6-a0c5-30ce9256e593 6608: 6484: 6375: 6318: 6266: 6077:Zoological Journal of the Linnean Society 5769: 5715: 5617: 5607: 5289: 5287: 4432: 2778:. Widely flared jugals are also found in 2595:(lower jaw) lacks the hollow opening, or 2505:Restored heads of eight species, to scale 751:are all from Asia, with the exception of 7122:Annual Review of Ecology and Systematics 5135:from the Early Cretaceous of Thailand". 3445:in 2010. The middle one is shown below. 2840:to almost all known ceratopsians except 2481:, and found that it preserves the first 2468:A 2021 study of SMF R 4970 examined its 1623:of Thailand in 1992, giving it the name 1381:in the same 1931 report which contained 1369:In a 2010 review, Sereno again regarded 993:as the only member of the new subfamily 790:. The abundance of this dinosaur in the 8924:Multispecific non-avian dinosaur genera 7145: 7143: 5964:. Montana State University News Service 4391: 1486:In the 1950s, a new Chinese species of 1212:from a collection of localities of the 961:specimen could represent a juvenile of 334: 6998:University of Bristol (28 June 2013). 5294:Xu, Xing (1997). "A new psittacosaur ( 5002:Sereno, Paul C.; Xijin, Zhao (1988). " 4937:. San Diego: Academic Press. pp. 2706:has a flange similar to that found in 2161:), while others are somewhat smaller ( 2030:, which would normally have priority. 1992:, instead considering new combination 1660:and Zhao in 1996. The first was named 7345:biochron, Early Cretaceous of Asia". 6399:Panciroli, Elsa (14 September 2016). 6288: 6286: 5960:Boswell, Evelyn (13 September 2006). 4560:10.1111/j.1755-6724.1932.mp11003005.x 4405:. New York: McGraw-Hill. p. 153. 3873:Ford and Martin (2010) proposed that 2438:laser-stimulated fluorescence imaging 2216:is highly modified compared to other 1328:was considered to be most similar to 1075:on the parietal. The second species, 965:, based on similarities in size, the 747:forms. The genera closely related to 7: 8914:Taxa named by Henry Fairfield Osborn 3759:skull LHPV 1 from the left and above 7134:10.1146/annurev.es.05.110174.001545 6428:. 14 September 2016. Archived from 5198:Journal of Systematic Palaeontology 4020:have been found. The smallest is a 3890:were more terrestrial than others. 3646: 3622: 3598: 3574: 3524: 3517: 3467: 3460: 3448: 3284: 3260: 3210: 3203: 3153: 3146: 3122: 3098: 3045: 3033: 2983: 2976: 2952: 2922: 2912: 2555:and have less teeth. Uniquely, the 2305:Body details of specimen SMF R 4970 1831:; Sereno (2010), who proposed that 1526:and appears to be very similar, so 1407:in Inner Mongolia was described as 678:. It is notable for being the most 8864:Early Cretaceous dinosaurs of Asia 6759:10.1111/j.1755-6724.2003.tb00105.x 6724:10.1111/j.1096-3642.2000.tb02201.x 6089:10.1111/j.1096-3642.2000.tb02201.x 5750:Proceedings of the Royal Society B 5667:10.1111/j.1755-6724.2005.tb00879.x 5258:Canadian Journal of Earth Sciences 5095:Canadian Journal of Earth Sciences 5052:Journal of Vertebrate Paleontology 5008:Journal of Vertebrate Paleontology 4977:Canadian Journal of Earth Sciences 4026:American Museum of Natural History 2903:with the exception of their genus 2583:, at the contact of the jugal and 1301:was possibly known from Kemerovo. 860:American Museum of Natural History 826:American Museum of Natural History 25: 5653:(2) (English ed.): 168–173. 4279:sediments in Asia, from southern 2895:) noted that all taxa outside of 2635:are not as pronounced but may be 1463:and can only be evaluated from a 1393:; a table in the latter reported 1318:Beijing Museum of Natural History 1247:Psittacosaurus protiguanodonensis 1087:. Both specimens, stored in the 842:" holotype. Note the presence of 134:Children's Museum of Indianapolis 8703: 8702: 8678: 8672: 8122: 8116: 7405: 7099:10.1111/j.1475-4983.2007.00709.x 6119:10.1111/j.1469-7998.2007.00329.x 4847: 4381:Timeline of ceratopsian research 4360: 4196:remains preserved in its stomach 4068:ceratopsian was 10 to 11 years. 4044:mammals, but slower than modern 2615:is the largest-known species of 2517:, on the outside surface of the 2339:Most of the body was covered in 2298: 2282: 1900:Juveniles formerly described as 1857:One nearly complete skeleton of 1597:, near the town of Meileyingzi, 1316:for the specimen BPV.149 in the 1297:were both known form Oshih; and 973:. Osborn created the new family 588: 144: 7341:Lucas, Spencer G. (2006). "The 6745:(1) (English ed.): 15–20. 6511:Journal of Experimental Zoology 6426:"This Dinosaur Wore Camouflage" 4584:PhD Thesis, Columbia University 4524:Natural History of Central Asia 4166:animals, a similar injury to a 2169:). The smallest known species, 2101:of Mongolia. It is named after 1490:was found in the Aptian-Albian 1095:. An additional tooth, partial 761:. The first species was either 674:, existing between 125 and 105 27:Early Cretaceous dinosaur genus 5296:Psittacosaurus mazongshanensis 5072:10.1080/02724634.1988.10011725 5028:10.1080/02724634.1988.10011724 4622:Palaeontologia Sinica Series C 4322:The earliest known species is 2587:bones, a feature also seen in 1984:, and potentially the same as 1: 8929:Early Cretaceous ceratopsians 8909:Fossil taxa described in 1923 7367:10.1016/j.cretres.2005.11.011 7321:Acta Palaeontologica Polonica 7237:10.1016/j.cretres.2014.06.015 7163:Acta Palaeontologica Polonica 6037:The Encyclopedia of Dinosaurs 5889:10.1016/j.cretres.2006.08.005 5704:Acta Palaeontologica Polonica 5556:10.1016/j.cretres.2006.05.011 5476:Acta Palaeontologica Polonica 5048:Psittacosaurus meileyingensis 4933:The Encyclopedia of Dinosaurs 4838:Acta Palaeontologica Polonica 4149:, but very clear signs of an 4133:Out of the hundreds of known 3909:in its stomach region (arrow) 739:, it is now considered to be 7017:Psittacosaurus lujiatunensis 6905:10.1016/j.palwor.2007.07.002 6856:10.1371/journal.pone.0112055 5609:10.1371/journal.pone.0069265 5348:10.1016/j.palwor.2005.11.001 5004:Psittacosaurus xinjiangensis 4973:Psittacosaurus xinjiangensis 3441:and colleagues in 2008, and 2690:, and to a lesser degree in 1584:Copenhagen Zoological Museum 511:Sereno, Zhao & Tan, 2010 6708:Psittacosaurus mongoliensis 6573:"Structure and homology of 6241:Lingham-Soliar, T. (2008). 6073:Psittacosaurus mongoliensis 6041:. Academic Press. pp. 4810:Cheng, Zhengwu (1983). "". 4024:hatchling conserved in the 2678:has the shortest snout and 2145:. Several species approach 1656:were described by Canadian 1338:Psittacosaurus mongoliensis 1251:Psittacosaurus mongoliensis 1249:, as otherwise both it and 1184:Psittacosaurus mongoliensis 1136:Psittacosaurus mongoliensis 1130:uncovered more material of 1032:by American paleontologist 911:Psittacosaurus mongoliensis 312:Psittacosaurus mongoliensis 8945: 7384:Chinese Fossil Vertebrates 7380:Lucas, Spencer G. (2001). 6683:Osborn, Henry F. (1924). " 6651:10.1186/s12915-022-01329-9 4084:The find of a herd of six 2746:was probably smaller than 2271: 2268:Soft tissue and coloration 1928:: "hill"), as well as the 1912:in 2003. The generic name 1904:, Hong Kong Science Museum 1558:Xinjiang Autonomous Region 1409:Psittacosaurus guyangensis 1340:fossils are found in most 1237:to be a junior synonym of 1146:. Soviet excavations near 854:, American paleontologist 8692: 8670: 8432: 8222: 8163: 8148: 8135: 8113: 8041: 7862: 7732: 7728: 7636: 7632: 7617: 7604: 7550: 7523: 7510: 7455: 6693:American Museum Novitates 6477:10.1016/j.cub.2016.06.065 6368:10.1016/j.cub.2016.06.065 6320:10.1016/j.cub.2020.12.039 6192:10.1007/s00114-002-0339-6 5993:American Museum Novitates 5928:10.1007/s00114-002-0339-6 5218:10.1017/s1477201906001933 4461:American Museum Novitates 4425:American Museum Novitates 4291:fossils is from the late 3823:can be inferred from the 3773:encephalization quotients 3668: 3651: 3644: 3627: 3620: 3603: 3596: 3579: 3572: 3546: 3529: 3522: 3515: 3489: 3472: 3465: 3458: 3425:Although many species of 3304: 3289: 3282: 3265: 3258: 3232: 3215: 3208: 3201: 3175: 3158: 3151: 3144: 3127: 3120: 3103: 3096: 3067: 3050: 3043: 3031: 3005: 2988: 2981: 2974: 2957: 2950: 2930: 2920: 2432:Model based on SMF R 4970 2425:, based on hip features. 