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Dryad

Data from: New fossil koala (Marsupialia: Phascolarctidae) from the Pleistocene of Western Australia

Travouillon, Kenny1; Warburton, Natalie2; Thorn, Kailah1; Ryan, Helen1

Research facility: Western Australian Museum
Published Apr 27, 2026 on Dryad. https://doi.org/10.5061/dryad.9zw3r22vg

Data files

Apr 27, 2026 version files 26.04 MB

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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.