New material of enantiornithine birds from the Early Cretaceous of Australia

Abstract

Remains of tiny enantiomithines from the Early Cretaceous (Albian) of Queensland, Australia, include a proximal tibiotarsus and a cervical vertebra consistent in size with Nanantius eos (Molnar 1986). The new tibiotarsus differs in detail from the type and so probably does not pertain to the same species. The vertebra is platycoelous with a tendency toward opisthocoely. It shows that Enantiomithes had distinctive process of vertebral development, different from that in true birds which produces heterocoelous vertebrae. The excellent preservation of the vertebra permits the accurate orientation of fragmentary vertebrae in some Enantiomithes known from other continents. It also corroborates both the existence of Enantiomithines in the Early Cretaceous of Australia and the small size of the genus Nanantius.