Psittacosaurus

Before formal naming or identification, this organism was known as the following on this wiki:
**Ilek Formation psittacosaurid**

## Statistics

### Diet

Herbivorous

*Psittacosaurus* is an extinct genus of small ceratopsian dinosaur that lived in Asia during the Early Cretaceous.

## History

*Psittacosaurus* was named in 1923 by Henry Fairfield Osborn with the type species *P. mongoliensis* as the sole genus in the new family Psittacosauridae. The remains were discovered a year earlier during the third American Museum of Natural History expedition to the Gobi Desert. One of the drivers, Wong, discovered AMNH 6254, the holotype, consisting of a near-complete skull and postcrania missing several parts of the limbs. Many other Mongolia, Russian, Chinese, American, Polish, Japanese and Canadian paleontologists have also recovered *P. mongoliensis* from Mongolia and north China. Most individuals are from the Aptian to Albian. Over 75 individuals of *P. mongoliensis* are known including 20 crania and postcrania. Hatchling specimens less than 13 centimeters long are known. Adults were nearly 2 meters long.

In the same paper where he named *Psittacosaurus,* Osborn also named *Protiguanodon*, which is now recognized as a junior synonym of *Psittacosaurus mongoliensis*. The holotype of *Protiguanodon mongoliense*, AMNH 6253, is from the Andakhuduk Formation.

In 1932, Chinese paleontologist CC Young (also romanticized Yang Zhongjian) named *Psittacosaurus osborni* based on a badly damaged skull collected by TH Ting from the Lisangou formation of Inner Mongolia, China. *P. osborni* is most likely a junior synonym of *P. mongoliensis*.

In the same paper where he named *P. osborni*, Young also named *Psittacosaurus tingi*, from the same locality as *P. osborni*. The holotype is a fragmentary lower jaw with some teeth. Young later synonymized *P. tingi* and *P. osborni*, however is is nowadays considered a nomen dubium, though the holotype material most likely represents either *P. osborni* or *P. mongoliensis*.

In 1958, Young recognized that *Protiguanodon* and *Psittacosaurus* represented the same genus. Although the two genera were named in the same paper, the name *Psittacosaurus* was mentioned first and therefore has priority. However, Young did not want to synonymize the two species, and retained the former *Protiguanodon mongoliense* as a species within the genus *Psittacosaurus*. Normally, *mongoliense* would be changed to *mongoliensis*, but that name was already taken by the type species of *Psittacosaurus*, so Young renamed it to *Psittacosaurus protiguanodonensis*. Today, neither the genus *Protiguanodon* nor the species *Psittacosaurus protiguanodonensis* is considered valid, as both are synonyms of *Psittacosaurus mongoliensis*.

In the same paper where he synonymized the genera *Psittacosaurus* and *Protiguanodon*, Young named a new species: *Psittacosaurus sinensis*. This is based on IVPP V738, a nearly complete skeleton from the Doushan Formation of Shandong Province, China. This species is still considered valid.

In 1962, Zhao named another species of *Psittacosaurus* from the same locality as *P. sinensis*: *Psittacosaurus youngi*. The holotype, BNHM BPV149 is a partial skeleton with a well-preserved skull. Zhao did not note any autapomorphies in the description and this species is now considered a junior synonym of *Psittacosaurus sinensis*.

In 1983, Cheng named *Psittacosaurus guyangensis* based on CAGS-IG V351, a partial skull from the Lisangou Formation. This is now considered a junior synonym of *Psittacosaurus mongoliensis*.

In 1988, Sereno and Zhao named *Psittacosaurus xinjiangensis* based on IVPP V7698, a partial skeleton including partial skull from the Tugulu Group of Xinjiang. This species is considered valid.

In a separate paper published in the same 1988 issue of the *Journal of Vertebrate Paleontology*, Sereno et al named *Psittacosaurus meileyingensis* based on IVPP V7705, a partial skull from the Jiufotang Formation (Jehol Group). This species is considered valid.

In 1992, Buffetaut & Suteethorn named *Psittacosaurus sattayaraki* based on TF 2449a, a right dentary from the Khok Kruat Formation in Northeastern Thailand. However, this is now considered a nomen dubium, and the holotype is only referable to Ceratopsia.

