Open Paleo

Psittacosaurus

Osborn, 1923 SIT-uh-koh-SAWR-us /ˌsɪtəkəˈsɔːrəs/

From Greek psittakos (parrot) and sauros (lizard); meaning "parrot lizard", a name suggested by W.K. Gregory and adopted by Osborn in reference to the deep, edentulous, parrot-like rostrum formed by the premaxillae and the unpaired rostral bone.

143.1–100.5 million years ago Berriasian–Albian, Early Cretaceous
Early Cretaceous stages

Psittacosaurus 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 13 species are known, from across China, Mongolia, Russia, and Thailand. The species of Psittacosaurus were obligate bipeds 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 Tianyulong. Psittacosaurus probably had complex behaviors, 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.

Diagnosis

  1. Skull short and deep, with a prominent parrot-like edentulous rostrum; preorbital skull length less than 40% of total skull length, shorter than in nearly all other ornithischians.
  2. Unpaired median rostral bone forming the anterior keel of the snout, with rostral-nasal contact and the nasal contributing to the internarial bar ventral to the external naris.
  3. Jugals projecting laterally well beyond the dorsal margin of the orbit, bearing a prominent dorsoventral crest on their lateral aspect.
  4. Fenestra of the lacrimal canal present between premaxilla and lacrimal — a condition unique to Psittacosaurus among dinosaurs.
  5. Pterygoid with a neomorphic secondary palatal lamina forming an akinetic basal plate that contacts its opposite at the midline, reinforcing the palate against transverse compression.
  6. Laterally divergent palpebral with transverse posterior margin, projecting laterally to a width equal to the posterior skull table.
  7. Predentary ventral process broad, expanding in width toward its proximal end.
  8. Dentary teeth with a bulbous, cone-shaped primary ridge occupying approximately one third of the crown face, with secondary ridging.

Species (9)

Psittacosaurus mongoliensis Osborn, 1923

Type species

From mongoliensis ("of Mongolia"), referring to the country of origin of the holotype.

Holotype
AMNH 6254 , American Museum of Natural History
Material
Nearly complete adult skull and jaws plus articulated partial postcranial skeleton (vertebrae, most of the limb elements).
Horizon
Cannonball Member, Öösh Formation, Berriasian–Albian, Early Cretaceous , 143.1–100.5 million years ago
Locality
Red Mesa, Övörkhangai, Mongolia

Synonyms

  • Protiguanodon mongoliense junior subjective

    Erected by Osborn (1923) in the same paper as Psittacosaurus mongoliensis on AMNH 6253 from the Ondai Sair Formation; synonymized with P. mongoliensis by Sereno (1990) after reexamination of both type skeletons, and confirmed in Sereno (2010).

  • Psittacosaurus guyangensis junior subjective

    Sereno (1990) found all distinguishing characteristics fall within the growth series of P. mongoliensis; tentatively reaffirmed by Sereno (2010).

  • Psittacosaurus osborni junior subjective

    Sereno (1990) found the distinguishing characters (small size, tooth-ridge morphology) fall within the growth series of P. mongoliensis. Sereno (2010) reaffirmed the synonymy as tentative pending more material.

  • Psittacosaurus tingi junior subjective

    Treated by Young (1958) as a junior synonym of P. osborni, and by Sereno (1990) as indistinguishable from P. mongoliensis. Sereno (2010) lists it in the synonymy of P. mongoliensis while also regarding it as a nomen dubium, its holotype being two small dentaries.

Psittacosaurus sinensis Young, 1958

From Latin 'sinensis' meaning 'of China', for the country of origin.

Holotype
IVPP V738 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Articulated adult skeleton with a nearly complete skull, missing only the palpebrals and the tip of the left jugal horn; postcranium missing distal forelimb elements, carpus, manus, distal tarsals, and some phalanges.
Horizon
Doushan Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Doushan village, 5 km northwest of Laiyang, Shandong, China
Diagnosis
  1. Pendant rostrum with the ventral edge of the rostral bone positioned below the level of the maxillary tooth row.
  2. Anteroventral processes of the nasal separated at the midline by a narrow gap.
  3. Short lower jaw positioning the anterior margin of the predentary in opposition to the premaxilla rather than the rostral.
  4. Posteriorly flaring skull roof with postorbital-squamosal bars diverging at an angle of approximately 30 degrees.
  5. Vertically elongate horn on the postorbital bar, split between the jugal and postorbital, unlike the arched postorbital crest of P. mongoliensis.
  6. Frontal participates in the supratemporal fossa, and the internal mandibular fenestra is reduced to a foramen.

