Psittacosaurus

Lore & Background

In 1922, American paleontologist Henry Fairfield Osborn took part in the Third Asiatic Expedition of the American Museum of Natural History to Mongolia. In the Oshih Formation of the Artsa Bogdo mountain range, the Mongolian chauffeur Wong discovered a nearly complete skull, jaws, and skeleton of a dinosaur. Osborn described the specimen in 1924, naming it Psittacosaurus mongoliensis for its parrot-like beak, on the suggestion of fellow paleontologist William King Gregory. Osborn also described another taxon, Protiguanodon mongoliense, from the same expedition but a different formation; Gregory suggested it might be a juvenile of Psittacosaurus, a view later supported by further preparation and study.

Following discoveries in Inner Mongolia, Yang Zhongjian described two additional species in 1932: Psittacosaurus osborni and P. tingi. Soviet expeditions from 1946 to 1949 uncovered more material, and Soviet paleontologist Anatoly Rozhdestvensky in 1955 proposed that Protiguanodon mongoliense, P. osborni, and P. tingi were junior synonyms of P. mongoliensis. In 1958, Yang described a new species, Psittacosaurus sinensis, from Shandong, and revised classifications, retaining some earlier species while making Protiguanodon a junior synonym under the new name Psittacosaurus protiguanodonensis. Further discoveries led to the naming of Psittacosaurus youngi in 1962 by Zhao Xijin.

Reader's Guide

Psittacosaurus is one of the most completely known dinosaur genera, with fossils of hundreds of individuals collected, including many complete skeletons representing most age classes from hatchling through adult. This abundance has allowed detailed studies of growth rates and reproductive biology. The genus is so common in Lower Cretaceous sediments of east Asia that those sediments are labeled the Psittacosaurus biochron. One individual was preserved with long filaments on the tail, similar to those of Tianyulong. Psittacosaurus probably had complex behaviors based on brain proportions and size, may have been active for short periods during day and night, and had well-developed senses of smell and vision. The first species was either P. lujiatunensis or closely related, and it may have given rise to later forms. The genera closely related to Psittacosaurus are all from Asia, with the exception of Aquilops from North America.

Did You Know?

• Psittacosaurus is the most species-rich non-avian dinosaur genus, with up to 13 known species.
• One individual was preserved with long filaments on the tail, similar to those of Tianyulong.
• The first specimen was discovered in 1922 by a Mongolian chauffeur named Wong during the Third Asiatic Expedition.
• Psittacosaurus was once placed in its own family Psittacosauridae, but is now considered an early offshoot of the branch leading to more derived ceratopsians.