The Ilariidae are a family of three species of extinct marsupials in two genera. They are all found in the middle Tertiary assemblage of South Australia, and are closely related to the family Phascolarctidae, which was found in Hamilton, Victoria. I. illumidens is the best-preserved representative of this extinct clade of vombatiforms. The species is found in the Namba Formation of late Oligocene age, Lake Pinpa, South Australia. The material consists of a partial cranium and mandibular fragments with most of the dentition, together with parts of the postcranial skeleton. The other species in this family are known from a few jaw fragments and intact molars attached; they are categorised in a separate family because their teeth structure is unique among Diprotodontia, in having a complicate