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89
107
, W. P. J. 1982. Juvenile specimens of the ornithischian dinosaur Psittacosaurus. Palaeontology, 25, 1, 89–107.
W. P. Coombs Jr. Hitherto undescribed specimens of Psittacosaurus mongoliensis from the Oshih Fm., Mongolian Peoples' Republic, include two almost complete skulls and numerous postcranial elements. A rostral bone, present in these and other specimens of Psittacosaurus, is a cranial element otherwise known only in ceratopsians, and its presence indicates a sister group relationship for the Psittacosauridae and Ceratopsia. Each of the two new specimens of Psittacosaurus is a juvenile, and are among the smallest dinosaur specimens yet described. Parental attendance of nests was common, possibly universal among dinosaurs, but post-hatching parental care is uncertain. Juveniles of Psittacosaurus, as well as those of other dinosaurs, may have formed sibling groups. The Palaeontological Association (Free Access)