Lengthy-overlooked fossils in the Western Australian Museum assortment were known as a brand new species of koala. Named Phascolarctos sulcomaxilliaris, the traditional animal disappeared from Western Australia as drought and chilly reshaped its habitat on the finish of the Pleistocene.

The modern koala (Phascolarctos cinereus) is Australia’s greatest extant arboreal folivore and one of probably the most iconic Australian marsupials.

Koalas happen in a wide range of woodland varieties at the east coast of Australia and feature been translocated to a number of spaces of South Australia close to Adelaide and on Kangaroo Island.

The species is listed as Susceptible through the IUCN and has suffered inhabitants declines traditionally via land clearing, illness, automobile strike, canine and attempting to find the fur business.

“Koalas are locally extinct in Western Australia (WA), however their fossils were recognized since 1910,” mentioned Dr. Kenny Travouillon, a researcher on the Western Australian Museum and Curtin College, and associates.

“Bones had been prior to now reported from a number of cave deposits in the south-west of WA, Koala Cave in Yanchep and from Madura Cave at the Roe Simple.”

“Because of the similarity of the dentition with Phascolarctos cinereus, they had been historically assumed to be the similar species.”

Of their find out about, the paleontologists tested 98 bones from fossil specimens in the Western Australian Museum assortment.

They when compared skulls, enamel and postcranial bones with trendy koala skeletons from museum collections on Australia’s east coast.

The effects confirmed transparent and quantifiable variations between the WA fossils and their japanese family members, confirming the presence of a brand new species, named Phascolarctos sulcomaxilliaris.

“The species differs from trendy koalas in a number of putting tactics,” Dr. Travouillon mentioned.

“Deep grooves in the cheekbone housed a big facial muscle, suggesting the animal will have had strangely massive, cell lips, most likely for manipulating eucalyptus leaves, or possibly to flare its nostrils to support its sense of scent and locate meals from larger distances.”

“Its skeleton was once most probably much less agile than trendy koalas and will have spent much less time transferring between bushes.”

Phascolarctos sulcomaxilliaris’ fossils have now been known from greater than a dozen cave deposits throughout southern Western Australia, together with websites in Yanchep, Margaret River and the Roe Simple close to Madura.

This well-liked distribution displays that those koalas as soon as occupied a a ways broader vary than prior to now recognised.

Radiometric courting signifies that Phascolarctos sulcomaxilliaris disappeared round 28,000 years in the past.

“This timing aligns with a big Past due‑Pleistocene local weather tournament all the way through which eucalyptus forests gotten smaller to round 5% of their present extent,” Dr. Travouillon mentioned.

“With meals and safe haven dramatically lowered, koalas in the area most probably confronted critical habitat loss, resulting in the extinction of this distinctive species.”

A paper describing Phascolarctos sulcomaxilliaris was once revealed these days in the magazine Royal Society Open Science.

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Kenny Travouillon et al. 2026. New fossil koala (Marsupialia: Phascolarctidae) from the Pleistocene of Western Australia. R Soc Open Sci 13 (5): 251572; doi: 10.1098/rsos.251572