Original paper

Buccal soft anatomy in Lesothosaurus (Dinosauria: Ornithischia)

Knoll, Fabien


The probable buccal soft anatomy of the basal ornithopod Lesothosaurus, from the Early Jurassic of southern Africa, is appraised. A labial emargination does not establish the existence of a malar structure because such a configuration is present in a number of extant lizards, but generally absent in mammals. Judging from the condition in lizards, the pattern of labial foramination is not reliable evidence of the presence of cheeks either. The perioral hard anatomy of Lesothosaurus does not offer any conclusive support for the presence of cheeks or mammalian style lips. Lesothosaurus very probably bore both an upper and a lower horny beak of very limited caudal extent, based on the vascularized and roughened surface texture of the rostral extremities of the jaws.