1737:Lower Xinminbao Formation 1514:. Chinese paleontologist 1506:to differentiate it from 1243:Protiguanodon mongoliense 1168:Protiguanodon mongoliense 1166:, who also proposed that 1140:Paleontological Institute 927:Protiguanodon mongoliense 544: 537: 327: 322: 306: 299: 141:Scientific classification 139: 128: 119: 34: 18:Species of Psittacosaurus 8884:Paleontology in Shandong 5467:Psittacosaurus sibiricus 5194:Psittacosaurus sibiricus 4661:Zhao, Xijin (1962). "". 4208:animal. One skeleton of 3905:specimen AMNH 6254 with 3437:and colleagues in 2006, 2605:. The skull of an adult 2436:Another 2016 study used 2204:Skeletal restoration of 2014:to be synonymous. While 1948:and only named species, 1502:. C. C. Young called it 1193:Holotype (IVPP V738) of 440:Russell & Zhao, 1996 7649:Micropachycephalosaurus 6940:10.1126/science.1200043 5987:Psittacosaurus amitabha 5514:Acta Petrologica Sinica 4258:Shanghai Ocean Aquarium 4056:study performed on the 2497:Species characteristics 2316:, or body covering, of 1218:Psittacosaurus sinensis 1093:Xinpongnaobao Formation 6798:10.1098/rspb.2006.3566 6259:10.1098/rspb.2007.1342 5762:10.1098/rspb.2009.0691 5488:10.4202/app.00819.2020 5390:10.1006/cres.2000.0242 4663:Vertebrata PalAsiatica 4451:Osborn, H.F. (1924). " 4330:put the Yixian in the 4261: 4197: 4105: 4081: 4013: 3939: 3918:, as in modern birds. 3910: 3816: 3760: 3422: 2872:, was lost during the 2826: 2815: 2506: 2433: 2209: 2173:, is 30% smaller than 2122: 1905: 1615:and a Thai colleague, 1611:French paleontologist 1586: 1435: 1312:, giving the new name 1197: 1172:Psittacosaurus osborni 1160:Anatoly Rozhdestvensky 1069:Psittacosaurus osborni 1052: 856:Henry Fairfield Osborn 847: 828: 824:(specimen AMNH 6254), 8889:Paleontology in Gansu 8824:Paleobiology Database 7172:10.4202/app.2012.0128 7023:Nature Communications 6739:Acta Geologica Sinica 6554:"Feathers or scales?" 5717:10.4202/app.2008.0202 5697:Psittacosaurus major" 5647:Acta Geologica Sinica 5450:10.1144/SP545-2023-62 4641:Voprosy Geologii Asii 4249: 4234:may have resulted in 4185: 4103: 4079: 4008:Skull of a hatchling 4007: 3933: 3901: 3811: 3755: 3413: 2821: 2813: 2504: 2431: 2403:disruptive coloration 2203: 2116: 2070:Museum of the Rockies 1916:was derived from the 1899: 1578: 1430: 1314:Psittacosaurus youngi 1295:P. protiguanodonensis 1245:the new species name 1192: 1043: 834: 816: 331:List of other species 8919:Ornithischian genera 8854:Ceratopsians of Asia 7414:at Wikimedia Commons 6432:on 15 September 2016 6230:doi:10.1038/35102731 5643:Hongshanosaurus houi 4307:). Many terrestrial 4211:Repenomamus robustus 4189:Repenomamus robustus 4072:Gregarious juveniles 2802:was a contemporary. 2457:and the "beards" of 2262:convergent evolution 2099:Andakhuduk Formation 2093:was named by Napoli 1972:skulls. He regarded 1910:Hongshanosaurus houi 1863:Psittacosaurus major 1825:Hongshanosaurus houi 1621:Khok Kruat Formation 1269:a junior synonym of 1176:Psittacosaurus tingi 931:Ondai Sair Formation 915:William King Gregory 809:History of discovery 8904:Fossils of Thailand 8899:Cretaceous Thailand 8874:Fossils of Mongolia 8869:Cretaceous Mongolia 8859:Feathered dinosaurs 7814:Archaeoceratopsidae 7359:2006CrRes..27..189L 7347:Cretaceous Research 7279:10.1038/nature03102 7271:2005Natur.433..149H 7229:2014CrRes..51..321H 7217:Cretaceous Research 7091:2007Palgy..50.1023Q 7035:2013NatCo...4.2079Z 6932:2011Sci...332..705S 6847:2014PLoSO...9k2055F 6792:(1598): 2135–2140. 6751:2003AcGlS..77...15Y 6593:2016Palgy..59..793M 6523:2003JEZ...297...27S 6469:2016CBio...26.2456V 6360:2016CBio...26.2456V 6311:2021CBio...31.R182V 6184:2002NW.....89..361M 6172:Naturwissenschaften 6141:doi:10.1038/414571a 5920:2002NW.....89..361M 5908:Naturwissenschaften 5881:2007CrRes..28..272L 5869:Cretaceous Research 5819:2004Natur.431..145M 5659:2005AcGlS..79..168Y 5600:2013PLoSO...869265H 5548:2007CrRes..28..177Y 5536:Cretaceous Research 5442:2023GSLSP.545...62I 5382:2001CrRes..22..115T 5370:Cretaceous Research 5270:1996CaJES..33..637R 5210:2006JSPal...4..359A 5107:1993CaJES..30.2101E 5064:1988JVPal...8..366S 5020:1988JVPal...8..353S 4376:Dinosaur coloration 4348:uranium–lead dating 4285:geologic formations 4250:Specimen alongside 3852:semicircular canals 3783:. The EQ score for 3435:Alexander Averianov 2865:antorbital fenestra 2825:skull in front view 2274:Feathered dinosaurs 2117:Size comparison of 2062:Bolortsetseg Minjin 2054:feathered dinosaurs 1791:Alexander Averianov 1676:in 1996, after the 1652:Two new species of 1617:Varavudh Suteethorn 1595:Jiufotang Formation 1034:Roy Chapman Andrews 8534:Crittendenceratops 8484:Albertaceratopsini 7044:10.1038/ncomms3079 6601:10.1111/pala.12257 6558:Journal of Geology 6552:Qiang, Ji (2016). 6107:Journal of Zoology 4340:argon–argon dating 4328:radiometric dating 4262: 4198: 4106: 4082: 4014: 3944:P. neimongoliensis 3940: 3911: 3817: 3761: 3607:P. neimongoliensis 3550:P. mazongshanensis 3423: 2927:Pachycephalosauria 2827: 2816: 2758:The type skull of 2744:P. neimongoliensis 2732:P. neimongoliensis 2559:bone contacts the 2507: 2434: 2330:Senckenberg Museum 2210: 2177:. The largest are 2155:P. neimongoliensis 2123: 1906: 1787:Alexei Voronkevich 1745:P. mazongshanensis 1729:P. mazongshanensis 1706:P. mazongshanensis 1683:P. neimongoliensis 1670:Ejinhoro Formation 1662:P. neimongoliensis 1642:P. neimongoliensis 1587: 1556:, named after the 1492:Qingshan Formation 1436: 1214:Qingshan Formation 1198: 1053: 995:Protiguanodontinae 989:within the family 985:, while he placed 892:Khukhtek Formation 848: 829: 449:P. mazongshanensis 418:P. neimongoliensis 8839: 8838: 8811:Open Tree of Life 8725:Taxon identifiers 8716: 8715: 8688: 8687: 8668: 8667: 8664: 8663: 8660: 8659: 8656: 8655: 8617:Pachyrhinosaurini 8555:Yehuecauhceratops 8518:Nasutoceratopsini 8419: 8418: 8131: 8130: 8111: 8110: 8107: 8106: 8103: 8102: 8099: 8098: 8095: 8094: 8091: 8090: 7992:Protoceratopsidae 7879:Leptoceratopsidae 7847: 7846: 7713: 7712: 7600: 7599: 7596: 7595: 7592: 7591: 7588: 7587: 7410:Media related to 7265:(7022): 149–152. 7150:Zhao, Q. (2013). 6984:978-0-253-35358-0 6463:(18): 2456–2462. 6354:(18): 2456–2462. 6253:(1636): 775–780. 5813:(7005): 145–146. 5756:(1679): 199–209. 5101:(10): 2101–2106. 4983:(12): 1781–1786. 