In 1996, Russel and Zhao named two species from Inner Mongolia: *Psittacosaurus neimongoliensis* and *Psittacosaurus ordosensis* based on remains from the Ejinhoro Formation near Ordos, Inner Mongolia, China. *Psittacosaurus* *neimongoliensis*, based on holotype IVPP 12-0888-2, a nearly complete skeleton is considered valid. Meanwhile, *Psittacosaurus ordosensis*, based on holotype IVPP 07-0888-1, is a nomen dubium or possibly a junior synonym of *Psittacosaurus sinensis*.

In 1997, Xu named *Psittacosaurus mazongshanensis* based on IVPP V12165, a partial maxilla and lower jaw from the Xinminbao Group in Gansu Province, China. Today, this is considered a nomen dubium.

Psittacosaur remains from near Shestakovo, Siberia in the early 1950s. In the 1990s, two nearby localities yielded several full skeletons named *Psittacosaurus sibiricus* in 2000 by five Russian authors. However, the naming is only attributed to Alexei Voronkevich and Alexander Averianov. In 2006, the remains were fully described. These include 2 articulate skeletons and skulls and disarticulated material from other individuals from the Aptian-Albian of the Ilek Formation. Some sources treat it as a distinct genus.

*Hongshanosaurus houi* was named in 2003 by You et al based on holotype IVPP V12704, a partial juvenile skull from the Yixian Formation (Jehol Group). The genus *Hongshanosaurus* has since been synonymized with *Psittacosaurus. Psittacosaurus houi* is a senior synonym of *Psittacosaurus lujiatunensis* and would normally have priority. However, the name *Psittacosaurus lujiatunensis* is preferred since its holotype is better preserved.

*Psittacosaurus lujiatunensis* was named in 2006 by Zhou et al based on ZMNH M8137, a nearly complete skull from the Yixian Formation. This species is a junior synonym of *Psittacosaurus houi*, but the name *Psittacosaurus lujiatunensis* is preferred due to the better-preserved holotype.

*Psittacosaurus major* was named in 2007 by Sereno et al based on LH PV1, a nearly complete skeleton including the skull from the Yixian Formation. This is a junior synonym of *Psittacosaurus lujiatunensis*.

*Psittacosaurus gobiensis* was named by Sereno et al in 2010 based on LH PV 2, an articulated skeleton from the Bayan Gobi Formation. This species was published as a nomen nudum in 2009, but validly named in 2010. This species is considered valid.

*Psittacosaurus amitabha* was named in 2019 by Napoli et al. based on IGM 100/1132, a complete skull and partial skeleton from the Andakhuduk Formation. It has not been mentioned in the literature since its original description but can be considered valid.

## Description

    *Psittacosaurus* is known from its well preserved fossil specimens, revealing much about the integument, pigmentation and lifestyle of it. The forelimbs were not built for regular quadrupedal movement, as they were not strong enough to produce movement force and could not reach the ground. Juveniles were mostly quadrupedal, and became more bipedal with the passage of time. *Psittacosaurus* also has a boxy head, with a tough beak and large jugals. The tail is long and stocky, with long quills in a bunch on the top, upper section of the tail. There was likely a flap of skin extending from the ankle to the base of the tail. Melanosomes viewed on an illegally smuggled specimen of *Psittacosaurus sp.* reveals the pigmentation of *Psittacosaurus*. *Psittacosaurus* shows countershading; with a beige underside, a black mottled transition and a light brown topside. The underside of one specimen bears an elongate scale row pair that is indicative of an umbilicus, which was probably retained through life as suggested by the specimen's advanced age (or at least until sexual maturity). This structure resembles lizards and crocodilians the most. An umbilicus scar may not have been present in all dinosaurs, due to its variability in reptiles.

