Psittacosaurus(redirected from Psittacosaurus sinensis)
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a genus of extinct Early Cretaceous reptiles of the order Ornithischia. The animals measured 1–1.5 m in length and were marked by bipedal locomotion. Their taxonomic position is debatable: the shape of their skull resembles that of Ceratopsia, their teeth resemble those of Ankylosauria, and the structure of the limbs resembles that of Ornithopoda. Psittacosaurus most probably represent a branch of the Stegosauria—Ankylosauria that retained bipedal locomotion. The small, serrate teeth apparently made it possible to gnaw and grind hard plants. The hooflike phalanges are evidence of adaptation to walking on muddy ground. The reptiles evidently lived along shores in thickets, where it was easy to find food and hide from enemies.