The South African stereospondyl Microposaurus from the Middle Triassic of the Sydney Basin, Australia

ABSTRACT

The second member of the Trematosaurinae (Temnospondyli, Stereospondyli) from Australia is described as Microposaurus averyi, n. sp., from the Anisian Rouse Hill Siltstone (Ashfield Shale, Wianamatta Group, Sydney Basin). This is the first occurrence of the genus from outside South Africa. M. averyi and the South African M. casei share an anterior emargination of the nostril that accommodated the dentary fangs (a condition unique among temnospondyls), but the emargination is much larger in the Australian taxon. The Anisian stereospondyls from the Sydney Basin occur in sediments younger than the early Anisian and may fill a worldwide gap in terrestrial tetrapod faunas from that time.

ACKNOWLEDGMENTS

I thank S. Avery for drawing AM F.135895 to the attention of The Australian Museum, Sydney, for donating it to their collections, and for stratigraphic and photographic help, A. Ritchie for drawing it to my attention, R. Jones and Yong Yi, for loan of the specimen, R. Damiani for lengthy discussions, R. Helby for stratigraphic discussion, and G. Grigg for crocodile information. The paper was improved after reviews by A. Yates and S. Steyer, and editing by J. Anderson.

Handling editor: Jason Anderson.