4305:million years ago 4161:due to a lack of 4054:age determination 4016:Several juvenile 3737: 3736: 3728: 3727: 3719: 3718: 3710: 3709: 3701: 3700: 3692: 3691: 3683: 3682: 3655:P. meileyingensis 3561: 3560: 3504: 3503: 3407: 3406: 3398: 3397: 3389: 3388: 3380: 3379: 3371: 3370: 3362: 3361: 3353: 3352: 3344: 3343: 3335: 3334: 3326: 3325: 3317: 3316: 3292:Leptoceratopsidae 3247: 3246: 3190: 3189: 3082: 3081: 3020: 3019: 2897:Leptoceratopsidae 2720:P. meileyingensis 2676:P. meileyingensis 2649:P. meileyingensis 2527:P. meileyingensis 2385:tissue fibres in 2355:ultraviolet light 2326:Liaoning Province 2167:P. meileyingensis 1839:, opted to leave 1599:Liaoning Province 1591:P. meileyingensis 1580:P. meileyingensis 1570:P. meileyingensis 1496:Shandong Province 1360:Cretaceous Period 1261:as separate from 1051:from Osborn, 1923 783:growth rates and 698:. The species of 676:million years ago 579: 578: 573: 553: 530: 512: 498: 478: 458: 441: 427: 410: 388: 370: 358:P. meileyingensis 350: 295: 276: 130:P. meileyingensis 16:(Redirected from 8936: 8879:Cretaceous China 8832: 8831: 8819: 8818: 8806: 8805: 8793: 8792: 8780: 8779: 8767: 8766: 8765: 8752: 8751: 8750: 8720: 8706: 8705: 8683: 8682: 8676: 8647:Pachyrhinosaurus 8571: 8445:Machairoceratops 8430: 8270:Coahuilaceratops 8220: 8161: 8150: 8137: 8126: 8121: 8120: 8039: 7988: 7972:Zhuchengceratops 7860: 7730: 7726: 7667:Chaoyangsauridae 7634: 7630: 7619: 7606: 7548: 7521: 7512: 7505: 7504: 7457: 7442: 7435: 7428: 7419: 7409: 7394: 7393: 7387: 7377: 7371: 7370: 7338: 7329: 7328: 7318: 7305: 7299: 7298: 7256: 7247: 7241: 7240: 7208: 7202: 7201: 7199: 7197: 7183: 7177: 7176: 7174: 7160: 7147: 7138: 7137: 7117: 7111: 7110: 7085:(5): 1023–1029. 7076: 7063: 7057: 7056: 7046: 7010: 7004: 7003: 6995: 6989: 6988: 6966: 6960: 6959: 6915: 6909: 6908: 6888: 6879: 6878: 6868: 6858: 6826: 6820: 6819: 6809: 6777: 6771: 6770: 6734: 6728: 6727: 6703: 6697: 6696: 6680: 6674: 6673: 6663: 6653: 6629: 6623: 6622: 6612: 6568: 6562: 6561: 6549: 6543: 6542: 6531:10.1002/jez.b.17 6505: 6499: 6498: 6488: 6448: 6442: 6441: 6439: 6437: 6422: 6416: 6415: 6413: 6411: 6396: 6390: 6389: 6379: 6339: 6333: 6332: 6322: 6305:(4): R182–R183. 6290: 6281: 6280: 6270: 6238: 6232: 6218: 6212: 6211: 6169: 6156: 6143: 6129: 6123: 6122: 6102: 6093: 6092: 6068: 6057: 6056: 6040: 6030: 6021: 6020: 5980: 5974: 5973: 5971: 5969: 5957: 5948: 5947: 5899: 5893: 5892: 5860: 5847: 5846: 5804: 5795: 5784: 5783: 5773: 5741: 5730: 5729: 5719: 5701: 5688: 5679: 5678: 5638: 5632: 5631: 5621: 5611: 5579: 5568: 5567: 5531: 5522: 5521: 5509: 5500: 5499: 5473: 5460: 5454: 5453: 5424: 5418: 5417: 5408: 5402: 5401: 5367: 5358: 5352: 5351: 5325: 5304: 5303: 5291: 5282: 5281: 5253: 5230: 5229: 5189: 5168: 5167: 5151: 5145: 5144: 5128: 5119: 5118: 5090: 5084: 5083: 5043: 5032: 5031: 4999: 4993: 4992: 4968: 4953: 4952: 4936: 4926: 4920: 4919: 4903: 4892: 4881: 4880: 4872: 4853: 4852: 4851: 4845: 4835: 4826: 4815: 4814: 4807: 4801: 4800: 4784: 4770: 4755: 4754: 4738: 4727: 4726: 4710: 4700: 4671: 4670: 4658: 4649: 4648: 4636: 4630: 4629: 4617: 4604: 4594: 4588: 4587: 4575: 4564: 4563: 4543: 4532: 4531: 4519: 4513: 4512: 4500: 4465: 4464: 4448: 4439: 4438: 4436: 4420: 4407: 4406: 4396: 4370: 4368:Dinosaurs portal 4365: 4364: 4363: 4324:P. lujiatunensis 4277:Early Cretaceous 3785:P. lujiatunensis 3765:P. lujiatunensis 3757:P. lujiatunensis 3742:P. lujiatunensis 3647: 3623: 3599: 3575: 3533:P. lujiatunensis 3525: 3518: 3468: 3461: 3449: 3285: 3261: 3211: 3204: 3154: 3147: 3123: 3099: 3046: 3034: 2984: 2977: 2953: 2923: 2913: 2848:Chaoyangsauridae 2846:and perhaps the 2760:P. lujiatunensis 2716:P. lujiatunensis 2688:P. lujiatunensis 2664:P. xinjiangensis 2577:P. lujiatunensis 2535:P. lujiatunensis 2515:antorbital fossa 2479:P. lujiatunensis 2322:Yixian Formation 2302: 2286: 2179:P. lujiatunensis 2159:P. xinjiangensis 2151:P. lujiatunensis 2141:(44 lb) in 2076:. Although only 2024:P. lujiatunensis 2020:P. lujiatunensis 2012:P. lujiatunensis 1986:P. lujiatunensis 1938:Hongshan culture 1924:: "red") and 山 ( 1918:Mandarin Chinese 1879:P. lujiatunensis 1867:P. lujiatunensis 1859:P. lujiatunensis 1841:P. lujiatunensis 1835:is a synonym of 1821:P. lujiatunensis 1817:Yixian Formation 1809:P. lujiatunensis 1803:P. lujiatunensis 1666:Mandarin Chinese 1554:P. xinjiangensis 1543:P. xinjiangensis 1423:Assigned species 1373:as a synonym of 975:Psittacosauridae 896:Early Cretaceous 838:AMNH 6253, the " 763:P. lujiatunensis 641: 637: 632: 631: 628: 627: 624: 621: 618: 615: 612: 609: 606: 603: 600: 597: 594: 560: 551: 524: 517: 510: 503: 490: 486:P. lujiatunensis 483: 470: 463: 453: 446: 439: 432: 426:& Zhao, 1996 422: 415: 401: 393: 382: 378:P. xinjiangensis 375: 362: 355: 345: 338: 309: 293: 286: 271: 268:Psittacosauridae 266: 253: 237: 221: 205: 149: 148: 124: 114: 51: 42:Early Cretaceous 40:Temporal range: 32: 21: 8944: 8943: 8939: 8938: 8937: 8935: 8934: 8933: 8844: 8843: 8840: 8835: 8827: 8822: 8814: 8809: 8801: 8796: 8788: 8783: 8775: 8770: 8761: 8760: 8755: 8746: 8745: 8740: 8727: 8717: 8712: 8684: 8677: 8652: 8611: 8560: 8541:Furcatoceratops 8512: 8493:Albertaceratops 8478: 8452:Menefeeceratops 8415: 8388:Tatankaceratops 8345: 8291:Mercuriceratops 8242:Arrhinoceratops 8209: 8157: 8144: 8127: 8115: 8087: 8067: 8028: 7977: 7944:Montanoceratops 7873: 7868:Graciliceratops 7856: 7843: 7823:Archaeoceratops 7808: 7722: 7709: 7697:Xuanhuaceratops 7683:Hualianceratops 7661: 7642:Albalophosaurus 7626: 7613: 7584: 7564: 7537: 7531:Avemetatarsalia 7516:Avemetatarsalia 7506: 7500:Marginocephalia 7462: 7461: 7451: 7446: 7402: 7397: 7379: 7378: 7374: 7340: 7339: 7332: 7316: 7307: 7306: 7302: 7254: 7249: 7248: 7244: 7210: 7209: 7205: 7195: 7193: 7185: 7184: 7180: 7158: 7149: 7148: 7141: 7119: 7118: 7114: 7074: 7065: 7064: 7060: 7012: 7011: 7007: 7002:. ScienceDaily. 6997: 6996: 6992: 6985: 6968: 6967: 6963: 6926:(6030): 705–8. 6917: 6916: 6912: 6890: 6889: 6882: 6841:(12): e112055. 6828: 6827: 6823: 6779: 6778: 6774: 6736: 6735: 6731: 6705: 6704: 6700: 6682: 6681: 6677: 6631: 6630: 6626: 6570: 6569: 6565: 6551: 6550: 6546: 6507: 6506: 6502: 6457:Current Biology 6450: 6449: 6445: 6435: 6433: 6424: 6423: 6419: 6409: 6407: 6398: 6397: 6393: 6348:Current Biology 6341: 6340: 6336: 6299:Current Biology 6292: 6291: 6284: 6240: 6239: 6235: 6219: 6215: 6167: 6158: 6157: 6146: 6130: 6126: 6104: 6103: 6096: 6070: 6069: 6060: 6053: 6032: 6031: 6024: 5982: 5981: 5977: 5967: 5965: 5959: 5958: 5951: 5901: 5900: 5896: 5862: 5861: 5850: 5827:10.1038/431145a 5802: 5797: 5796: 5787: 5743: 5742: 5733: 5699: 5690: 5689: 5682: 5640: 5639: 5635: 5581: 5580: 5571: 5533: 5532: 5525: 5511: 5510: 5503: 5471: 5462: 5461: 5457: 5426: 5425: 5421: 5410: 5409: 5405: 5365: 5360: 5359: 5355: 5327: 5326: 5307: 5293: 5292: 5285: 5278:10.1139/e96-047 5255: 5254: 5233: 5191: 5190: 5171: 5153: 5152: 5148: 5130: 5129: 5122: 5115:10.1139/e93-182 5092: 5091: 5087: 5045: 5044: 5035: 5001: 5000: 4996: 4989:10.1139/e01-049 4970: 4969: 4956: 4949: 4928: 4927: 4923: 4916: 4894: 4893: 4884: 4874: 4873: 4856: 4846: 4833: 4828: 4827: 4818: 4809: 4808: 4804: 4797: 4772: 4771: 4758: 4740: 4739: 4730: 4723: 4702: 4701: 4674: 4660: 4659: 4652: 4638: 4637: 4633: 4619: 4618: 4607: 4595: 4591: 4577: 4576: 4567: 4545: 4544: 4535: 4521: 4520: 4516: 4502: 4501: 4468: 4450: 4449: 4442: 4422: 4421: 4410: 4398: 4397: 4393: 4389: 4366: 4361: 4359: 4356: 4332:Jurassic Period 4269:P. mongoliensis 4244: 4242:Paleochronology 4180: 4143:P. mongoliensis 4131: 4119:P. mongoliensis 4074: 4062:P. mongoliensis 4037:P. mongoliensis 4035:examination of 4022:P. mongoliensis 4010:P. mongoliensis 4002: 3948:P. mongoliensis 3936:P. mongoliensis 3928: 3903:P. mongoliensis 3896: 3834:sclerotic rings 3829:olfactory bulbs 3814:P. mongoliensis 3812:Restoration of 3750: 3738: 3729: 3720: 3711: 3702: 3693: 3684: 3672:P. mongoliensis 3562: 3505: 3416:P. mongoliensis 3408: 3399: 3390: 3381: 3372: 3363: 3354: 3345: 3336: 3327: 3318: 3248: 3236:Archaeoceratops 3191: 3083: 3071:P. mongoliensis 3021: 2992:Xuanhuaceratops 2917:Marginocephalia 2884:a second time. 2808: 2800:P. mongoliensis 2772:P. mongoliensis 2764:P. mongoliensis 2748:P. mongoliensis 2708:P. mongoliensis 2692:P. mongoliensis 2645:P. mongoliensis 2571:species except 2553:P. mongoliensis 2539:P. mongoliensis 2511:P. mongoliensis 2499: 2474:Psittacosaurus' 