Synonyms

  • Psittacosaurus youngi junior subjective

    Based on a partial skeleton and well-preserved skull (BNHM BPV149) from the same beds and localities as the P. sinensis holotype; its diagnosis included no autapomorphies distinguishing it. Sereno (1990) found it indistinguishable from P. sinensis, to which it is now referred.

Psittacosaurus xinjiangensis Sereno & Chao, 1988

Refers to Xinjiang Uygur Autonomous Region, China, where the holotype was found

Holotype
IVPP V7698 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
posterior portion of the skull including the jugal horn and palpebral, and an articulated skeleton lacking distal limb bones and tail
Horizon
Tugulu Group, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
Delunshan, Junggar Basin, Xinjiang, China
Diagnosis
  1. Hook-shaped palpebral with a V-shaped posterior margin
  2. Dentary teeth with as many as 21 denticles in the posterior center of the tooth row
  3. Ossified tendons extending into the mid-caudal vertebrae, absent in other psittacosaur species
  4. Narrow iliac postacetabular process with height at midlength less than 25% of the process length, versus 30% or more in P. mongoliensis, P. major, P. sinensis, and P. sibiricus
  5. Small occipital condyle with transverse width less than half the width of the basal tubera, versus more than half in other species

Psittacosaurus meileyingensis Sereno et al., 1988

Named for the Meileyingzi locality near Beipiao, Liaoning Province, where the type material was found.

Holotype
IVPP V7705 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Skull with jaws, lacking the jugal horns and central body of the premaxilla.
Horizon
Meileyingzi Bed, Jiufotang Formation, Aptian–Albian, Early Cretaceous , 121.4–100.5 million years ago
Locality
Meileyingzi, Liaoning, China
Diagnosis
  1. Preorbital skull length only about 30% of total skull length, versus roughly 37% in P. mongoliensis.
  2. Subtriangular orbit with an acute ventral corner.
  3. Rugose quadratojugal eminence, unlike the smooth eminence present in most other species including P. mongoliensis.
  4. Ridge ascending from the maxillary protuberance, a feature shared only with P. major.
  5. Strong, pendant dentary flange, unlike the low flange in P. mongoliensis.
  6. Small external mandibular fenestra.

Psittacosaurus neimongoliensis Russell & Zhao, 1996

Named for Nei Mongol (Inner Mongolia), the autonomous region of China where the holotype was found

Holotype
IVPP 12-0888-2 , Institute of Vertebrate Paleontology and Paleoanthropology
Material
Articulated skeleton with skull
Horizon
Ejinhoro Formation, Aptian–Albian, Early Cretaceous , 121.4–100.5 million years ago
Locality
1 km southeast of Yangpo village, 80 km west of Dongsheng, Inner Mongolia, China
Diagnosis
  1. Skull large relative to trunk, unlike in P. mongoliensis
  2. Preorbital portion of skull less than 35% of skull length, versus about 37% in P. mongoliensis
  3. Prefrontal lacks the raised lateral (orbital) edge present in P. mongoliensis
  4. External mandibular fenestra closed, unlike the open fenestra in P. mongoliensis
  5. Distal end of ischial blade not transversely broadened, unlike the expanded ischial blade of P. mongoliensis
  6. Anterior process of squamosal stops short of the body of the postorbital

Psittacosaurus lujiatunensis Zhou et al., 2006

Named for the Lujiatun locality/beds (lowermost Yixian Formation), Liaoning Province, China, where the type material was collected.

Holotype
ZMNH M8137 , Zhejiang Museum of Natural History
Material
skull with lower jaws
Horizon
lower Lujiatun Member, Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
Lujiatun, near Beipiao, Liaoning, China
Diagnosis
  1. Prefrontal width less than 50% that of the nasal (an autapomorphy)
  2. Quadratojugal contacts the squamosal along the anterior margin of the quadrate shaft, unlike the separated condition in P. mongoliensis
  3. Jugal contacts the quadrate posteroventral to the laterotemporal fenestra, unlike the separated condition in P. mongoliensis
  4. Bears a prominent, pendant dentary flange with a squared anterior corner, unlike the low flange in P. mongoliensis
  5. External mandibular fenestra closed, unlike the retained open fenestra in P. mongoliensis

Psittacosaurus gobiensis Sereno et al., 2010

Gobi, after the Gobi Desert; -ensis (Latin) belonging to.

