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120-566: Psittacosaurus ( / ˌ s ɪ t ə k ə ˈ s ɔːr ə s / SIT -ə-kə- SOR -əs ; " parrot lizard ") is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia , existing between 125 and 105 million years ago . It is notable for being the most species -rich non-avian dinosaur genus. Up to 12 species are known, from across China , Mongolia , Russia , and Thailand . The species of Psittacosaurus were obligate bipeds at adulthood, with

240-465: A nomen dubium . Xu Xing , another Chinese paleontologist, named a new species of Psittacosaurus in 1997, based on a complete skull with associated vertebrae and a forelimb. This material was recovered in Gansu Province , near the border with Inner Mongolia. This species is named P. mazongshanensis after the nearby mountain called Mazongshan (Horse Mane Mountain) and has been described in

360-595: A sagittal crest on the parietal. The second species, P. tingi , was named for partial lower jaws and teeth, which Young only tentatively referred to Psittacosaurus instead of Protiguanodon . Both specimens, stored in the Institute of Vertebrate Paleontology and Paleoanthropology as IVPP RV31039 and IVPP RV31040 respectively, come from the Xinpongnaobao Formation . An additional tooth, partial hand , and fragments of vertebrae and limbs were found in

480-493: A bulbous vertical ridge down the centre of each tooth. Both upper and lower jaws sport a pronounced beak, formed from the rostral and predentary bones, respectively. The bony core of the beak may have been sheathed in keratin to provide a sharp cutting surface for cropping plant material. As the generic name suggests, the short skull and beak superficially resemble those of modern parrots. Psittacosaurus skulls share several adaptations with more derived ceratopsians, such as

600-407: 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. P. xinjiangensis is distinguished by a prominent jugal 'horn' that is flattened on the front end, as well as some features of

720-428: 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 disruptive coloration . The specimen also had dense clusters of pigment on its shoulders, face (possibly for display), and cloaca (which may have had an antimicrobial function, though this has been disputed), as well as large patagia on its hind legs that connected to

840-400: A feature also seen in P. sibiricus . The mandible (lower jaw) lacks the hollow opening, or fenestra , seen in other species, and the entire lower jaw is bowed outwards, giving the animal the appearance of an underbite . The skull of an adult P. sinensis can reach 11.5 centimeters (4.5 in) in length. P. sibiricus is the largest-known species of Psittacosaurus . The skull of

960-426: A high degree of dexterity, in a similar manner to a human using their hands. A study conducted with Australian parrots has demonstrated that they exhibit " handedness ", a distinct preference with regards to the foot used to pick up food, with adult parrots being almost exclusively "left-footed" or "right-footed", and with the prevalence of each preference within the population varying by species. Cockatoo species have

1080-399: A high skull and a robust beak. One individual was found preserved with long filaments on the tail, similar to those of Tianyulong . Psittacosaurus 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. Psittacosaurus was one of

1200-552: A higher aggregate extinction risk ( IUCN Red List Index ) than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperate regions as well. The greatest diversity of parrots is in South America and Australasia . Parrots—along with ravens, crows, jays, and magpies —are among the most intelligent birds, and the ability of some species to imitate human speech enhances their popularity as pets . They form

1320-431: A large dog. The lower mandible is shorter, with a sharp, upward-facing cutting edge, which moves against the flat part of the upper mandible in an anvil-like fashion. Touch receptors occur along the inner edges of the keratinised bill, which are collectively known as the " bill tip organ ", allowing for highly dexterous manipulations. Seed-eating parrots have a strong tongue (containing similar touch receptors to those in

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1440-467: A mobile crest of feathers on the top of their heads, which they can raise for display, and retract. No other parrots can do so, but the Pacific lorikeets in the genera Vini and Phigys can ruffle the feathers of the crown and nape, and the red-fan parrot (or hawk-headed parrot) has a prominent feather neck frill that it can raise and lower at will. The predominant colour of plumage in parrots

1560-633: A new Chinese species of Psittacosaurus was found in the Aptian-Albian Qingshan Formation of Shandong Province , southeast of Beijing . C. C. Young called it P. sinensis to differentiate it from P. mongoliensis , 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 P. mongoliensis . Chinese paleontologist Zhao Xijin named

1680-675: A new locality, Ulan Osh, where a disarticulated specimen of Psittacosaurus mongoliensis 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 Paleontological Institute of Moscow . Soviet excavations near Kemerovo in Siberia also discovered a partial skull and skeleton of multiple individuals referrable to Psittacosaurus . This material

1800-513: A new species after his mentor, C. C. Young, in 1962. However, the type specimen of P. youngi (a partial skeleton and skull) was discovered in the same rocks as P. sinensis and appears to be very similar, so P. youngi is generally considered a junior synonym of that better-known species. As with P. guyangensis and P. osborni , You and Dodson (2004) listed it as valid in a table, but not in their text. In 1988, Zhao and American paleontologist Paul Sereno described P. xinjiangensis , named after