2455:horned screamer 2423:P. mongoliensis 2416:Jehol Formation 2310: 2309: 2308: 2307: 2306: 2303: 2295: 2294: 2287: 2276: 2270: 2187:P. mongoliensis 2175:P. mongoliensis 2147:P. mongoliensis 2143:P. mongoliensis 2135:P. mongoliensis 2125:The species of 2119:P. mongoliensis 2111: 2103:Amitabha Buddha 2078:P. mongoliensis 1974:Hongshanosaurus 1970:Hongshanosaurus 1964:, Xu Xing, and 1944:was found. The 1942:Hongshanosaurus 1914:Hongshanosaurus 1902:Hongshanosaurus 1875:P. mongoliensis 1833:Hongshanosaurus 1779:Western Siberia 1775:Kemerovo Oblast 1512:P. mongoliensis 1508:P. mongoliensis 1498:, southeast of 1431:Restoration of 1425: 1413:P. mongoliensis 1391:P. mongoliensis 1375:P. mongoliensis 1299:P. mongoliensis 1291:P. mongoliensis 1287:P. mongoliensis 1263:P. mongoliensis 1180:junior synonyms 1117:P. mongoliensis 1049:P. mongoliensis 876:Oshih Formation 836:P. mongoliensis 822:P. mongoliensis 811: 737:Hongshanosaurus 670:of what is now 666:from the Early 639: 635: 591: 587: 559: 557:Hongshanosaurus 550: 533: 523: 509: 489: 469: 452: 438: 421: 400: 381: 361: 344: 333: 332: 318: 315: 292: 284: 270: 264: 251: 239:Marginocephalia 235: 219: 203: 143: 115: 113: 112: 107: 102: 97: 92: 87: 82: 77: 72: 67: 62: 57: 46: 45: 38: 28: 23: 22: 15: 12: 11: 5: 8942: 8940: 8932: 8931: 8926: 8921: 8916: 8911: 8906: 8901: 8896: 8891: 8886: 8881: 8876: 8871: 8866: 8861: 8856: 8846: 8845: 8837: 8836: 8834: 8833: 8820: 8807: 8794: 8781: 8768: 8763:Psittacosaurus 8753: 8737: 8735: 8733:Psittacosaurus 8729: 8728: 8723: 8714: 8713: 8711: 8710: 8700: 8693: 8690: 8689: 8686: 8685: 8671: 8669: 8666: 8665: 8662: 8661: 8658: 8657: 8654: 8653: 8651: 8650: 8643: 8636: 8629: 8621: 8619: 8613: 8612: 8610: 8609: 8601: 8594: 8587: 8579: 8577: 8568: 8562: 8561: 8559: 8558: 8551: 8548:Nasutoceratops 8544: 8537: 8530: 8522: 8520: 8514: 8513: 8511: 8510: 8507:Medusaceratops 8503: 8496: 8488: 8486: 8480: 8479: 8477: 8476: 8469: 8462: 8455: 8448: 8441: 8438:Diabloceratops 8433: 8427: 8425:Centrosaurinae 8421: 8420: 8417: 8416: 8414: 8413: 8406: 8399: 8396:Titanoceratops 8392: 8384: 8381:Regaliceratops 8377: 8370: 8363: 8355: 8353: 8351:Triceratopsini 8347: 8346: 8344: 8343: 8336: 8329: 8322: 8315: 8312:Sierraceratops 8308: 8301: 8298:Navajoceratops 8294: 8287: 8280: 8273: 8266: 8259: 8252: 8245: 8238: 8231: 8223: 8217: 8215:Chasmosaurinae 8211: 8210: 8208: 8207: 8200: 8193: 8186: 8179: 8176:Brachyceratops 8172: 8164: 8158: 8153: 8146: 8145: 8140: 8133: 8132: 8129: 8128: 8114: 8112: 8109: 8108: 8105: 8104: 8101: 8100: 8097: 8096: 8093: 8092: 8089: 8088: 8086: 8085: 8084: 8083: 8077: 8075: 8069: 8068: 8066: 8065: 8058: 8055:Turanoceratops 8051: 8042: 8036: 8030: 8029: 8027: 8026: 8019: 8012: 8005: 7996: 7994: 7985: 7979: 7978: 7976: 7975: 7968: 7965:Unescoceratops 7961: 7954: 7947: 7940: 7933: 7930:Ischioceratops 7926: 7923:Gryphoceratops 7919: 7912: 7905: 7898: 7891: 7883: 7881: 7875: 7874: 7872: 7871: 7863: 7857: 7852: 7849: 7848: 7845: 7844: 7842: 7841: 7833: 7826: 7818: 7816: 7810: 7809: 7807: 7806: 7803:Sasayamagnomus 7799: 7792: 7785: 7778: 7770: 7763: 7756: 7753:Auroraceratops 7749: 7742: 7733: 7723: 7718: 7715: 7714: 7711: 7710: 7708: 7707: 7700: 7693: 7686: 7679: 7676:Chaoyangsaurus 7671: 7669: 7663: 7662: 7660: 7659: 7656:Psittacosaurus 7652: 7645: 7637: 7627: 7622: 7615: 7614: 7609: 7602: 7601: 7598: 7597: 7594: 7593: 7590: 7589: 7586: 7585: 7583: 7582: 7581: 7580: 7574: 7572: 7566: 7565: 7563: 7562: 7561: 7560: 7551: 7545: 7539: 7538: 7536: 7535: 7534: 7533: 7524: 7518: 7508: 7507: 7503: 7502: 7493: 7484: 7475: 7469: 7460: 7453: 7452: 7447: 7445: 7444: 7437: 7430: 7422: 7416: 7415: 7412:Psittacosaurus 7401: 7400:External links 7398: 7396: 7395: 7372: 7353:(2): 189–198. 7343:Psittacosaurus 7330: 7312:Psittacosaurus 7300: 7242: 7213:Psittacosaurus 7203: 7178: 7154:Psittacosaurus 7139: 7112: 7070:Psittacosaurus 7058: 7005: 6990: 6983: 6971:Psittacosaurus 6961: 6910: 6899:(4): 285–293. 6880: 6821: 6772: 6729: 6718:(4): 551–566. 6698: 6685:Psittacosaurus 6675: 6624: 6587:(6): 793–802. 6577:tail bristles" 6575:Psittacosaurus 6563: 6544: 6500: 6443: 6417: 6391: 6334: 6282: 6233: 6213: 6178:(8): 361–365. 6163:Psittacosaurus 6144: 6124: 6113:(3): 305–314. 6094: 6083:(4): 551–566. 6058: 6051: 6022: 6001:10.1206/3932.1 5995:(3932): 1–36. 5975: 5949: 5914:(8): 361–365. 5904:Psittacosaurus 5894: 5875:(2): 272–276. 5865:Psittacosaurus 5848: 5785: 5731: 5710:(2): 183–196. 5680: 5633: 5569: 5542:(2): 177–182. 5523: 5501: 5482:(2): 437–447. 5455: 5419: 5403: 5376:(1): 115–129. 5353: 5330:Psittacosaurus 5305: 5283: 5264:(4): 637–648. 5231: 5204:(4): 359–395. 5169: 5156:P. sattayaraki 5146: 5133:Psittacosaurus 5120: 5085: 5058:(4): 366–377. 5033: 5014:(4): 353–365. 4994: 4954: 4947: 4921: 4914: 4882: 4854: 4816: 4802: 4795: 4775:Psittacosaurus 4756: 4743:Psittacosaurus 4728: 4721: 4707:The Dinosauria 4672: 4665:(in Chinese). 4650: 4631: 4605: 4589: 4580:Psittacosaurus 4565: 4554:(3): 259–266. 4533: 4514: 4505:Psittacosaurus 4466: 4453:Psittacosaurus 4440: 4408: 4390: 4388: 4385: 4384: 4383: 4378: 4372: 4371: 4355: 4352: 4336:Psittacosaurus 4317:Psittacosaurus 4313:Psittacosaurus 4289:Psittacosaurus 4273:Psittacosaurus 4265:Psittacosaurus 4243: 4240: 4232:Psittacosaurus 4220:Psittacosaurus 4202:Psittacosaurus 4194:Psittacosaurus 4179: 4176: 4168:weight bearing 4135:Psittacosaurus 4130: 4127: 4110:Psittacosaurus 4091:gregariousness 4086:Psittacosaurus 4073: 4070: 4018:Psittacosaurus 4001: 3998: 3993:Psittacosaurus 3984:Psittacosaurus 3980:Psittacosaurus 3976:Psittacosaurus 3969:Psittacosaurus 3964:Psittacosaurus 3960:Psittacosaurus 3952:Psittacosaurus 3927: 3924: 3895: 3892: 3888:Psittacosaurus 3875:Psittacosaurus 3864:Psittacosaurus 3856:Psittacosaurus 3848:Psittacosaurus 3838:Psittacosaurus 3821:Psittacosaurus 3819:The senses of 3803:Psittacosaurus 3793:Psittacosaurus 3781:Psittacosaurus 3769:Psittacosaurus 3749: 3746: 3735: 3734: 3731: 3730: 3726: 3725: 3722: 3721: 3717: 3716: 3713: 3712: 3708: 3707: 3704: 3703: 3699: 3698: 3695: 3694: 3690: 3689: 3686: 3685: 3681: 3680: 3677: 3676: 3667: 3664: 3663: 3660: 3659: 3650: 3645: 3643: 3640: 3639: 3636: 3635: 3626: 3621: 3619: 3616: 3615: 3612: 3611: 3602: 3597: 3595: 3592: 3591: 3588: 3587: 3578: 3573: 3571: 3568: 3567: 3564: 3563: 3559: 3558: 3555: 3554: 3545: 3542: 3541: 3538: 3537: 3528: 3523: 3521: 3516: 3514: 3511: 3510: 3507: 3506: 3502: 3501: 3498: 3497: 3488: 3485: 3484: 3481: 3480: 3471: 3466: 3464: 3459: 3457: 3454:Psittacosaurus 3447: 3427:Psittacosaurus 3405: 3404: 3401: 3400: 3396: 3395: 3392: 3391: 3387: 3386: 3383: 3382: 3378: 3377: 3374: 3373: 3369: 3368: 3365: 3364: 3360: 3359: 3356: 3355: 3351: 3350: 3347: 3346: 3342: 3341: 3338: 3337: 3333: 3332: 3329: 3328: 3324: 3323: 3320: 3319: 3315: 3314: 3311: 3310: 3303: 3300: 3299: 3296: 3295: 3288: 3283: 3281: 3278: 3277: 3274: 3273: 3264: 3259: 3257: 3254: 3253: 3250: 3249: 3245: 3244: 3241: 3240: 3231: 3228: 3227: 3224: 3223: 3214: 3209: 3207: 3202: 3200: 3197: 3196: 3193: 3192: 3188: 3187: 3184: 3183: 3174: 3171: 3170: 3167: 3166: 3162:Auroraceratops 3157: 3152: 3150: 3145: 3143: 3140: 3139: 3136: 3135: 3126: 3121: 3119: 3116: 3115: 3112: 3111: 3102: 3097: 3095: 3089: 3088: 3085: 3084: 3080: 3079: 3076: 3075: 3066: 3063: 3062: 3059: 3058: 3049: 3044: 3042: 3039:Psittacosaurus 3032: 3030: 3027: 3026: 3023: 3022: 3018: 3017: 3014: 3013: 3009:Chaoyangsaurus 3004: 3001: 3000: 2997: 2996: 2987: 2982: 2980: 2975: 2973: 2970: 2969: 2966: 2965: 2956: 2951: 2949: 2943: 2942: 2939: 2938: 2929: 2921: 2919: 2911: 2889:Psittacosaurus 2860:Psittacosaurus 2852:Psittacosaurus 