| Litokoala | |
|---|---|
 | |
| Artist's reconstruction | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Diprotodontia |
| Family: | Phascolarctidae |
| Genus: | †Litokoala Stirton,Tedford &Woodburne, 1967.[1] |
| Species | |
Litokoala is anextinctgenus ofmarsupials, and along withNimiokoala, is closely related to the modernkoala. The three genera may have diverged at an earlier date, although the drying of the continent and the expansion ofEucalyptus 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 around 16–10 million years ago in the middle MioceneRiversleigh ofQueensland. This area is described as a rainforest habitat at time of sedimentdeposition. It had a different diet to the modern species, with the dentalsymphysis unfused, indicating a diet that was properly varied in nature, unlike the specialised nature ofPhascolarctos. The size is estimated to be only half of the modern genus. Cranial adaptations are intermediate between the extantcommon brushtail possum and koala, with minor divergence from either.
This genus andNimiokoala are similar in most anatomical features so far as is known, exceptLitokoala possessed a superficialmessateric process, whileNimiokoala had "more marked basiooccipital-basisphenoid flexion and a more extensive posterior attachment of thepterygoid",[5] which make these features basal in their taxonomical position in relation to thePhascolarctos. The basiocranial (back of skull) features are similar toPhascolarctos, while anterior (facial) features exhibit similarities with the genusTrichosurus. Only partial fragments are known, with only the posterior section of thezygomatic process known from theL. kutjamarpensis skull.
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