1920-622: A preliminary manner. Unfortunately, the skull was damaged while in the care of the Chinese Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), and several fragments have been lost, including all of the teeth. The remains were found in the Lower Xinminbao Formation , which have not been precisely dated, although there is some evidence that they were deposited in the late Barremian through Aptian stages. Sereno suggested in 2000 that P. mazongshanensis

2040-417: A single known species. The difference is most likely due to artifacts of the fossilisation process. While Psittacosaurus 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 Psittacosaurus can be analysed more completely than that of most dinosaur genera, resulting in

2160-571: 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 P. neimongoliensis was probably smaller than P. mongoliensis , with a proportionately longer skull and tail. P. ordosensis 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. The type skull of P. lujiatunensis measures 19 cm (7.5 in) in length, while

2280-539: A small genus restricted to New Guinea and the Solomon Islands. The superfamily Strigopoidea contains three living species of aberrant parrots from New Zealand. The broad-tailed parrots, subfamily Platycercinae , are restricted to Australia, New Zealand, and the Pacific islands as far eastwards as Fiji . The true parrot superfamily, Psittacoidea, includes a range of species from Australia and New Guinea to South Asia and Africa. The centre of cockatoo biodiversity

2400-509: A strong curved beak , upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genera , found mostly in tropical and subtropical regions. The four families are the Psittaculidae (Old World parrots), Psittacidae (African and New World parrots), Cacatuoidea (cockatoos), and Strigopidae (New Zealand parrots). One-third of all parrot species are threatened by extinction , with

2520-523: A synonym of P. mongoliensis , but noted it was tentative because of the presence of multiple valid psittacosaur species in Inner Mongolia. Young also described the species P. tingi in the same 1931 report which contained P. osborni . It is based on several skull fragments. He later synonymised the two species under the name P. osborni . You and Dodson (2004) followed this in a table, but Sereno regarded both species as synonyms of P. mongoliensis ;

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2640-406: A table in the latter reported P. tingi as a nomen dubium , however. The front half of a skull from Guyang County in Inner Mongolia was described as Psittacosaurus guyangensis 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 P. mongoliensis , it falls within

2760-433: A wide frontal binocular field for a bird, although this is nowhere near as large as primate binocular visual fields. Unlike humans, the vision of parrots is also sensitive to ultraviolet light. Parrots have strong zygodactyl feet (two toes facing forward and two back) with sharp, elongated claws, which are used for climbing and swinging. Most species are capable of using their feet to manipulate food and other objects with

2880-404: Is 30% smaller than P. mongoliensis . The largest are P. lujiatunensis and P. sibiricus , although neither is significantly larger than P. mongoliensis . Psittacosaurus postcranial skeletons are more typical of a 'generic' bipedal ornithischian. There are only four digits on the manus ('hand'), as opposed to the five found in most other ornithischians (including all other ceratopsians), while

3000-748: Is Australia and New Guinea, although some species reach the Solomon Islands (and one formerly occurred in New Caledonia ), Wallacea and the Philippines. Several parrots inhabit the cool, temperate regions of South America and New Zealand . Three species—the thick-billed parrot , the green parakeet , and the now-extinct Carolina parakeet —have lived as far north as the southern United States. Many parrots, especially monk parakeets , have been introduced to areas with temperate climates, and have established stable populations in parts of

3120-441: Is a prominent flange on the lower edge of the dentary, a feature also seen in specimens of P. lujiatunensis , and to a lesser degree in P. mongoliensis , P. sattayaraki , and P. sibiricus . The complete type skull, probably adult, is 13.7 centimetres (5.5 in) long. The dentary of P. sattayaraki has a flange similar to that found in P. mongoliensis , P. sibiricus , P. lujiatunensis and P. meileyingensis , although it

3240-413: Is consistent with its greater geological age. P. gobiensis was small-bodied (one metre (3 ft 3 in) long) and differs from other species of Psittacosaurus by "significant, but structurally minor, details." These include the presence of a pyramidal horn on the postorbital , a depression on the postorbital-jugal contact, and enamel thickness. P. mongoliensis was a contemporary. Psittacosaurus

3360-405: Is green, though most species have some red or another colour in small quantities. Cockatoos, however, are predominately black or white with some red, pink, or yellow. Strong sexual dimorphism in plumage is not typical among parrots, with some notable exceptions, the most striking being the eclectus parrot . However, it has been shown that some parrot species exhibit sexually dimorphic plumage in

3480-399: Is less pronounced than in those species. The material appears to be roughly the same size as P. sinensis . The frontal bone of P. neimongoliensis is distinctly narrow compared to that of other species, resulting in a narrower skull overall. The ischium bone of the pelvis is also longer than the femur , which differs from other species in which these bones are known. The type specimen has

3600-403: Is located on either side of the skull in the circumorbital region. It is the origin of several masticatory muscles in the skull. The jugal and lacrimal bones are the only two remaining from the ancestral circumorbital series: the prefrontal, postfrontal, postorbital, jugal, and lacrimal bones. During development, the jugal bone originates from dermal bone . This bone is considered key in

3720-496: Is not assumed that they belong to the same species. More than 200 specimens of Psittacosaurus have been found in the Yixian Formation, which is famous for its fossils of feathered dinosaurs . 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 Psittacosaurus skeletons were excavated in Mongolia during