    The topside of the tail has light colored quills, which are arranged in a small bunch. The skin was covered in small scales, with patches of larger scales. Some specimens are preserved with gastroliths inside their stomachs. Large numbers of juveniles have been discovered together, meaning that *Psittacosaurus* parents must have given birth to many infants at a time. Specimen SMF R 4970 has an exceptionally preserved cloaca, which even preserves scales around the spot. The scales and pigmentation are unlike the rest of the specimen. The authors of this discovery note that *Psittacosaurus* may have found mates from sight and by smell. They also note the legs and cloaca are covered in calluses, which may be because those areas of the body rub against the rough ground when the animal is in a resting position . *P. mongoliensis* have skulls with a flat top, especially over the back, with a trinagular antorbital fossa on the outside of the maxilla. A flange sits on the lower edge of the dentary. The skull of the type, which is likely a juvenile, is 15.2 centimeters long, which makes it the largest species. The associated femur of the type is 16.2 centimeters long, with larger specimens having a length of 21 centimeters..

*P. sibiricus* is the largest of the group, with the type skull 20.7 centimeters long and the femur 22.3 centimeters. The region where the neck frill would be is 15-18% the skull length. 3 prominences on the palpebral bones and even smaller ones on the postorbitals were situated around the eyes, unlike *Psittacosaurus* (except for *P. sinensis*. which may not even by homologuous and are smaller). It is differentiated by the following autapomorphies (listed by Averianov et al., 2006): laterotemporal fenestra that are subequal in height to the anteroposterior length, postorbitals ventral process that has a subvertical orientation that is ~95° to the posterior process, postorbital with a small dorsal horn, an elarged palpebral subequal in transverse width to the skull roof, a palpebral posterior margin that is almost straight and anterolateral, a predentary with a wedge-shaped silhouette with external margins at ~30°, an arcuate ventral extension on the angular and 14 dorsals (as opposed to the typical 13). A preornital 35% the skull length, a centrolateral pyramidal jugal and no developed maxillary protuberence are features not found in many psittacosaur species. The holotype of *P. sibiricus* is a mature individual with coossified cranial sutures indicating this. Sereno does not use the skull length as a comparative measure, notes the preorbital is subject to change in other taxa, combines the reorientation and straightness of the posterior margin or the palpebral and excluded 3 autapomorphies listed by Averianov et al. (2006) because they were too vague to test. This leaves the premaxilla as deep, the short postorbital medial process and a deep cleft in the posterior ramus of the jugal. The edges of the bones may have been subject to taphonomic breakage before disarticulation, since the premaxilla has thin edges, but there are no signs of breaking. The posterior cleft of the jugal is hard to differentiate from related taxa, so better data is required to determine if it may be used as an autapomorphy.

## Classification

The following cladogram was produced for the description of *P. amitabha* by Napoli et al. (2019), using an incomplete specimen-level dataset. It is the first study to do specimen-level phylogenetics. They recovering their new species as the earliest, but find *P. lujiatunensis* and *P. mongoliensis* specimens to be spread in different specimens, which suggests a composite of specimens mistakenly referred to existing species. They also treat *P. major* as valid since it and *P. lujiatunensis* do not resolve as sister taxa, like they would if they truly were synonymous. They acknowledge that *P. lujiatunensis* and *P. mongoliensis* specimens recovering in different positions may be due to scoring based on description from literature rather than personal observations.

*Psittacosaurus* is currently regarded as the most speciose of the non-avian dinosaur: this article is mainly consisted of data on *P. mongoliensis*, since taxonomy is still unresolved and it may be a candidate for future splitting. It was first placed in Psittacosauridae, which was known as Protiguanodontinae, which was classified by Osborn as a part of Iguanodontidae, as he had thought that *Protiguanodon* was an ancestor of *Iguanodon*.

## Paleoecology

A Psittacosaurus sp. tooth from the Murtoi Formation of Russia bearing sculpted enamel reminiscent of the genus was reassigned to Jeholosauridae indet. in 2022.