Holotype
LH PV2 , Long Hao Institute of Geology and Palaeontology
Material
Skull and articulated postcranial skeleton with gastrolith mass, lacking only portions of the right manus, some of the sacrum and pelvic girdle, and the right hind limb and tail.
Horizon
Bayin-Gobi Formation, Aptian, Early Cretaceous , 121.4–113.2 million years ago
Locality
southwest of Suhongtu, Inner Mongolia, China
Diagnosis
  1. Pyramidal postorbital horn formed almost entirely by the postorbital, unlike the primitive postorbital shape and ornamentation of P. mongoliensis
  2. Retroarticular process deflected posteromedially about 40 degrees from the mandible axis, versus the straight retroarticular process in P. mongoliensis
  3. Shorter, deeper skull proportions than the longer-snouted P. mongoliensis, with lower tooth count (8 maxillary, 9 dentary teeth)
  4. Many cranial and mandibular sutures fused despite maturity, whereas P. mongoliensis retains open sutures despite comparable size
  5. Postorbital-jugal fossa present, and minimum width of the postorbital bar about 50 percent the width of the process base
  6. Thin, restricted enamel on medial maxillary and lateral dentary crowns respectively, an asymmetry emphasized more than in other species

Psittacosaurus amitabha Napoli et al., 2019

Named for Amitabha, the Buddha of infinite light, associated with extreme longevity; principal Buddha of Pure Land Buddhism, highly venerated in Mongolia.

Holotype
IGM 100/1132 , Paleontological Center, Mongolian Academy of Sciences
Material
Nearly complete, undistorted skull with associated partial mandible and fragmentary postcranial elements (ribs, forelimb fragment, pes, 21 caudal vertebrae, gastroliths).
Horizon
Andakhuduk Formation, Barremian–Aptian, Early Cretaceous , 125.8–113.2 million years ago
Locality
Ondai Sayr, Ussuk, Övörkhangai, Mongolia
Diagnosis
  1. Snout relatively longer than in P. mongoliensis, with a less steeply inclined anterior rostronasal margin.
  2. Cranium dorsally convex rather than flat, unlike the flattened skull roof seen in other Psittacosaurus.
  3. Subtemporal length less than 40% of total skull length.
  4. Five premaxillary foramina arranged in an arc, more numerous than in any other known Psittacosaurus species.
  5. Posterior lamina of the maxilla cupped around the toothrow, contrasting with P. mongoliensis where the tooth-bearing pedestal contacts the pterygoid without a cupped lamina.
  6. Antorbital fossa as long as it is tall.
  7. Palpebral with a well-developed posterior tongue-like process extending over half the orbit length, unlike the subtriangular palpebral of other Psittacosaurus.

Psittacosaurus sibiricus Leshchinskiy et al., 2000

Named for Siberia, the region of Russia where the holotype was found.

Holotype
PM TGU 16/4-20 , Paleontological Museum, Tomsk State University
Material
An articulated, almost complete adult skeleton including the skull.
Horizon
Ilek Formation, Aptian–Albian, Early Cretaceous , 121.4–100.5 million years ago
Locality
Shestakovo 3, Chebula District, Kemerovo, Russia
Diagnosis
  1. Skull width exceeds skull length, unlike the proportionately narrower skull of P. mongoliensis.
  2. Infratemporal fenestra small, its maximum height only 25% of skull length versus 31-38% in P. mongoliensis and other congeners.
  3. Premaxilla anteroposteriorly short, with a maximum length-to-height ratio under 60%, unlike the longer premaxilla of P. mongoliensis.
  4. Postorbital bears a short medial process that does not contribute to the orbital margin, unlike the condition in P. mongoliensis.
  5. Jugal has a deep cleft for the quadratojugal that extends onto the posterior face of the jugal horn, unlike P. mongoliensis.
  6. Angular bears a prominent tuber and there are 23 presacral vertebrae, both differing from the condition in P. mongoliensis.

Synonyms of the genus

Name Type Reason
Hongshanosaurus houi junior subjective Erected by You and colleagues (2003) on an immature, dorsoventrally crushed skull from the Yixian Formation; the genus was sunk into Psittacosaurus by Sereno (2010), who treated the species itself as a nomen dubium (too crushed and immature to diagnose) and suggested that the referred adult skull likely pertains to P. lujiatunensis. The name therefore attaches to the genus rather than to any one species.

