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.