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3840-626: Is not from a bird, but from a caenagnathid oviraptorosaur (a non-avian dinosaur with a birdlike beak), as several details of the fossil used to support its identity as a parrot are not actually exclusive to parrots, and it is dissimilar to the earliest-known unequivocal parrot fossils. It is generally assumed that the Psittaciformes were present during the Cretaceous–Paleogene extinction event (K-Pg extinction), 66 mya. They were probably generalised arboreal birds, and did not have

3960-449: Is probably a juvenile, is 15.2 centimetres (6 in) long, and the associated femur 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. P. sinensis is readily distinguished from all other species by numerous features of the skull. Adult skulls are smaller than those of P. mongoliensis and have less teeth. Uniquely,

4080-603: Is regarded as Aptian-Albian in age. A second species described in 1988 by Sereno and Zhao, along with two Chinese colleagues, was P. meileyingensis from the Jiufotang Formation , near the town of Meileyingzi, Liaoning Province , 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

4200-478: Is the type genus of the family Psittacosauridae, which was also named by Osborn in 1923. Psittacosaurids were basal to almost all known ceratopsians except Yinlong and perhaps the Chaoyangsauridae . While Psittacosauridae was an early branch of the ceratopsian family tree, Psittacosaurus itself was probably not directly ancestral to any other groups of ceratopsians. All other ceratopsians retained

4320-648: Is the oldest available name, the researchers argued that because the type specimen of P. lujiatunensis was better preserved, the correct name for this species should be P. lujiatunensis rather than P. houi , which would normally have priority. P. gobiensis 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. These specimens are generally all referred to as Psittacosaurus sp., although it

4440-616: 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. French paleontologist Eric Buffetaut and a Thai colleague, Varavudh Suteethorn , described a partial upper and lower jaw from the Aptian-Albian Khok Kruat Formation of Thailand in 1992, giving it the name P. sattayaraki . In 2000, Sereno questioned

4560-577: The Aptian to Albian stages of the Early Cretaceous Period , 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 hatchlings less than 13 centimetres (5.1 in) long, to very old adults reaching nearly 2 metres (6 ft 7 in) in length. In a 2010 review, Sereno again regarded P. osborni as

4680-580: The Early Miocene around 20 mya. The name 'Psittaciformes' comes from the ancient Greek for parrot, ψιττακός ( 'Psittacus' ), whose origin is unclear. Ctesias (5th century BCE) recorded the name Psittacus after the Indian name for a bird, most likely a parakeet (now placed in the genus Psittacula ). Pliny the Elder (23/24–79 CE) in his Natural History (book 10, chapter 58) noted that

4800-691: The Greek word sauros ("lizard"). This name refers to the ancient Hongshan culture of northeastern China, who lived in the same general area in which the fossil skull of Hongshanosaurus was found. The type and only named species, H. houi , honours Hou Lianhai , a professor at the IVPP in Beijing, who curated the specimen. Genus and species were both named by Chinese paleontologists You Hailu , Xu Xing, and Wang Xiaolin in 2003. Sereno (2010) regarded its distinct proportions as due to crushing and compression of

4920-612: The Hongshanosaurus skulls. He regarded Hongshanosaurus as a junior synonym of Psittacosaurus , and potentially the same as P. lujiatunensis . He did not synonymise the two species because of difficulties with the holotype skull of H. houi , instead considering new combination P. houi a nomen dubium within Psittacosaurus . Sereno's hypothesis was supported by a morphometric study in 2013, which found P. houi and P. lujiatunensis to be synonymous. While P. houi

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5040-527: The Ilek Formation 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. P. lujiatunensis , named in 2006 by Chinese paleontologist Zhou Chang-Fu and three Chinese and Canadian colleagues, is one of the oldest-known species, based on four skulls from

5160-817: The Ordos 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 P. neimongoliensis , this species was discovered in the Eijnhoro Formation. Sereno (2010) found the species as described to be indistinguishable from P. sinensis , another small species, but suggested that additional study of P. ordosensis might reveal diagnostic features. He provisionally designated P. ordosensis

5280-546: The Philippines in the north to Australia and across the Pacific as far as French Polynesia , with the greatest diversity being found in and around New Guinea . The subfamily Arinae encompasses all the neotropical parrots, including the amazons, macaws, and conures, and ranges from northern Mexico and the Bahamas to Tierra del Fuego in the southern tip of South America. The pygmy parrots, tribe Micropsittini , form

5400-544: The Qingshan Formation . Of this material, the nearly complete skeleton and skull IVPP V738 was described as the type of the new species Psittacosaurus sinensis , which was found in a red layer 10 mi (16 km) northwest of Rongyang City in Shandong . Yang also assigned 11 other specimens to the taxon, considering it to be the most diverse Psittacosaurus species known at the time. It was distinguished from

5520-656: The United States (including New York City ), the United Kingdom , Belgium , Spain , and Greece . These birds can be quite successful in introduced areas, such as the non-native population of red-crowned amazons in the U.S. which may rival that of their native Mexico. The only parrot to inhabit alpine climates is the kea , which is endemic to the Southern Alps mountain range on New Zealand's South Island . Jugal bone The jugal bone

