A procolophonid reptile from the Lower Triassic of Australia

Abstract

Abstract A new procolophonid reptile from the Lower Triassic Arcadia Formation of Queensland, Australia is described on the basis of abundant cranial and postcranial remains. Eomurruna yurrgensis gen. & sp. nov. is the first parareptile from Australia, being represented by more than 40 specimens from which a detailed description of the osteology is made. The most characteristic feature of Eo. yurrgensis is the presence of six to eight blunted, monocuspid maxillary teeth that are circular in basal cross-section. The new Australian taxon features an interdigitated tooth-occlusion system that represents an intermediate functional stage between the primitive procolophonoid pattern, without apparent tooth-to-tooth contact, and the crown-to-crown occlusion system characteristic of the horned procolophonids. Its dentition suggests good capabilities of oral processing and shows instances of replacement. A phylogenetic analysis suggests that the new taxon occupies a relatively basal position within the Procolophonidae. The taxonomic status of the procolophonoid species ‘Owenetta’ kitchingorum and Saurodektes rogersorum from South Africa and ‘Eumetabolodon’ dongshengensis from China is reassessed. The new genus Youngetta gen. nov. and the new combinations Saurodektes kitchingorumcomb. nov. and Youngetta dongshengensiscomb. nov. are here proposed.