Abstract
Fossils of koalas have been known from Western Australia since 1910, but are today regionally extinct. Jaws and bones were previously reported from several cave deposits in the south-west of WA, Koala Cave in Yanchep, and from Madura Cave on the Roe Plain. Due to the similarity of the dentition with the east coast koalas (Phascolarctos cinereus), they were traditionally assumed to be the same species. Two complete additional adult skulls were collected in the past 25 years. These skulls are interpreted to belong to a male and female koala, are similar in body size to koalas from Victoria, but the shape of the skulls differ significantly, in being relatively much shorter in length, and having obvious deep concavities on the maxilla, below the zygomatic arch. Differences from the eastern species are also apparent in the postcranial skeleton. Analysis of measurements on the skulls and teeth show that the Western Australian koala is morphologically distinct from its east coast relative and warrants consideration as its own species. It likely went extinct in WA as a result of climate change during the late Pleistocene, which reduced eucalyptus forests to around 5% of their current cover, reducing resources for food and shelter.
Description of the data and file structure
Data has been collected and collated for the description of the anatomy of the new fossil taxon Phascolarctos sulcomaxilliaris, alongside efforts to date the age of the fossils, and place the new taxon into a phylogeny.