5640-608: The Xinjiang Autonomous Region 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 Xinjiang. These specimens come from the upper part of the Tugulu Group , which

5760-647: The Yixian Formation of Liaoning Province , 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 Senckenberg Museum in Germany . It was described while awaiting repatriation; previous repatriation attempts were unsuccessful. Most of the body was covered in scales . Larger scales were arranged in irregular patterns, with numerous smaller scales occupying

5880-429: The buff-faced pygmy parrot , at under 10 g (0.4 oz) in weight and 8 cm (3.1 in) in length, to the hyacinth macaw , at 1 m (3.3 ft) in length, and the kākāpō , at 4.0 kg (8.8 lb) in weight. Among the superfamilies, the three extant Strigopoidea species are all large parrots, and the cockatoos tend to be large birds, as well. The Psittacoidea parrots are far more variable, ranging

6000-754: The fossil record has led to the labelling of Lower Cretaceous sediments of east Asia the Psittacosaurus biochron . In 1922 , American paleontologist Henry Fairfield Osborn took part in the Third Asiatic Expedition of the American Museum of Natural History to discover fossils and geologic formations from the Cretaceous and Tertiary of Mongolia . In the Oshih Formation of the Artsa Bogdo Basin, Wong,

6120-628: The order may have evolved in Gondwana , centred in Australasia. The scarcity of parrots in the fossil record, however, presents difficulties in confirming the hypothesis. There is currently a higher number of fossil remains from the northern hemisphere in the early Cenozoic. Molecular studies suggest that parrots evolved approximately 59 million years ago (Mya) (range 66–51 Mya) in Gondwana. The Neotropical Parrots are monophyletic , and

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6240-472: The pet trade , as well as hunting , habitat loss , and competition from invasive species , has diminished wild populations, with parrots being subjected to more exploitation than any other group of wild birds. As of 2021, about 50 million parrots (half of all parrots) live in captivity, with the vast majority of these living as pets in people's homes. Measures taken to conserve the habitats of some high-profile charismatic species have also protected many of

6360-425: The premaxillary bone contacts the jugal (cheek) bone on the outside of the skull. The jugals flare out sideways, forming ' horns ' proportionally wider than in any other known Psittacosaurus species except P. sibiricus and P. lujiatunensis . Because of the flared cheeks, the skull is actually wider than it is long. A smaller 'horn' is present behind the eye , at the contact of the jugal and postorbital bones,

6480-730: The Barremian Andakhuduk Formation of Mongolia. It is named after Amitabha Buddha . The species of Psittacosaurus vary in size and specific features of the skull and skeleton, but share the same overall body shape. The best-known— P. mongoliensis —can reach 2 metres (6.5 ft) in length. The maximum adult body weight was most likely over 20  kilogrammes (44 lb) in P. mongoliensis . Several species approach P. mongoliensis in size ( P. lujiatunensis , P. neimongoliensis , P. xinjiangensis ), while others are somewhat smaller ( P. sinensis , P. meileyingensis ). The smallest known species, P. ordosensis ,

6600-653: The Indians called the bird "siptaces"; however, no matching Indian name has been traced. Popinjay is an older term for parrots, first used in English in the 1500s. Molecular phylogenetic studies have shown that Psittaciformes form a monophyletic clade that is sister to the Passeriformes : The time calibrated phylogeny indicates that the Australaves diverged around 65  Ma (million years ago) and

6720-580: The Mongolian chauffeur, discovered a nearly complete skull , jaws , and skeleton 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 Khukhtek Formation , of Early Cretaceous Aptian to Albian age. The specimen, catalogued as AMNH 6254, was described in 1924 by Osborn, only partially prepared, who gave it

6840-516: The Psittaciformes diverged from the Passeriformes around 62 Ma. Cariamiformes – seriemas Falconiformes – falcons Passeriformes – songbirds Psittaciformes – parrots Most taxonomists now divide Psittaciformes into four families: Strigopidae (New Zealand parrots), Cacatuidae (Cockatoos), Psittacidae (African and New World parrots) and Psittaculidae (Old World parrots). In 2012 Leo Joseph and collaborators proposed that

6960-659: The Psittacoidea, but the former is now placed at the base of the parrot tree next to the remaining members of the Psittacoidea, as well as all members of the Cacatuoidea. The Cacatuoidea are quite distinct, having a movable head crest, a different arrangement of the carotid arteries, a gall bladder , differences in the skull bones, and lack the Dyck texture feathers that—in the Psittacidae—scatter light to produce

7080-563: The Yixian Formation could be identified as feathers. In 2008, another study was published describing the integument and dermis of Psittacosaurus 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 collagen tissue fibres in Psittacosaurus are complex, virtually identical to all other vertebrates in structure but having an exceptional thickness of about forty layers. As