## Species

* *P. mongoliensis* (type species)
* *P. sinensis*
* *P. xinjiangensis*
* *P. meileyingensis*
* *P. neimongoliensis*
* *P. sibiricus*
* *P. lujiatunensis*
* *P. gobiensis*
* *P. amitabha*

### Synonyms

* *Protiguanodon* (=*P. mongoliensis*)
* *P. protiguanodonensis* (=*P. mongoliensis)*
* *P. osborni* (=*P. mongoliensis* )
* *P. youngi* (=*P. sinensis*)
* *P. guyangensis* (=*P. mongoliensis*)
* *Hongshanosaurus* (=*P. lujiatunensis*
* *P. houi* (=*P. lujiatunensis*)
* *P. major* (=*P. lujiatunensis)*
* *P. sibericus (lapsus)* (=*P. sibiricus)*
* *P. sibericus* (lapsus) (=*P. sibiricus*)

### Dubious species

* *P. tingi* (=*P. mongoliensis*?)
* *P. sattayaraki* (=Ceratopsia indet.)
* *P. ordosensis* (=*P. sinensis*?)
* *P. mazongshanensis*

## Notable Specimens

* AMNH FR 6254: The holotype of *P. mongoliensis*
* AMNH FR 6253: Holotype of *Protiguanodon*, now recognized as *P. mongoliensis*, a well-preserved, nearly complete skeleton with gastroliths
* IVPP V738: Nearly complete skeleton, holotype of *P. sinensis*.
* VNHM BPV149: Partial skeleton with well preserved skull, holotype of *P. youngi*, now recognized as *P. sinensis*.
* IVPP V7698: Holotype of *Psittacosaurus xinjiangensis*.
* IVPP V7705: Holotype of *Psittacosaurus meileyingensis*.
* IVPP 12-0888-2: Holotype of *Psittacosaurus neimongoliensis*.
* PM TGU 16/4-20: Articulated skeleton with skull, holotype of *P. sibiricus*.
* ZMNH M8137: Holotype of *P. lujiatunensis*.
* LH PV 1: Skull and nearly complete skeleton of *P. lujiatunensis*.
* LH PV 2: Articulated skeleton with skull, holotype of *P. gobiensis*.
* IGM 100/1132: Nearly complete skull and fragmentary postcrania, holotype of *P. amitabha*.
* IVPP V14341: A group of juveniles that died together.
* SMF R 4970 "Frankfurt specimen": A *Psittacosaurus sp.* showing pigmentation, integument and even the cloaca in preservation. The specimen was illegally smuggled out of China before being acquired and scientifically studied
* AMNH FR 6535: A hatchling.
* AMNH FR 6536: Baby slightly older than AMNH FR 6535.

## Gallery

### Fossils

A specimen of *Psittacosaurus* that has gastroliths lodged between its ribs.A close-shot of the gastroliths in the last image.AMNH 6254.
## References

1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40 1.41 An update to psittacosaurid taxonomy
2. ↑ 2.0 2.1 2.2 Osborn, H. F. (1923) Two Lower Cretaceous dinosaurs of Mongolia. *American Museum Novitates*, 95 http://hdl.handle.net/2246/3267
3. ↑ 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.). Materials of the Regional Conference of the Geologists of Siberia, Far East and North East of Russia (in Russian). Tomsk: GalaPress. pp. 363–366.
4. ↑ https://doi.org/10.1017%2Fs1477201906001933
5. ↑ https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-022-01329-9
6. ↑ https://www.sciencedirect.com/science/article/pii/S0960982220318911?dgcid=author
7. ↑ 7.0 7.1 7.2 7.3 https://en.wikipedia.org/wiki/Psittacosaurus
8. ↑ Averianov, Alexander O., Voronkevich, Alexei V., Leshchinskiy, Sergei V. & Fayngertz, Alexei V. (2006). A ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of West Siberia, Russia and its phylogenetic relationships. Journal of Systematic Paleontology 4(4): 359-395. doi 10.1017/S1477201906001933
9. ↑ https://d3qi0qp55mx5f5.cloudfront.net/paulsereno/i/docs/10-IU-Psitt\_Skull-small.pdf?mtime=1591808531
10. ↑ https://www.researchgate.net/publication/334683503\_Psittacosaurus\_amitabha\_a\_New\_Species\_of\_Ceratopsian\_Dinosaur\_from\_the\_Ondai\_Sayr\_Locality\_Central\_Mongolia
11. ↑ https://www.sciencedirect.com/science/article/abs/pii/S0195667122001513
12. ↑ Ilek Formation psittacosaurid
13. ↑ 13.0 13.1 https://paleobiodb.org/classic/basicTaxonInfo?taxon\_no=89029