Litokoala

{{Short description|Extinct genus of marsupials}} {{Automatic taxobox | fossil_range = {{fossilrange|16|10}} | image = Litokoala.JPG | image_caption = Artist's reconstruction | taxon = Litokoala | authority = [[Ruben Arthur Stirton|Stirton]], [[Tedford]] & [[Michael O. Woodburne |Woodburne]], 1967.<ref name="Stirton1967">{{cite journal |last1=Stirton |first1=R. A. |last2=Tedford |first2=Richard H. |last3=Woodburne |first3=Michael O. |title=A new Tertiary formation and fauna from the Tirari Desert, South Australia |journal=Records of the South Australian Museum |date=1967 |volume=15 |issue=3 |pages=427–462 |url=https://www.biodiversitylibrary.org/part/262888}}</ref> | subdivision_ranks = Species | subdivision = *'''''L. dicktedfordi'''''<ref name=Pledge2010>N. S. Pledge. 2010. A new koala (Marsupialia : Phascolarctidae) from the late Oligocene Etadunna Formation, Lake Eyre Basin, South Australia. ''Australian Mammalogy'' 32:79-86.</ref> Pledge, 2010 *'''''L. garyjohnstoni'''''<ref>Louys, J., K. Black, M. Archer, S. J. Hand, and H. Godthelp. 2007. Descriptions of koala fossils from the Miocene of Riversleigh, northwestern Queensland and implications for ''Litokoala''. ''Alcheringa'' 31:99–110.</ref> Louys ''et al.'', 2007 *'''''L. kutjamarpensis'''''<ref name="Stirton1967" /> ([[type species]]) Stirton ''et al.'', 1967 *'''''L. kanunkaensis''''' Springer, 1987 *'''''L. thurmerae'''''<ref name=Pledge2010/> Pledge, 2010 *'''''L. dicksmithi'''''<ref>[[Karen H. Black]], Julien Louys & Gilbert J. Price (2013). «Understanding morphological variation in the extant koala as a framework for identification of species boundaries in extinct koalas (Phascolarctidae; Marsupialia)». Journal of Systematic Palaeontology (published 14 May 2013) doi:10.1080/14772019.2013.768304</ref>Black, Louys & Price 2013 }}

'''''Litokoala''''' is an [[extinct]] [[genus]] of [[marsupial]]s, 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 around 16–10 million years ago in the middle Miocene [[Australian Fossil Mammal Sites (Riversleigh)|Riversleigh]] of [[Queensland]]. This area is described as a rainforest habitat at time of sediment [[Deposition (geology)|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 basio[[:wikt:occipital|occipital]]-basi[[Sphenoid bone|sphenoid]] flexion and a more extensive posterior attachment of the [[Pterygoid bone|pterygoid]]",<ref>(Louys et al., 2009, p. 989)</ref> 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.

== References == {{Reflist}}

[[Category:Miocene mammals of Australia]] [[Category:Prehistoric vombatiforms]] [[Category:Miocene marsupials]] [[Category:Koalas]] [[Category:Prehistoric marsupial genera]] [[Category:Riversleigh fauna]] [[Category:Fossil taxa described in 1967]]