7200-422: The back of the skull, with a triangular depression, the antorbital fossa , on the outside surface of the maxilla (an upper jaw bone). A flange is present on the lower edge of the dentary (the tooth-bearing bone of the lower jaw), although it is not as prominent as in P. meileyingensis or P. major (= P. lujiatunensis ). P. mongoliensis is among the largest known species. The skull of the type specimen, which

7320-429: 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, depending on differences in the light environment. The authors were unable to determine which species of Jehol Formation Psittacosaurus the specimen belonged to due to

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7440-650: The best assignment for the type material may be Ceratopsia incertae sedis . Two new species of Psittacosaurus were described by Canadian Dale Russell and Zhao in 1996. The first was named P. neimongoliensis , after the Mandarin Chinese name for Inner Mongolia. It is based on a nearly complete fossil skeleton, including most of the skull, found in the Early Cretaceous Ejinhoro Formation with seven other individuals. Russell and Zhao also named P. ordosensis in 1996, after

7560-423: The bill tip organ), which helps to manipulate seeds or position nuts in the bill so that the mandibles can apply an appropriate cracking force. The head is large, with eyes positioned high and laterally in the skull, so the visual field of parrots is unlike any other birds. Without turning its head, a parrot can see from just below its bill tip, all above its head, and quite far behind its head. Parrots also have quite

7680-456: The determination of general traits in cases in which the entire skull has not been found intact (for instance, as with dinosaurs in paleontology ). In some dinosaur genera the jugal also forms part of the lower margin of either the antorbital fenestra or the infratemporal fenestra, or both. Most commonly, this bone articulates with the quadratojugal, the postorbital, the lacrimal , and the maxilla. In horned dinosaurs, like Pentaceratops ,

7800-428: The earliest ceratopsians, but closer to Triceratops than Yinlong . Once in its own family, Psittacosauridae, with other genera like Hongshanosaurus , it is now considered to be senior synonym of the latter and an early offshoot of the branch that led to more derived forms. The genera closely related to Psittacosaurus are all from Asia, with the exception of Aquilops , from North America . The first species

7920-423: The exception of their genus Aquilops are from Asia, meaning the group likely originated there. Stegoceras Yinlong Xuanhuaceratops Chaoyangsaurus P. sinensis P. mongoliensis Liaoceratops Aquilops Auroraceratops Yamaceratops Parrot Parrots ( Psittaciformes ), also known as psittacines ( / ˈ s ɪ t ə s aɪ n z / ), are birds with

8040-417: The fifth digit of the hand, a plesiomorphy or primitive trait, whereas all species of Psittacosaurus had only four digits on the hand. In addition, the antorbital fenestra , an opening in the skull between the eye socket and nostril , was lost during the evolution of Psittacosauridae, but is still found in most other ceratopsians and in fact most other archosaurs . It is considered highly unlikely that

8160-404: The fifth digit or antorbital fenestra would evolve a second time. In 2014, the describers of a new taxon of basal ceratopsian published a phylogenetic analysis encompassing Psittacosaurus . The below cladogram is from their analysis, placing the genus as one of the most primitive ceratopsians. The authors (Farke et al. ) noted that all taxa outside of Leptoceratopsidae and Coronosauria with

8280-495: The first umbilicus (belly button) known from a non-avian dinosaur (the oldest known from an amniote ). Because the specimen is close to sexual maturity, it is likely that the umbilicus probably retained throughout this individual's life and that Psittacosaurus 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. Skulls of P. mongoliensis are flat on top, especially over

8400-400: The fossil record, such as behaviour, or colouration. Therefore, actual species diversity may be much higher than currently recognised in this and other dinosaur genera. As some species are known only from skull material, species of Psittacosaurus are primarily distinguished by features of the skull and teeth. Several species can be recognised by features of the pelvis as well. In the 1950s,

8520-466: The four-toed hindfoot is very similar to many other small ornithischians. The skull of Psittacosaurus is highly modified compared to other ornithischian dinosaurs of its time. Extremely tall in height and short in length, the skull has an almost round profile in some species. The portion in front of the orbit (eye socket) is only 40% of total skull length, shorter than any other known ornithischian. The lower jaws of psittacosaurs are characterised by

8640-452: The full spectrum of sizes shown by the family. The most obvious physical characteristic is the strong, curved, broad bill. The upper mandible is prominent, curves downward, and comes to a point. It is not fused to the skull, which allows it to move independently, and contributes to the tremendous biting pressure the birds are able to exert. A large macaw, for example, has a bite force of 35 kg/cm (500 lb/sq in), close to that of

8760-580: The individual when it died is oriented obliquely, so the structure can be seen better in the right side. Psittacosaurus' 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 approximately 6–7 year old subadult by comparing its femoral length to that of similarly-aged specimens of P. lujiatunensis , and found that it preserves

8880-424: The jugal bone is thick and comes to a point, which has led paleontologists to refer to it as the "jugal horn". The earliest reptiles primitively had a lower temporal bar (also referred to as a temporal arcade) where the posterior of the jugal bone contacts the quadratojugal . This structure has been repeatedly lost and regained in various groups. While the jugal bone is thick and straplike in most other reptiles,