2830:Psittacosaurus 2807: 2806:Classification 2804: 2792:Psittacosaurus 2784:Psittacosaurus 2704:P. sattayaraki 2696:P. sattayaraki 2657:Psittacosaurus 2653:P. sattayaraki 2617:Psittacosaurus 2569:Psittacosaurus 2498: 2495: 2491:Psittacosaurus 2419:Psittacosaurus 2395:Psittacosaurus 2387:Psittacosaurus 2378:Psittacosaurus 2318:Psittacosaurus 2304: 2297: 2296: 2288: 2281: 2280: 2279: 2278: 2277: 2269: 2266: 2246:Psittacosaurus 2214:Psittacosaurus 2208:sp. SMF R 4970 2206:Psittacosaurus 2191:Psittacosaurus 2127:Psittacosaurus 2110: 2107: 2088: 2087: 2058:Psittacosaurus 2050:Psittacosaurus 2046:Psittacosaurus 2038: 2037: 2004:Psittacosaurus 1982:Psittacosaurus 1978:junior synonym 1894: 1893: 1855: 1854: 1837:Psittacosaurus 1806: 1805: 1795:Ilek Formation 1771:Psittacosaurus 1767: 1766: 1757:Psittacosaurus 1753:Psittacosaurus 1725:Gansu Province 1717:Psittacosaurus 1710: 1709: 1654:Psittacosaurus 1650: 1649: 1634:incertae sedis 1629:Psittacosaurus 1625:P. sattayaraki 1613:Eric Buffetaut 1609: 1608: 1606:P. sattayaraki 1573: 1572: 1546: 1545: 1532:P. guyangensis 1488:Psittacosaurus 1484: 1483: 1470:Psittacosaurus 1452:Psittacosaurus 1448:Psittacosaurus 1440:Psittacosaurus 1424: 1421: 1417:P. guyangensis 1347:dating to the 1275:Psittacosaurus 1239:Psittacosaurus 1231:Psittacosaurus 1226:Psittacosaurus 1210:Psittacosaurus 1156:Psittacosaurus 1132:Psittacosaurus 1105:Psittacosaurus 1081:Psittacosaurus 1073:sagittal crest 1065:Yang Zhongjian 1061:Inner Mongolia 1026:Psittacosaurus 1014:Psittacosaurus 1006:Psittacosaurus 991:Iguanodontidae 979:Psittacosaurus 971:quadrate bones 967:parietal bones 963:Psittacosaurus 947:Psittacosaurus 923:Psittacosaurus 810: 807: 800:Psittacosaurus 781:Psittacosaurus 773:Psittacosaurus 767:Psittacosaurus 749:Psittacosaurus 741:senior synonym 721:Psittacosaurus 714:Psittacosaurus 702:were obligate 700:Psittacosaurus 583:Psittacosaurus 577: 576: 575: 574: 554: 542: 541: 535: 534: 532: 531: 513: 499: 479: 459: 442: 428: 411: 397:P. sattayaraki 389: 371: 351: 330: 329: 328: 325: 324: 323:Other species 320: 319: 316: 304: 303: 297: 296: 289:Psittacosaurus 282: 278: 277: 262: 258: 257: 249: 242: 241: 233: 226: 225: 223:Neornithischia 217: 210: 209: 201: 194: 193: 188: 181: 180: 175: 171: 170: 165: 161: 160: 155: 151: 150: 137: 136: 126: 125: 117: 116: 108: 103: 98: 93: 88: 83: 78: 73: 68: 63: 58: 53: 52: 39: 36:Psittacosaurus 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 8941: 8930: 8927: 8925: 8922: 8920: 8917: 8915: 8912: 8910: 8907: 8905: 8902: 8900: 8897: 8895: 8892: 8890: 8887: 8885: 8882: 8880: 8877: 8875: 8872: 8870: 8867: 8865: 8862: 8860: 8857: 8855: 8852: 8851: 8849: 8842: 8830: 8825: 8821: 8817: 8812: 8808: 8804: 8799: 8795: 8791: 8786: 8782: 8778: 8773: 8769: 8764: 8758: 8754: 8749: 8743: 8739: 8738: 8736: 8734: 8730: 8726: 8721: 8709: 8701: 8699: 8695: 8694: 8691: 8681: 8675: 8649: 8648: 8644: 8642: 8641: 8637: 8635: 8634: 8630: 8628: 8627: 8626:Achelousaurus 8623: 8622: 8620: 8618: 8614: 8607: 8606: 8605:Styracosaurus 8602: 8600: 8599: 8595: 8593: 8592: 8588: 8586: 8585: 8581: 8580: 8578: 8576: 8575:Centrosaurini 8572: 8569: 8567: 8566:Eucentrosaura 8563: 8557: 8556: 8552: 8550: 8549: 8545: 8543: 8542: 8538: 8536: 8535: 8531: 8529: 8528: 8524: 8523: 8521: 8519: 8515: 8509: 8508: 8504: 8502: 8501: 8497: 8495: 8494: 8490: 8489: 8487: 8485: 8481: 8475: 8474: 8470: 8468: 8467: 8466:Wendiceratops 8463: 8461: 8460: 8456: 8454: 8453: 8449: 8447: 8446: 8442: 8440: 8439: 8435: 8434: 8431: 8428: 8426: 8422: 8412: 8411: 8407: 8405: 8404: 8400: 8398: 8397: 8393: 8390: 8389: 8385: 8383: 8382: 8378: 8376: 8375: 8371: 8369: 8368: 8364: 8362: 8361: 8360:Eotriceratops 8357: 8356: 8354: 8352: 8348: 8342: 8341: 8337: 8335: 8334: 8330: 8328: 8327: 8323: 8321: 8320: 8316: 8314: 8313: 8309: 8307: 8306: 8305:Pentaceratops 8302: 8300: 8299: 8295: 8293: 8292: 8288: 8286: 8285: 8284:Kosmoceratops 8281: 8279: 8278: 8274: 8272: 8271: 8267: 8265: 8264: 8260: 8258: 8257: 8256:Bravoceratops 8253: 8251: 8250: 8249:Bisticeratops 8246: 8244: 8243: 8239: 8237: 8236: 8235:Anchiceratops 8232: 8230: 8229: 8228:Agujaceratops 8225: 8224: 8221: 8218: 8216: 8212: 8206: 8205: 8201: 8199: 8198: 8194: 8192: 8191: 8187: 8185: 8184: 8180: 8178: 8177: 8173: 8171: 8170: 8166: 8165: 8162: 8159: 8156: 8151: 8147: 8143: 8138: 8134: 8125: 8119: 8081: 8080: 8079: 8078: 8076: 8074: 8070: 8064: 8063: 8059: 8057: 8056: 8052: 8049: 8048: 8044: 8043: 8040: 8037: 8035: 8034:Ceratopsoidea 8031: 8025: 8024: 8023:Protoceratops 8020: 8018: 8017: 8016:Breviceratops 8013: 8011: 8010: 8006: 8003: 8002: 7998: 7997: 7995: 7993: 7989: 7986: 7984: 7980: 7974: 7973: 7969: 7967: 7966: 7962: 7960: 7959: 7958:Udanoceratops 7955: 7953: 7952: 7951:Prenoceratops 7948: 7946: 7945: 7941: 7939: 7938: 7937:Leptoceratops 7934: 7932: 7931: 7927: 7925: 7924: 7920: 7918: 7917: 7913: 7911: 7910: 7906: 7904: 7903: 7899: 7897: 7896: 7895:Bainoceratops 7892: 7890: 7889: 7885: 7884: 7882: 7880: 7876: 7870: 7869: 7865: 7864: 7861: 7858: 7855: 7850: 7839: 7838: 7834: 7832: 7831: 7830:Helioceratops 7827: 7825: 7824: 7820: 7819: 7817: 7815: 7811: 7805: 7804: 7800: 7798: 7797: 7796:Mosaiceratops 7793: 7791: 7790: 7786: 7784: 7783: 7779: 7776: 7775: 7771: 7769: 7768: 7767:Koreaceratops 7764: 7762: 7761: 7757: 7755: 7754: 7750: 7748: 7747: 7743: 7740: 7739: 7735: 7734: 7731: 7727: 7724: 7721: 7720:Neoceratopsia 7716: 7706: 7705: 7701: 7699: 7698: 7694: 7692: 7691: 7687: 7685: 7684: 7680: 7678: 7677: 7673: 7672: 7670: 7668: 7664: 7658: 7657: 7653: 7651: 7650: 7646: 7644: 7643: 7639: 7638: 7635: 7631: 7628: 7625: 7620: 7616: 7612: 7607: 7603: 7578: 7577: 7576: 7575: 7573: 7571: 7567: 7559: 7555: 7554: 7553: 7552: 7549: 7546: 7544: 7540: 7532: 7528: 7527: 7526: 7525: 7522: 7519: 7517: 7513: 7509: 7501: 7497: 7494: 7492: 7488: 7485: 7483: 7479: 7476: 7474: 7470: 7468: 7464: 7463: 7458: 7454: 7450: 7443: 7438: 7436: 7431: 7429: 7424: 7423: 7420: 7413: 7408: 7404: 7403: 7399: 7391: 7386: 7385: 7376: 7373: 7368: 7364: 7360: 7356: 7352: 7348: 7344: 7337: 7335: 7331: 7327:(4): 827–833. 7326: 7322: 7315: 7313: 7304: 7301: 7296: 7292: 7288: 7284: 7280: 7276: 7272: 7268: 7264: 7260: 7253: 7246: 7243: 7238: 7234: 7230: 7226: 7222: 7218: 7214: 7207: 7204: 7192: 7188: 7182: 7179: 7173: 7168: 7164: 7157: 7155: 7146: 7144: 7140: 7135: 7131: 7127: 7123: 7116: 7113: 7108: 7104: 7100: 7096: 7092: 7088: 7084: 7080: 7079:Palaeontology 7073: 7071: 7062: 7059: 7054: 7050: 7045: 7040: 7036: 7032: 7028: 7024: 7020: 7018: 7009: 7006: 7001: 6994: 6991: 6986: 6980: 6976: 6972: 6965: 6962: 6957: 6953: 6949: 6945: 6941: 6937: 6933: 6929: 6925: 6921: 6914: 6911: 6906: 6902: 6898: 6894: 6887: 6885: 6881: 6876: 6872: 6867: 6862: 6857: 6852: 6848: 6844: 6840: 6836: 6832: 6825: 6822: 6817: 6813: 6808: 6803: 6799: 6795: 6791: 6787: 6783: 6776: 6773: 6768: 6764: 6760: 6756: 6752: 6748: 6744: 6740: 6733: 6730: 6725: 6721: 6717: 6713: 6709: 6702: 6699: 6694: 6690: 6689:Protiguanodon 6686: 6679: 6676: 6671: 6667: 6662: 6657: 6652: 6647: 6643: 6639: 6635: 6628: 6625: 6620: 6616: 6611: 6606: 6602: 6598: 6594: 6590: 6586: 6582: 6581:Palaeontology 6578: 6576: 6567: 6564: 6559: 6555: 6548: 6545: 6540: 6536: 6532: 6528: 6524: 6520: 6516: 6512: 6504: 6501: 6496: 6492: 6487: 6482: 6478: 6474: 6470: 6466: 6462: 6458: 6454: 6447: 6444: 6431: 6427: 6421: 6418: 6406: 6402: 6395: 6392: 6387: 6383: 6378: 6373: 6369: 6365: 6361: 6357: 6353: 6349: 6345: 6338: 6335: 6330: 6326: 6321: 6316: 6312: 6308: 6304: 6300: 6296: 6289: 6287: 6283: 6278: 6274: 6269: 6264: 6260: 6256: 6252: 6248: 6244: 6237: 6234: 6231: 6228:(2001): 147. 