References

  1. Osborn, H. F. (1923). Two Lower Cretaceous dinosaurs of Mongolia. American Museum Novitates 95: 1-10.

    Erects Psittacosaurus mongoliensis on AMNH 6254 (Ashile Formation); also names Protiguanodon mongoliense on AMNH 6253 (Ondai Sair Formation), of comparable size to the holotype.

    osborn1923b
  2. Sereno, P. C. (1990). New data on parrot-beaked dinosaurs (Psittacosaurus). Dinosaur Systematics: Perspectives and Approaches (Carpenter, K.; Currie, P. J., eds.) 203-210. Cambridge University Press, Cambridge. doi:10.1017/CBO9780511608377.018

    Modern revision establishing the generic diagnosis; formally synonymizes Protiguanodon and several Young/Cheng species into P. mongoliensis or P. sinensis.

    sereno1990a
  3. Sereno, P. C. (2010). Taxonomy, cranial morphology, and relationships of parrot-beaked dinosaurs (Ceratopsia: Psittacosaurus). New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium (Ryan, M. J.; Chinnery-Allgeier, B. J.; Eberth, D. A., eds.) 21-58. Indiana University Press, Bloomington.

    Comprehensive modern review of the genus; recognizes nine valid species and sinks Hongshanosaurus into Psittacosaurus.

    sereno2010a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026a
  5. Young, C. C. (1958). The dinosaurian remains of Laiyang, Shantung. Palaeontologia Sinica, New Series C, Whole Number 142(16): 1-138.

    Erects Psittacosaurus sinensis (Laiyang, Shandong); also treated P. tingi as a junior synonym.

    young1958a
  6. Sereno, P. C.; Chao, S. (1988). Psittacosaurus xinjiangensis (Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northwestern China. Journal of Vertebrate Paleontology 8(4): 353-365. Informa UK Limited. doi:10.1080/02724634.1988.10011724

    Erects Psittacosaurus xinjiangensis on holotype IVPP V7698 from the Tugulu Group of Xinjiang.

    sereno1988a
  7. Sereno, P. C.; Chao, S.; Cheng, Z.; Rao, C. (1988). Psittacosaurus meileyingensis (Ornithischia: Ceratopsia), a new psittacosaur from the Lower Cretaceous of northeastern China. Journal of Vertebrate Paleontology 8(4): 366-377. Informa UK Limited. doi:10.1080/02724634.1988.10011725

    Erects Psittacosaurus meileyingensis on holotype IVPP V7705 from the Jiufotang Formation of Liaoning.

    sereno1988b
  8. Russell, D. A.; Zhao, X. J. (1996). New psittacosaur occurrences in Inner Mongolia. Canadian Journal of Earth Sciences 33(4): 637-648. Canadian Science Publishing. doi:10.1139/e96-047

    Erects Psittacosaurus neimongoliensis on holotype IVPP 12-0888-2 from the Ejinhoro Formation of Nei Mongol.

    russell1996a
  9. Zhou, C. F.; Gao, K. Q.; Fox, R. C.; Chen, S. H. (2006). A new species of Psittacosaurus (Dinosauria: Ceratopsia) from the Early Cretaceous Yixian Formation of Liaoning, China. Palaeoworld 15(1): 100-114. Elsevier BV. doi:10.1016/j.palwor.2005.11.001

    Erects Psittacosaurus lujiatunensis on holotype ZMNH M8137 from the Lujiatun beds (lowermost Yixian Formation) of Liaoning.

    zhou2006b
  10. Sereno, P. C.; Zhao, X.; Tan, L. (2010). A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull. Proceedings of the Royal Society B: Biological Sciences 277(1679): 199-209. The Royal Society. doi:10.1098/rspb.2009.0691

    Erects Psittacosaurus gobiensis on holotype LH PV2 from the Bayan Gobi Formation of Nei Mongol.

    sereno2010b
  11. Napoli, J. G.; Hunt, T.; Erickson, G. M.; Norell, M. A. (2019). Psittacosaurus amitabha, a new species of ceratopsian dinosaur from the Ondai Sayr Locality, Central Mongolia. American Museum Novitates 3932: 1-36. American Museum of Natural History. doi:10.1206/3932.1

    Erects Psittacosaurus amitabha on holotype IGM 100/1132 from the Andakhuduk Formation of central Mongolia.

    napoli2019a
  12. Leshchinskiy, S. V.; Fayngertz, A. V.; Voronkevich, A. V.; Maschenko, E. N.; Averianov, A. O. (2000). Preliminary results of the investigation of the Shestakovo localities of Early Cretaceous vertebrates. Materials of the Regional Conference of the Geologists of Siberia, Far East and North East of Russia 363-366. GalaPress.