9000-411: The jugal bone is thin and strutlike in birds. This is thought to reduce the weight of the skull and facilitate cranial kinesis . In mammals, including humans, the jugal bone is more commonly referred to as the zygoma. It assists in constructing the facial contour, protecting the eye from damage, and providing attachment sites for facial muscles. The zygoma provides important functions as the origin of

9120-423: 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 P. lujiatunensis . P. major was originally characterised by a proportionately large skull, which was 39% of the length of its torso, compared to 30% in P. mongoliensis , and other features. However, a 2013 study utilising morphometric analysis showed that

9240-497: The largest-known skull is 20.5 centimetres (8 in) long, so this species was similar in size to P. mongoliensis and P. sibiricus . There is a fossa in front of the eye, as in P. mongoliensis . The jugal bones flare outwards widely, making the skull wider than it is long, as seen in P. sinensis . Widely flared jugals are also found in P. sibiricus . Overall, this species is thought to exhibit several primitive characteristics compared to other species of Psittacosaurus , which

9360-495: The less charismatic species living in the same ecosystems . Parrots are the only creatures that display true tripedalism , using their necks and beaks as limbs with propulsive forces equal to or greater than those forces generated by the forelimbs of primates when climbing vertical surfaces. They can travel with cyclical tripedal gaits when climbing. Psittaciform diversity in South America and Australasia suggests that

9480-408: The lower beds of the Yixian Formation , 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. P. lujiatunensis was contemporaneous with another psittacosaurid species, Hongshanosaurus houi , which was found in

9600-617: The most variably sized bird order in terms of length; many are vividly coloured and some, multi-coloured. Most parrots exhibit little or no sexual dimorphism in the visual spectrum. The most important components of most parrots' diets are seeds, nuts, fruit, buds, and other plant material. A few species sometimes eat animals and carrion , while the lories and lorikeets are specialised for feeding on floral nectar and soft fruits. Almost all parrots nest in tree hollows (or nest boxes in captivity), and lay white eggs from which hatch altricial (helpless) young. Trapping wild parrots for

9720-435: The name Psittacosaurus mongoliensis , describing its parrot-like beak on the suggestion of fellow American paleontologist William King Gregory . 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 premaxilla . In the same paper, Osborn also described another new taxon he considered similar to Psittacosaurus , Protiguanodon mongoliense , which

9840-605: 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. Following the discovery of material of psittacosaurids in Haratologay in Inner Mongolia , Yang Zhongjian described two additional species in 1932. Known from a crushed skull and fragmentary lower jaw, Young named Psittacosaurus osborni , distinguished by its small size and lack of

9960-403: The only member of the new subfamily Protiguanodontinae . Osborn published an additional description of the specimens of Protiguanodon and Psittacosaurus in 1924 , 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

10080-520: 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 Psittacosaurus . Following similar conclusions to Rozhdestvensky, Yang considered Protiguanodon to be a junior synonym of Psittacosaurus , but retained the species as separate giving former Protiguanodon mongoliense the new species name Psittacosaurus protiguanodonensis , as otherwise both it and Psittacosaurus mongoliensis would have

10200-476: The parrots should be divided into six families. The New Zealand parrots in the genus Nestor were placed in a separate family Nestoridae and the two basal genera in the family Psittaculidae ( Psittrichas and Coracopsis ) were placed in a separate family Psittrichasidae. The two additional families have not been recognised by taxonomists involved in curating lists of world birds and instead only four families are recognised. The following cladogram shows

10320-803: The phylogenetic relationships between the four families. The species numbers are taken from the list maintained by Frank Gill , Pamela Rasmussen and David Donsker on behalf of the International Ornithological Committee (IOC), now the International Ornithologists' Union . Strigopidae – New Zealand parrots (4 species) Cacatuidae – Cockatoos (22 species) Psittacidae – African and New World parrots (179 species) Psittaculidae – Old World parrots (203 species) The Psittaciformes comprise three main lineages: Strigopoidea , Psittacoidea and Cacatuoidea . The Strigopoidea were considered part of

10440-407: The postorbital of P. sinensis are not as pronounced but may be homologous . The jugal has extremely prominent 'horns' and may contact the premaxilla, both features also seen in the possibly related P. sinensis . There is a flange on the dentary of the lower jaw, similar to P. mongoliensis , P. meileyingensis , and P. sattayaraki . It can be told apart from the other species of Psittacosaurus by

10560-514: The quills of Tianyulong , and the sparsely distributed elongated broad filamentous feathers (EBFFs) of Beipiaosaurus . Similar, non-feather-derived bristles are found in a few extant birds such as the "horn" on the horned screamer and the "beards" of turkeys ; these structures differ from feathers in that they are unbranched, heavily cornified and do not develop from a follicle , but instead arise from discrete cell populations that exhibit continuous growth. A 2016 study by Ji Qiang and colleagues

10680-541: 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 P. guyangensis in a table of valid taxa, but did not include it as such in their text. Seventeen species have been referred to the genus Psittacosaurus , 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 monospecific , containing only

10800-490: The recognition of more species. Most extant 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 bones and can only be evaluated from a morphological standpoint, whereas extant species often have very similar skeletal morphology but differ in other ways which would not normally be preserved in