6227: 6223: 6217: 6214: 6209: 6205: 6201: 6197: 6193: 6189: 6185: 6181: 6177: 6173: 6166: 6164: 6155: 6153: 6151: 6149: 6145: 6142: 6139:(2001): 571. 6138: 6134: 6128: 6125: 6120: 6116: 6112: 6108: 6101: 6099: 6095: 6090: 6086: 6082: 6078: 6074: 6067: 6065: 6063: 6059: 6054: 6052:9780122268106 6048: 6044: 6039: 6038: 6029: 6027: 6023: 6018: 6014: 6010: 6006: 6002: 5998: 5994: 5990: 5988: 5979: 5976: 5963: 5956: 5954: 5950: 5945: 5941: 5937: 5933: 5929: 5925: 5921: 5917: 5913: 5909: 5905: 5898: 5895: 5890: 5886: 5882: 5878: 5874: 5870: 5866: 5859: 5857: 5855: 5853: 5849: 5844: 5840: 5836: 5832: 5828: 5824: 5820: 5816: 5812: 5808: 5801: 5794: 5792: 5790: 5786: 5781: 5777: 5772: 5767: 5763: 5759: 5755: 5751: 5747: 5740: 5738: 5736: 5732: 5727: 5723: 5718: 5713: 5709: 5705: 5698: 5696: 5687: 5685: 5681: 5676: 5672: 5668: 5664: 5660: 5656: 5652: 5648: 5644: 5637: 5634: 5629: 5625: 5620: 5615: 5610: 5605: 5601: 5597: 5594:(8): e69265. 5593: 5589: 5585: 5578: 5576: 5574: 5570: 5565: 5561: 5557: 5553: 5549: 5545: 5541: 5537: 5530: 5528: 5524: 5519: 5515: 5508: 5506: 5502: 5497: 5493: 5489: 5485: 5481: 5477: 5470: 5468: 5459: 5456: 5451: 5447: 5443: 5439: 5435: 5431: 5423: 5420: 5415: 5407: 5404: 5399: 5395: 5391: 5387: 5383: 5379: 5375: 5371: 5364: 5357: 5354: 5349: 5345: 5341: 5337: 5336: 5331: 5324: 5322: 5320: 5318: 5316: 5314: 5312: 5310: 5306: 5301: 5297: 5290: 5288: 5284: 5279: 5275: 5271: 5267: 5263: 5259: 5252: 5250: 5248: 5246: 5244: 5242: 5240: 5238: 5236: 5232: 5227: 5223: 5219: 5215: 5211: 5207: 5203: 5199: 5195: 5188: 5186: 5184: 5182: 5180: 5178: 5176: 5174: 5170: 5165: 5161: 5157: 5150: 5147: 5142: 5138: 5137:Palaeontology 5134: 5127: 5125: 5121: 5116: 5112: 5108: 5104: 5100: 5096: 5089: 5086: 5081: 5077: 5073: 5069: 5065: 5061: 5057: 5053: 5049: 5042: 5040: 5038: 5034: 5029: 5025: 5021: 5017: 5013: 5009: 5005: 4998: 4995: 4990: 4986: 4982: 4978: 4974: 4967: 4965: 4963: 4961: 4959: 4955: 4950: 4948:9780122268106 4944: 4940: 4935: 4934: 4925: 4922: 4917: 4915:9780521554763 4911: 4907: 4902: 4901: 4891: 4889: 4887: 4883: 4878: 4871: 4869: 4867: 4865: 4863: 4861: 4859: 4855: 4850: 4844:(2): 275–284. 4843: 4839: 4832: 4825: 4823: 4821: 4817: 4812: 4806: 4803: 4798: 4796:9780521366724 4792: 4788: 4783: 4782: 4776: 4769: 4767: 4765: 4763: 4761: 4757: 4752: 4748: 4747:Palaeontology 4744: 4737: 4735: 4733: 4729: 4724: 4722:9780520242098 4718: 4714: 4709: 4708: 4699: 4697: 4695: 4693: 4691: 4689: 4687: 4685: 4683: 4681: 4679: 4677: 4673: 4668: 4664: 4657: 4655: 4651: 4646: 4642: 4635: 4632: 4627: 4623: 4616: 4614: 4612: 4610: 4606: 4602: 4598: 4593: 4590: 4585: 4581: 4574: 4572: 4570: 4566: 4561: 4557: 4553: 4549: 4542: 4540: 4538: 4534: 4529: 4525: 4518: 4515: 4510: 4506: 4499: 4497: 4495: 4493: 4491: 4489: 4487: 4485: 4483: 4481: 4479: 4477: 4475: 4473: 4471: 4467: 4462: 4458: 4457:Protiguanodon 4454: 4447: 4445: 4441: 4435: 4430: 4426: 4419: 4417: 4415: 4413: 4409: 4404: 4403: 4395: 4392: 4386: 4382: 4379: 4377: 4374: 4373: 4369: 4358: 4353: 4351: 4349: 4345: 4341: 4337: 4333: 4329: 4325: 4320: 4318: 4314: 4310: 4306: 4302: 4298: 4294: 4290: 4286: 4282: 4278: 4274: 4270: 4266: 4259: 4255: 4254: 4248: 4241: 4239: 4237: 4233: 4229: 4225: 4221: 4217: 4213: 4212: 4207: 4203: 4195: 4191: 4190: 4184: 4177: 4175: 4173: 4169: 4164: 4160: 4156: 4152: 4148: 4147:bone fracture 4144: 4140: 4136: 4128: 4126: 4122: 4120: 4116: 4111: 4102: 4098: 4096: 4092: 4087: 4078: 4071: 4069: 4067: 4063: 4059: 4055: 4051: 4047: 4043: 4040:reptiles and 4038: 4034: 4029: 4027: 4023: 4019: 4011: 4006: 3999: 3997: 3994: 3990: 3989:Psittacosaurs 3985: 3981: 3977: 3972: 3970: 3965: 3961: 3957: 3953: 3949: 3945: 3937: 3932: 3926:Limb function 3925: 3923: 3919: 3917: 3908: 3904: 3900: 3893: 3891: 3889: 3885: 3881: 3876: 3871: 3869: 3865: 3861: 3860:scleral rings 3857: 3853: 3849: 3845: 3844: 3843:Protoceratops 3839: 3835: 3830: 3826: 3822: 3815: 3810: 3806: 3804: 3800: 3799: 3798:Tyrannosaurus 3794: 3790: 3786: 3782: 3778: 3774: 3770: 3766: 3763:The brain of 3758: 3754: 3747: 3745: 3743: 3733: 3732: 3724: 3723: 3715: 3714: 3706: 3705: 3697: 3696: 3688: 3687: 3679: 3678: 3675: 3674: 3673: 3666: 3665: 3662: 3661: 3658: 3657: 3656: 3649: 3648: 3642: 3641: 3638: 3637: 3634: 3633: 3632: 3631:P. ordosensis 3625: 3624: 3618: 3617: 3614: 3613: 3610: 3609: 3608: 3601: 3600: 3594: 3593: 3590: 3589: 3586: 3585: 3584: 3577: 3576: 3570: 3569: 3566: 3565: 3557: 3556: 3553: 3552: 3551: 3544: 3543: 3540: 3539: 3536: 3535: 3534: 3527: 3526: 3520: 3519: 3513: 3512: 3509: 3508: 3500: 3499: 3496: 3495: 3494: 3487: 3486: 3483: 3482: 3479: 3478: 3477: 3470: 3469: 3463: 3462: 3456: 3455: 3451: 3450: 3446: 3444: 3440: 3436: 3432: 3428: 3421: 3417: 3412: 3403: 3402: 3394: 3393: 3385: 3384: 3376: 3375: 3367: 3366: 3358: 3357: 3349: 3348: 3340: 3339: 3331: 3330: 3322: 3321: 3313: 3312: 3309: 3308: 3302: 3301: 3298: 3297: 3294: 3293: 3287: 3286: 3280: 3279: 3276: 3275: 3272: 3271: 3270: 3269:Koreaceratops 3263: 3262: 3256: 3255: 3252: 3251: 3243: 3242: 3239: 3238: 3237: 3230: 3229: 3226: 3225: 3222: 3221: 3220: 3219:Helioceratops 3213: 3212: 3206: 3205: 3199: 3198: 3195: 3194: 3186: 3185: 3182: 3181: 3180: 3173: 3172: 3169: 3168: 3165: 3164: 3163: 3156: 3155: 3149: 3148: 3142: 3141: 3138: 3137: 3134: 3133: 3132: 3125: 3124: 3118: 3117: 3114: 3113: 3110: 3109: 3108: 3101: 3100: 3094: 3093:Neoceratopsia 3091: 3090: 3087: 3086: 3078: 3077: 3074: 3073: 3072: 3065: 3064: 3061: 3060: 3057: 3056: 3055: 3048: 3047: 3041: 3040: 3036: 3035: 3029: 3028: 3025: 3024: 3016: 3015: 3012: 3011: 3010: 3003: 3002: 2999: 2998: 2995: 2994: 2993: 2986: 2985: 2979: 2978: 2972: 2971: 2968: 2967: 2964: 2963: 2962: 2955: 2954: 2948: 2945: 2944: 2941: 2940: 2937: 2936: 2935: 2928: 2925: 2924: 2918: 2915: 2914: 2910: 2908: 2907: 2902: 2898: 2894: 2890: 2885: 2883: 2879: 2875: 2871: 2867: 2866: 2861: 2857: 2853: 2849: 2845: 2844: 2839: 2835: 2831: 2824: 2820: 2812: 2805: 2803: 2801: 2797: 2793: 2789: 2785: 2781: 2777: 2773: 2769: 2765: 2761: 2756: 2753: 2752:P. ordosensis 2749: 2745: 2741: 2737: 2733: 2729: 2725: 2721: 2717: 2713: 2709: 2705: 2701: 2697: 2693: 2689: 2685: 2681: 2677: 2673: 2669: 2665: 2661: 2658: 2654: 2650: 2646: 2642: 2638: 2634: 2630: 2626: 2622: 2618: 2614: 2610: 2608: 2604: 2600: 2599: 2594: 2590: 2586: 2582: 2578: 2574: 2570: 2566: 2562: 2558: 2554: 2550: 2546: 2544: 2540: 2536: 2532: 2528: 2524: 2520: 2516: 2512: 2503: 2496: 2494: 2492: 2488: 2484: 2480: 2475: 2471: 2466: 2464: 2460: 2456: 2452: 2451: 2450:Beipiaosaurus 2446: 2445: 2439: 2430: 2426: 2424: 2420: 2417: 2412: 2408: 2404: 2400: 2399:countershaded 2396: 2391: 2388: 2384: 2379: 2375: 2370: 2368: 2364: 2360: 2356: 2352: 2348: 2347: 2342: 2337: 2335: 2331: 2327: 2323: 2319: 2315: 2301: 2292: 2285: 2275: 2267: 2265: 2263: 2259: 2255: 2251: 2247: 2243: 2239: 2235: 2231: 2227: 2223: 2219: 2218:ornithischian 2215: 2212:The skull of 2207: 2202: 2198: 2196: 2192: 2188: 2184: 2180: 2176: 2172: 2171:P. ordosensis 2168: 2164: 2160: 2156: 2152: 2148: 2144: 2140: 2136: 2132: 2128: 2120: 2115: 2108: 2106: 2104: 2100: 2096: 2092: 2086: 2083: 2082: 2081: 2079: 2075: 2071: 2067: 2064:and American 2063: 2059: 2055: 2051: 2047: 2042: 2036: 2033: 2032: 2031: 2029: 2025: 2021: 2017: 2013: 2009: 2005: 2001: 2000: 1995: 1991: 1987: 1983: 1979: 1975: 1971: 1967: 1963: 1959: 1955: 1951: 1947: 1943: 1939: 1935: 1931: 1927: 1923: 1919: 1915: 1911: 1903: 1898: 1891: 1888: 1887: 1886: 1884: 1880: 1876: 1872: 1868: 1864: 1860: 1853: 1850: 1849: 1848: 1846: 1842: 1838: 1834: 1830: 1826: 1822: 1818: 1814: 1813:Zhou Chang-Fu 1810: 1804: 1801: 1800: 1799: 1796: 1792: 1788: 