    Paper in which the name Psittacosaurus sibiricus first validly appeared; the species is credited within it to Voronkevich and Averianov.

    leshchinskiy2000a
  13. Averianov, A. O.; Voronkevich, A. V.; Leshchinskiy, S. V.; Fayngertz, A. V. (2006). A ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of West Siberia. Journal of Systematic Palaeontology 4(4): 359-395. Informa UK Limited. doi:10.1017/S1477201906001933

    Full redescription of Psittacosaurus sibiricus on holotype PM TGU 16/4-20 from the Ilek Formation (Shestakovo) of West Siberia.

    averianov2006a
  14. Andres, B.; Norell, M. A. (2005). The first record of a pterosaur from the Early Cretaceous strata of Öösh (Övörkhangai; Mongolia). American Museum Novitates 3472: 1-6.

    Places the Psittacosaurus mongoliensis holotype in the cannonball beds at the base of the Öösh Formation, and gives Övörkhangai for the locality.

    andres2005a
  15. Rougier, G. W.; Novacek, M. J.; McKenna, M. C.; Wible, J. R. (2001). Gobiconodonts from the Early Cretaceous of Oshih (Ashile), Mongolia. American Museum Novitates 3348: 1-30.

    Ranks the Cannonball a member of the Öösh Formation and traces the locality's naming from Osborn's Ashile through the Oshih of Berkey and Morris.

    rougier2001a
  16. You, H.; Xu, X.; Wang, X. (2003). A new genus of Psittacosauridae (Dinosauria: Ornithopoda) and the origin and early evolution of marginocephalian dinosaurs. Acta Geologica Sinica (English Edition) 77(1): 15-20. doi:10.1111/j.1755-6724.2003.tb00105.x you2003e
  17. Zhong, Y.; Huyskens, M. H.; Yin, Q. Z.; Wang, Y.; Ma, Q.; Xu, Y. G. (2021). High-precision geochronological constraints on the duration of 'Dinosaur Pompeii' and the Yixian Formation. National Science Review 8(6): nwab063. doi:10.1093/nsr/nwab063

    Dates the base of the Yixian Formation, the Lujiatun Unit that yielded P. lujiatunensis, to 125.755 Ma: Barremian on the ICS chart v2024/12 at its central value; its error reaches the Hauterivian.

    zhong2021a
  18. Gale, A. S.; Mutterlose, J.; Batenburg, S.; Gradstein, F. M.; Agterberg, F. P.; Ogg, J. G.; Petrizzo, M. R. (2020). The Cretaceous Period. Geologic Time Scale 2020 (Gradstein, F. M.; Ogg, J. G.; Schmitz, M. D.; Ogg, G. M., eds) 1023-1086. Elsevier, Amsterdam. doi:10.1016/B978-0-12-824360-2.00027-9

    Gives the GTS2020 Barremian span, 126.5 to 121.4 Ma; the ICS chart v2024/12 starts the stage at 125.77 Ma.

    gale2020a
  19. Hedrick, B. P.; Dodson, P. (2013). Lujiatun psittacosaurids: understanding individual and taphonomic variation using 3D geometric morphometrics. PLoS ONE 8(8): e69265. doi:10.1371/journal.pone.0069265

    Sinks P. major and Hongshanosaurus houi into P. lujiatunensis on 3D geometric morphometrics of the Lujiatun skulls.

    hedrick2013a
  20. Ishikawa, A.; Zheng, W.; Imai, T.; Hattori, S.; Shibata, M.; Kawabe, S.; Jin, X. (2025). Psittacosaurus houi, a longer snouted psittacosaurid from the Lower Cretaceous Lujiatun Unit of Yixian Formation, China, with the synonymy of the unresolved genus Hongshanosaurus revisited. PeerJ 13: e19547. PeerJ. doi:10.7717/peerj.19547

    Treats P. houi as a valid species of Psittacosaurus on a new skull, ZMNH M12414, and keeps P. major apart from P. lujiatunensis in its tree.

    ishikawa2025a