10920-451: The same beds. It is potentially synonymous with H. houi ; Sereno (2010), who proposed that Hongshanosaurus is a synonym of Psittacosaurus , opted to leave P. lujiatunensis and H. houi separate species due to the inadequacies of the latter's type specimen. One nearly complete skeleton of P. lujiatunensis from the same lower beds of the Yixian Formation had previously been classified in its own species, Psittacosaurus major , named for

11040-433: The same locality, with the tooth being referred to Protiguanodon and the remainder of the material being uncertain. Additional Psittacosaurus material from possibly the same locality was described later in 1953 by Birger Bohlin , who considered the remains to likely belong to P. mongoliensis . The Soviet Expeditions into Mongolia from 1946 to 1949 uncovered more material of Psittacosaurus . In 1946 they discovered

11160-596: The same species name. Contrasting Rozhdestvensky, Yang retained the earlier Chinese species P. osborni and P. tingi as separate from P. mongoliensis , but not separate from each other, making P. tingi a junior synonym of P. osborni . Following his new breakdown of species, Yang described the distribution of the genus Psittacosaurus : P. sinensis was the only species known from Shandong; P. osborni and possibly P. mongoliensis were both known from Haratologay (also known as Tebch); P. mongoliensis and P. protiguanodonensis were both known form Oshih; and P. mongoliensis

11280-413: 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 and offered protection against predators. As described in a 2016 study, examination of melanosomes preserved in the specimen of Psittacosaurus preserved with integument indicated that the animal was countershaded , likely related to living in

11400-466: The skeletons of Psittacosaurus and Protiguanodon , including the number of teeth, the number of pre-caudal vertebrae , and other details of the skull and skeleton. Osborn also referred the specimen AMNH 6261 from the Oshih Formation to Psittacosaurus , so the teeth of the two taxa could be compared. It was mentioned in 1932 by American paleontologist Roy Chapman Andrews that AMHN 6254 was

11520-478: The skin nearly to the vertebrae, and were likely circular or tubular before being preserved. Under ultraviolet light , they gave off the same fluorescence as scales, providing the possibility they were keratinized . The study stated that, "at present, there is no convincing evidence which shows these structures to be homologous to the structurally different integumentary filaments of theropod dinosaurs". However, they found that all other feather-like integument from

11640-500: The skull and skeleton. P. youngi was considered to be most similar to P. sinensis , but separated them to bring the count of members of Psittacosauridae to one genus and five species. 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, Psittacosaurus mongoliensis fossils are found in most sedimentary strata dating to

11760-478: The spaces between them, similarly to skin impressions known from other ceratopsians, such as Chasmosaurus . 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 dorsal (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

11880-500: The specialised crushing bills of modern species. Genomic analysis provides strong evidence that parrots are the sister group of passerines , forming the clade Psittacopasserae , which is the sister group of the falcons . The first uncontroversial parrot fossils date to tropical Eocene Europe around 50 mya. Initially, a neoavian named Mopsitta tanta , uncovered in Denmark's Early Eocene Fur Formation and dated to 54 mya,

12000-572: The species have been recognised as the results of the deformation of the skull after fossilisation. Sereno (2010) remained unconvinced of its validity. Beginning in the 1950s, Russian paleontologists began excavating Psittacosaurus remains at a locality near Shestakovo village in Kemerovo Oblast in Western Siberia . Two other nearby localities were explored in the 1990s, one of which produced several complete skeletons. This species

12120-596: The summers of 2005 and 2006 by a team led by Mongolian paleontologist Bolortsetseg Minjin and American Jack Horner from the Museum of the Rockies in Montana . Although only P. mongoliensis has been described from Mongolia so far, these specimens are still in preparation and have not yet been assigned to a species. P. amitabha was named by Napoli et al. in 2019 from a complete skull and partial skeleton. recovered in

12240-430: The supposed differences between P. lujiatunensis and P. major were due to differences in preservation and crushing. The study concluded that both represented a single species. A third species of Lujiatun psittacosaur, the first to be named, was described as Hongshanosaurus houi in 2003. The generic name Hongshanosaurus was derived from the Mandarin Chinese words 紅 ( hóng : "red") and 山 ( shān : "hill"), as well as

12360-410: The teeth. The ilium , one of the three bones of the pelvis, also bears a characteristically long bony process behind the acetabulum (hip socket). An adult femur has a published length of about 16 centimetres (6.3 in). P. meileyingensis has the shortest snout and neck frill of any species, making the skull nearly circular in profile. The orbit (eye socket) is roughly triangular, and there

12480-661: The three major clades originated about 50 Mya (range 57–41 Mya). A single 15 mm (0.6 in) fragment from a large lower bill ( UCMP 143274), found in deposits from the Lance Creek Formation in Niobrara County, Wyoming , had been thought to be the oldest parrot fossil and is presumed to have originated from the Late Cretaceous period, which makes it about 70 million years old. However, other studies suggest that this fossil