1784: 1780: 1776: 1772: 1765: 1762: 1761: 1760: 1758: 1754: 1750: 1746: 1742: 1738: 1734: 1730: 1726: 1722: 1718: 1714: 1707: 1704: 1703: 1702: 1700: 1696: 1695:P. ordosensis 1692: 1691:P. ordosensis 1688: 1684: 1679: 1675: 1674:P. ordosensis 1671: 1667: 1663: 1659: 1655: 1647: 1646:P. ordosensis 1643: 1640: 1639: 1638: 1636: 1635: 1630: 1626: 1622: 1618: 1614: 1607: 1604: 1603: 1602: 1600: 1596: 1592: 1585: 1581: 1577: 1571: 1568: 1567: 1566: 1564: 1559: 1555: 1551: 1544: 1541: 1540: 1539: 1537: 1533: 1529: 1525: 1521: 1517: 1513: 1509: 1505: 1501: 1497: 1493: 1489: 1482: 1479: 1478: 1477: 1475: 1471: 1466: 1465:morphological 1462: 1457: 1453: 1449: 1445: 1441: 1434: 1429: 1422: 1420: 1418: 1414: 1410: 1406: 1405:Guyang County 1402: 1401: 1396: 1392: 1388: 1384: 1380: 1376: 1372: 1367: 1365: 1361: 1358:of the Early 1357: 1354: 1350: 1346: 1343: 1339: 1333: 1331: 1327: 1323: 1319: 1315: 1311: 1307: 1302: 1300: 1296: 1292: 1288: 1285:and possibly 1284: 1280: 1276: 1272: 1268: 1264: 1260: 1256: 1252: 1248: 1244: 1240: 1236: 1235:Protiguanodon 1232: 1227: 1223: 1219: 1215: 1211: 1207: 1203: 1196: 1191: 1187: 1185: 1181: 1177: 1173: 1169: 1165: 1161: 1157: 1153: 1149: 1145: 1141: 1137: 1133: 1129: 1125: 1120: 1118: 1114: 1113:Birger Bohlin 1110: 1106: 1102: 1101:Protiguanodon 1098: 1094: 1090: 1086: 1085:Protiguanodon 1082: 1078: 1074: 1070: 1066: 1062: 1058: 1050: 1046: 1042: 1038: 1035: 1031: 1027: 1023: 1019: 1018:Protiguanodon 1015: 1011: 1007: 1003: 1002:Protiguanodon 998: 996: 992: 988: 987:Protiguanodon 984: 980: 976: 972: 968: 964: 960: 959:Protiguanodon 956: 955:Protiguanodon 952: 948: 944: 943:Protiguanodon 940: 939:Protiguanodon 936: 932: 928: 924: 920: 916: 912: 908: 904: 900: 897: 893: 889: 885: 881: 877: 873: 869: 865: 861: 857: 853: 845: 841: 840:Protiguanodon 837: 833: 827: 823: 819: 815: 808: 806: 804: 801: 797: 793: 792:fossil record 789: 786: 782: 778: 774: 770: 768: 764: 760: 759:North America 756: 755: 750: 746: 742: 738: 734: 733: 728: 727: 722: 718: 715: 711: 710: 705: 701: 697: 693: 689: 685: 681: 677: 673: 669: 665: 662: 659: 655: 651: 648: 644: 643: 630: 585: 584: 571: 567: 563: 558: 555: 549: 548:Protiguanodon 546: 545: 543: 540: 536: 528: 522: 521: 514: 508: 507: 500: 496: 493: 488: 487: 480: 476: 473: 468: 467: 460: 456: 451: 450: 443: 437: 436: 435:P. ordosensis 429: 425: 420: 419: 412: 408: 404: 399: 398: 390: 386: 383:Sereno & 380: 379: 372: 368: 365: 360: 359: 352: 348: 343: 342: 335: 326: 321: 314: 313: 305: 302: 298: 291: 290: 283: 280: 279: 274: 269: 263: 260: 259: 256: 250: 247: 244: 243: 240: 234: 231: 228: 227: 224: 218: 215: 212: 211: 208: 202: 199: 196: 195: 192: 189: 186: 183: 182: 179: 176: 173: 172: 169: 166: 163: 162: 159: 156: 153: 152: 147: 142: 138: 135: 131: 127: 123: 118: 111: 106: 101: 96: 91: 86: 81: 76: 71: 66: 61: 56: 50: 47:125–105 43: 37: 33: 30: 19: 8894:Yixian fauna 8841: 8732: 8645: 8640:Stellasaurus 8638: 8631: 8624: 8603: 8596: 8591:Coronosaurus 8589: 8584:Centrosaurus 8582: 8553: 8546: 8539: 8532: 8525: 8505: 8500:Lokiceratops 8498: 8491: 8473:Xenoceratops 8471: 8464: 8459:Sinoceratops 8457: 8450: 8443: 8436: 8408: 8401: 8394: 8386: 8379: 8372: 8367:Nedoceratops 8365: 8358: 8340:Vagaceratops 8338: 8333:Utahceratops 8331: 8326:Terminocavus 8324: 8317: 8310: 8303: 8296: 8289: 8282: 8277:Judiceratops 8275: 8268: 8263:Chasmosaurus 8261: 8254: 8247: 8240: 8233: 8226: 8202: 8195: 8188: 8181: 8174: 8167: 8155:Ceratopsidae 8142:Ceratopsidae 8073:Ceratopsidae 8062:Zuniceratops 8060: 8053: 8047:Ajkaceratops 8045: 8021: 8014: 8009:Bagaceratops 8007: 8001:Ajkaceratops 7999: 7983:Coronosauria 7970: 7963: 7956: 7949: 7942: 7935: 7928: 7921: 7914: 7907: 7900: 7893: 7888:Asiaceratops 7886: 7866: 7854:Euceratopsia 7837:Yamaceratops 7835: 7828: 7821: 7801: 7794: 7789:Microceratus 7787: 7782:Liaoceratops 7780: 7772: 7765: 7758: 7751: 7744: 7738:Ajkaceratops 7736: 7702: 7695: 7688: 7681: 7674: 7655: 7654: 7647: 7640: 7558:Ornithischia 7543:Ornithischia 7495: 7491:Ornithischia 7486: 7477: 7383: 7375: 7350: 7346: 7342: 7324: 7320: 7311: 7303: 7262: 7258: 7245: 7220: 7216: 7212: 7206: 7194:. Retrieved 7190: 7181: 7162: 7153: 7125: 7121: 7115: 7082: 7078: 7069: 7061: 7026: 7022: 7016: 7008: 6993: 6974: 6970: 6964: 6923: 6919: 6913: 6896: 6892: 6838: 6834: 6824: 6789: 6785: 6775: 6742: 6738: 6732: 6715: 6711: 6707: 6701: 6695:(127): 1–16. 6692: 6688: 6684: 6678: 6641: 6637: 6627: 6584: 6580: 6574: 6566: 6557: 6547: 6517:(1): 27–34. 6514: 6510: 6503: 6460: 6456: 6446: 6436:15 September 6434:. Retrieved 6430:the original 6420: 6410:15 September 6408:. Retrieved 6405:The Guardian 6404: 6394: 6351: 6347: 6337: 6302: 6298: 6250: 6246: 6236: 6225: 6221: 6216: 6175: 6171: 6162: 6136: 6132: 6127: 6110: 6106: 6080: 6076: 6072: 6036: 5992: 5986: 5978: 5966:. Retrieved 5911: 5907: 5903: 5897: 5872: 5868: 5864: 5810: 5806: 5753: 5749: 5707: 5703: 5694: 5650: 5646: 5642: 5636: 5591: 5587: 5539: 5535: 5517: 5513: 5479: 5475: 5466: 5458: 5433: 5429: 5422: 5413: 5406: 5373: 5369: 5356: 5339: 5333: 5329: 5299: 5295: 5261: 5257: 5201: 5197: 5193: 5163: 5159: 5155: 5149: 5140: 5136: 5132: 5098: 5094: 5088: 5055: 5051: 5047: 5011: 5007: 5003: 4997: 4980: 4976: 4972: 4932: 4924: 4899: 4876: 4841: 4837: 4811: 4805: 4780: 4774: 4750: 4746: 4742: 4706: 4666: 4662: 4644: 4640: 4634: 4625: 4621: 4600: 4592: 4583: 4579: 4551: 4547: 4527: 4523: 4517: 4508: 4504: 4463:(127): 1–16. 4460: 4456: 4452: 4427:(13): 1–10. 4424: 4401: 4394: 4335: 4323: 4321: 4316: 4312: 4288: 4272: 4268: 4264: 4263: 4251: 4231: 4219: 4209: 4201: 4199: 4193: 4187: 4142: 4134: 4132: 4123: 4118: 4109: 4107: 4085: 4083: 4061: 4052:mammals. An 4036: 4033:histological 4030: 4021: 4017: 4015: 4009: 3992: 3988: 3983: 3979: 3975: 3973: 3968: 3963: 3959: 3951: 3947: 3943: 3941: 3935: 3920: 3912: 3902: 3887: 3874: 3872: 3863: 3855: 3847: 3841: 3837: 3820: 3818: 3813: 3802: 3796: 3792: 3788: 3784: 3780: 3768: 3764: 3762: 3756: 3748:Paleobiology 3741: 3739: 3671: 3670: 3669: 3654: 3653: 3652: 3630: 3629: 3628: 3606: 3605: 3604: 3582: 3581: 3580: 3549: 3548: 3547: 3532: 3531: 3530: 3493:P. sibiricus 3492: 3491: 3490: 3475: 3474: 3473: 3453: 3452: 3431:phylogenetic 3426: 3424: 3415: 3307:Coronosauria 3305: 3290: 3267: 3266: 3234: 3233: 3217: 3216: 3179:Yamaceratops 3177: 3176: 3160: 3159: 3129: 3128: 3107:Liaoceratops 3105: 3104: 3070: 3069: 3068: 3053: 3052: 3051: 3038: 3037: 3007: 3006: 2990: 2989: 2959: 2958: 2932: 2931: 2904: 2901:Coronosauria 2892: 2888: 2886: 2863: 2859: 2856:plesiomorphy 2851: 2841: 2829: 2828: 2823:P. sibiricus 2822: 2799: 2791: 2788:P. gobiensis 2787: 2783: 2780:P. sibiricus 2779: 2775: 2771: 2768:P. sibiricus 2767: 2763: 2759: 2757: 2751: 2747: 2743: 2731: 2728:frontal bone 2723: 2719: 2715: 2712:P. sibiricus 2711: 2707: 2703: 2700:P. sibiricus 2699: 2695: 2691: 2687: 2675: 2663: 2662: 2656: 2652: 2648: 2644: 2640: 2632: 2625:P. sibiricus 2624: 2616: 2613:P. sibiricus 2612: 2611: 2606: 2596: 2589:P. sibiricus 2588: 2576: 2573:P. sibiricus 2572: 2568: 2557:premaxillary 2552: 2548: 2547: 2538: 2534: 2530: 2526: 2510: 2508: 2490: 2478: 2473: 2467: 2448: 2442: 2435: 2422: 2418: 2394: 2392: 2386: 2377: 2371: 2346:Chasmosaurus 2344: 2338: 2317: 2311: 2258:P. sibiricus 2257: 2245: 2233: 2229: 2213: 2211: 2205: 2190: 2186: 2183:P. sibiricus 2182: 2178: 2174: 2170: 2166: 2162: 2158: 2154: 2150: 2146: 2142: 2134: 2126: 2124: 2118: 2094: 2090: 2089: 2084: 2077: 2057: 2049: 2045: 2041:P. gobiensis 2040: 2039: 2035:P. gobiensis 2034: 2027: 2026:rather than 2023: 2019: 2015: 2011: 2007: 2003: 1999:nomen dubium 1997: 1993: 1989: 1985: 1981: 1973: 