A system of tooth wear and replacement is postulated for the Triassic ornithischian dinosaur Fabrosaums. This scheme is based upon the evidence of worn tooth crowns. Tooth replacement is of the normal reptilian type described by Edmund (1960). Tooth wear is unlike that in most ornithischian dinosaurs (being matched only in the late Cretaceous Thescelosaurus) and involves the development of two wear surfaces one ach crown. This peculiar wear pattern necessitates interlocking of the upper teeth with the lower during occlusion and indicates an essentially vertical jaw action. The muscular basis for such a jaw action is briefly considered.