12600-664: The tribe Cyclopsittini ) and budgerigar (tribe Melopsittacini). Strigopidae   Cacatuidae Neotropical parrots Psittacinae Psittrichadinae Coracopseinae Psittaculinae Broad-tailed parrots Fig parrots Budgerigar Lories and Lorikeets Bolbopsittacus Hanging parrots Lovebirds Psittacella The order Psittaciformes consists of four families containing roughly 410 species belonging to 101 genera. Superfamily Strigopoidea : New Zealand parrots Superfamily Cacatuoidea : cockatoos Superfamily Psittacoidea : true parrots Living species range in size from

12720-474: The two specimens, Gregory suggested in correspondence that the Protiguanodon specimen could represent a juvenile of Psittacosaurus , based on similarities in size, the parietal bones , and the quadrate bones . Osborn created the new family Psittacosauridae for Psittacosaurus , which he considered possibly related to Ankylosauria , while he placed Protiguanodon within the family Iguanodontidae as

12840-442: 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 neck frill , which is longer than any other species, at 15 to 18% of skull length. A very striking feature of P. sibiricus is the number of 'horns' around the eyes, with three prominences on each postorbital, and one in front of each eye, on the palpebral bones. Similar horns found on

12960-459: The ultraviolet spectrum, normally invisible to humans. Parrots are found on all tropical and subtropical continents and regions including Australia and Oceania , South Asia , Southeast Asia , Central America , South America , and Africa . Some Caribbean and Pacific islands are home to endemic species . By far the greatest number of parrot species come from Australasia and South America. The lories and lorikeets range from Sulawesi and

13080-458: The unique rostral bone at the tip of the upper jaw, and the flared jugal (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 P. sibiricus , but these are thought to be an example of convergent evolution . The integument , or body covering, of Psittacosaurus is known from a Chinese specimen, SMF R 4970, which most likely comes from

13200-458: The validity of this species, citing its eroded and fragmentary nature, and noted an absence of features characteristic of the genus Psittacosaurus . 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

13320-443: The vibrant colours of so many parrots. Colourful feathers with high levels of psittacofulvin resist the feather-degrading bacterium Bacillus licheniformis better than white ones. Lorikeets were previously regarded as a third family, Loriidae, but are now considered a tribe ( Loriini ) within the subfamily Loriinae , family Psittaculidae. The two other tribes in the subfamily are the closely related fig parrots (two genera in

13440-406: The way the skull is preserved, but ruled out P. mongoliensis , based on hip features. Another 2016 study used laser-stimulated fluorescence imaging 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

13560-457: Was a nomen dubium , with no unique features that separate it from any other species of Psittacosaurus . However, more recent authors have noted that it can be distinguished by its proportionally long snout compared to other species of Psittacosaurus , 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

13680-798: Was assigned to the Psittaciformes. However, the rather nondescript bone is not unequivocally psittaciform, and it may rather belong to the ibis genus Rhynchaeites , whose fossil legs were found in the same deposits. Several fairly complete skeletons of parrot-like birds have been found in England and Germany. These are probably not transitional fossils between ancestral and modern parrots, but rather lineages that evolved parallel to true parrots and cockatoos: The earliest records of modern parrots date to around 23–20 mya. The fossil record—mainly from Europe—consists of bones clearly recognisable as belonging to anatomically modern parrots. The Southern Hemisphere contains no known parrot-like remains earlier than

13800-401: Was described by Soviet paleontologist Anatoly Rozhdestvensky in 1955 , who also proposed that Protiguanodon mongoliense , Psittacosaurus osborni , and Psittacosaurus tingi were junior synonyms of Psittacosaurus mongoliensis . In 1958 , Yang published a paper on the dinosaurs of Laiyang , in which he described multiple discoveries of Psittacosaurus from a collection of localities of

13920-491: Was either P. lujiatunensis or closely related, and it may have given rise to later forms of Psittacosaurus . Psittacosaurus 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 hatchling through to adult, which has allowed several detailed studies of Psittacosaurus growth rates and reproductive biology . The abundance of this dinosaur in

14040-489: Was found in the same expedition but from the Ondai Sair Formation . The holotype of Protiguanodon , AMNH 6253, included a nearly complete skeleton found articulated, and partial remains of the skull. While Osborn considered Protiguanodon and Psittacosaurus separate based on the lack of horns on the jugal bones in Protiguanodon , a general dissimilarity in the skeletons, and wide geographic separation of

14160-400: Was named P. sibiricus in 2000 in a scientific paper written by five Russian paleontologists, but credit for the name is officially given to two of those authors, Alexei Voronkevich and Alexander Averianov . 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

14280-595: Was possibly known from Kemerovo. Further discoveries in the Qingshan Formation of Laiyang in 1958 were described by Zhao Xijin in 1962 , giving the new name Psittacosaurus youngi for the specimen BPV.149 in the Beijing Museum of Natural History . Known for a complete skull, partial vertebral series and partial pelvis, P. youngi was distinguished by Zhao by having the shortest skull of all species, vertebral and tooth counts, and various features of

14400-468: 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. A 2021 study of SMF R 4970 examined its cloaca , the first one known from a non-avian dinosaur. The positioning of

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