1969: 1966:Wang Xiaolin 1949: 1941: 1933: 1925: 1921: 1913: 1909: 1907: 1901: 1889: 1882: 1878: 1874: 1870: 1866: 1862: 1858: 1856: 1851: 1844: 1840: 1836: 1832: 1828: 1824: 1820: 1808: 1807: 1802: 1783:P. sibiricus 1782: 1770: 1768: 1764:P. sibiricus 1763: 1756: 1752: 1749:nomen dubium 1748: 1744: 1728: 1716: 1711: 1705: 1699:nomen dubium 1698: 1694: 1690: 1686: 1682: 1673: 1664:, after the 1661: 1658:Dale Russell 1653: 1651: 1645: 1641: 1632: 1628: 1624: 1610: 1605: 1590: 1588: 1579: 1569: 1563:Tugulu Group 1553: 1547: 1542: 1535: 1531: 1527: 1523: 1519: 1511: 1507: 1503: 1487: 1485: 1480: 1469: 1451: 1447: 1444:monospecific 1439: 1437: 1433:P. sibiricus 1432: 1416: 1412: 1408: 1400:nomen dubium 1398: 1394: 1390: 1386: 1382: 1378: 1374: 1370: 1368: 1337: 1334: 1329: 1325: 1321: 1313: 1303: 1298: 1294: 1290: 1286: 1282: 1278: 1274: 1270: 1266: 1262: 1258: 1254: 1250: 1246: 1242: 1238: 1234: 1230: 1225: 1217: 1209: 1199: 1194: 1183: 1175: 1171: 1167: 1155: 1135: 1131: 1121: 1116: 1104: 1100: 1084: 1080: 1076: 1068: 1054: 1048: 1025: 1017: 1013: 1005: 1001: 999: 986: 983:Ankylosauria 978: 962: 958: 954: 946: 942: 938: 926: 922: 910: 849: 839: 835: 821: 799: 785:reproductive 780: 772: 771: 766: 762: 752: 748: 736: 730: 724: 720: 719: 713: 707: 699: 582: 581: 580: 556: 552:Osborn, 1923 547: 526: 519: 518: 506:P. gobiensis 505: 504: 494: 485: 484: 474: 472:Leshchinskiy 466:P. sibiricus 465: 464: 448: 447: 434: 433: 417: 416: 396: 395: 377: 376: 366: 357: 356: 340: 339: 317:Osborn, 1923 311: 310: 301:Type species 294:Osborn, 1923 288: 287: 267: 245: 229: 213: 207:Ornithischia 197: 184: 129: 35: 29: 8757:Wikispecies 8633:Einiosaurus 8527:Avaceratops 8410:Triceratops 8374:Ojoceratops 8197:Monoclonius 7909:Ferrisaurus 7774:Kulceratops 7388:. pp. 7223:: 321–340. 7128:: 325–383. 6893:Palaeoworld 6638:BMC Biology 5342:: 100–114. 5335:Palaeoworld 4309:sedimentary 4236:R-selection 4224:carnivorous 4216:triconodont 4192:, juvenile 4060:remains of 4000:Growth rate 3996:evolution. 3907:gastroliths 3884:gastroliths 3789:Triceratops 3476:P. sinensis 3443:Paul Sereno 3420:Dinosaurium 3054:P. sinensis 2796:postorbital 2776:P. sinensis 2724:P. sinensis 2641:P. sinensis 2633:P. sinensis 2607:P. sinensis 2585:postorbital 2549:P. sinensis 2359:keratinized 2163:P. sinensis 2139:kilogrammes 2121:to a human. 2109:Description 2091:P. amitabha 2085:P. amitabha 2066:Jack Horner 1954:Hou Lianhai 1687:P. sinensis 1550:Paul Sereno 1524:P. sinensis 1504:P. sinensis 1481:P. sinensis 1342:sedimentary 1330:P. sinensis 1279:P. sinensis 1195:P. sinensis 1083:instead of 1057:Haratologay 951:jugal bones 844:gastroliths 726:Triceratops 661:ceratopsian 520:P. amitabha 341:P. sinensis 8848:Categories 8696:See also: 8403:Torosaurus 8319:Spiclypeus 8169:Agathaumas 8082:see below↓ 7902:Cerasinops 7690:Stenopelix 7624:Ceratopsia 7611:Ceratopsia 7579:see below↓ 7570:Ceratopsia 7482:Dinosauria 7449:Ceratopsia 6644:(1). 132. 6560:: 535–544. 5520:: 663–668. 5143:: 801–812. 4669:: 349–360. 4647:: 783–788. 4597:Bohlin, B. 4387:References 4319:biochron. 4214:, a large 4186:Fossil of 4058:fossilized 3878:with long 3868:cathemeral 3439:Hai-Lu You 3418:skeleton, 2947:Ceratopsia 2934:Stegoceras 2878:archosaurs 2834:type genus 2680:neck frill 2672:acetabulum 2637:homologous 2621:neck frill 2509:Skulls of 2444:Tianyulong 2363:homologous 2314:integument 2272:See also: 2234:predentary 1952:, honours 1552:described 1536:P. osborni 1516:Zhao Xijin 1387:P. osborni 1383:P. osborni 1371:P. osborni 1364:hatchlings 1306:Zhao Xijin 1283:P. osborni 1271:P. osborni 1255:P. osborni 969:, and the 919:premaxilla 864:Cretaceous 709:Tianyulong 668:Cretaceous 407:Suteethorn 255:Ceratopsia 191:Dinosauria 7465:Kingdom: 7196:27 August 7107:128781816 6017:199571348 6009:2246/6953 5675:129260211 5564:128771310 5496:237336322 5436:(1): 62. 5080:129687832 4753:: 89–107. 4628:: 53–159. 4434:2246/3267 4293:Barremian 4253:Ordosemys 4178:Predation 4151:infection 4139:pathology 4129:Pathology 4095:precocial 4050:placental 4042:marsupial 3974:However, 3777:allometry 2874:evolution 2629:palpebral 2603:underbite 2483:umbilicus 2149:in size ( 2068:from the 1962:You Hailu 1920:words 紅 ( 1741:Barremian 1721:vertebrae 1593:from the 1528:P. youngi 1520:P. youngi 1476:as well. 1326:P. youngi 1322:P. youngi 1047:skull of 1022:vertebrae 874:. In the 796:east Asia 777:hatchling 403:Buffetaut 164:Kingdom: 158:Eukaryota 8742:Wikidata 8708:Category 8698:Timeline 8204:Polyonax 8190:Dysganus 8183:Ceratops 7746:Aquilops 7473:Chordata 7471:Phylum: 7467:Animalia 7287:15650737 7191:phys.org 7053:23811819 7029:: 2079. 6956:33253407 6948:21493820 6875:25494182 6835:PLOS ONE 6816:16901832 6767:89051352 6670:35672741 6619:89156313 6539:12955841 6495:27641767 6386:27641767 6329:33472049 6277:18182372 6208:17781405 6200:12435037 5944:17781405 5936:12435037 5835:15356619 5780:19535376 5726:55251322 5628:23950887 5588:PLOS ONE 5226:84569578 5166:: 71–73. 4599:(1953). 4586:: 1–554. 4530:: 1–678. 4354:See also 4295:through 4287:bearing 4228:Mesozoic 4159:necrosis 3956:pronated 3934:Mounted 3880:chevrons 3827:. Large 3825:endocast 3583:P. major 3414:Mounted 3131:Aquilops 2906:Aquilops 2598:fenestra 2593:mandible 2531:P. major 2463:follicle 2383:collagen 2367:theropod 1883:P. major 1871:P. major 1852:P. major 1582:fossil, 1395:P. tingi 1379:P. tingi 1267:P. tingi 1259:P. tingi 1222:Shandong 1148:Kemerovo 1077:P. tingi 935:holotype 888:skeleton 872:Mongolia 868:Tertiary 818:Holotype 803:biochron 754:Aquilops 696:Thailand 688:Mongolia 664:dinosaur 652:") is a 568:, & 539:Synonyms 261:Family: 178:Chordata 174:Phylum: 168:Animalia 154:Domain: 8816:4126864 8803:1000094 8790:4823245 8777:4532049 8748:Q132672 8598:Spinops 7916:Gremlin 7704:Yinlong 7355:Bibcode 7295:2306428 7267:Bibcode 7225:Bibcode 7087:Bibcode 7031:Bibcode 6928:Bibcode 6920:Science 6866:4262212 6843:Bibcode 6807:1635516 6747:Bibcode 6661:9172161 6589:Bibcode 6519:Bibcode 6486:5049543 6465:Bibcode 6377:5049543 6356:Bibcode 6307:Bibcode 6268:2596897 6180:Bibcode 5916:Bibcode 5877:Bibcode 5843:4413450 5815:Bibcode 5771:2842669 5655:Bibcode 5619:3739782 5596:Bibcode 5544:Bibcode 5438:Bibcode 5398:1973589 5378:Bibcode 5266:Bibcode 5206:Bibcode 5160:Oryctos 5103:Bibcode 5060:Bibcode 5016:Bibcode 4281:Siberia 4260:, China 3916:gizzard 2961:Yinlong 2870:nostril 2843:Yinlong 2832:is the 2736:ischium 2523:dentary 2519:maxilla 2487:amniote 2459:turkeys 2411:patagia 2334:Germany 2293:R 4970) 2250:derived 2238:keratin 2230:rostral 2222:profile 2074:Montana 2028:P. houi 2016:P. houi 2008:P. houi 2002:within 1994:P. houi 1990:H. houi 1958:curated 1950:H. houi 1890:P. houi 1845:H. houi 1829:H. houi 1713:Xu Xing 1500:Beijing 1206:Laiyang 1152:Siberia 788:biology 757:, from 745:derived 732:Yinlong 694:, and 680:species 658:extinct 525:Napoli 424:Russell 281:Genus: 7293: 7285: 7259:Nature 7105: 7051: 6981: 6954: 6946: 6873: 6863: 6814: 6804: 6765: 6668: 6658: 6617: 6537: 6493: 6483: 6384: 6374: 6327: 6275: 6265: 6222:Nature 6206: 6198: 6133:Nature 6049: 6045:–613. 6015: 5942: 5934: 5841: 5833: 5807:Nature 5778: 5768: 5724: 5673: 5626: 5616: 5562: 5494: 5396: 5224: 5078: 4945: 4941:–699. 4912: 4908:–516. 4793: 4789:–210. 4719: 4715:–493. 4297:Albian 4271:. All 4155:fibula 4115:burrow 4012:, AMNH 2893:et al. 2882:evolve 2726:. The 2698:, and 2651:, and 2591:. The 2470:cloaca 2407:cloaca 2374:dermis 2351:dorsal 2341:scales 2095:et al. 1934:sauros 1747:was a 1474:pelvis 1456:extant 1356:stages 1353:Albian 1349:Aptian 1345:strata 1174:, and 1144:Moscow 933:. 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