Litokoala
Litokoala is an extinct genus of marsupials, and along with "Nimiokoala", is closely related to the modern koala. The three genera may have diverged at an earlier date, although the drying of the continent and the expansion of "Eucalyptus" forests towards the late Miocene may have delayed the evolution of cranial features unique to the modern genera. This indicates that either fossil genus could be an ancestor of the modern genus, or the modern genus has a common ancestor to both. More material needs collection to improve their taxonomical relationships. The genus lived about 10–16 million years ago in  the middle Miocene Riversleigh of Queensland. This area is described as a rainforest habitat at time of sediment deposition. It had a different diet to the modern species, with the dental symphysis unfused, indicating a diet that was properly varied in nature, unlike the specialised nature of "Phascolarctos". The size is estimated to be only half of the modern genus. Cranial adaptations are intermediate between the extant common brushtail possum and koala, with minor divergence from either. This genus and "Nimiokoala" are similar in most anatomical features so far as is known, except "Litokoala" possessed a superficial messateric process, while  Nimiokoala had "more marked basiooccipital-basisphenoid flexion and a more extensive posterior attachment of the pterygoid", which make these features basal in their taxonomical position in relation to the "Phascolarctos". The basiocranial (back of skull) features are similar to "Phascolarctos", while anterior (facial) features exhibit similarities with the genus "Trichosurus". Only partial fragments are known, with only the posterior section of the zygomatic process known from the "L. kutjamarpensis" skull.