Newly Discovered Extinct Koala Relative Found in Western Australia

Australia’s unique wildlife once included a second species of koala, endemic to Western Australia, which became extinct approximately 30,000 years ago.

The sole surviving species, Phascolarctus cinereus, thrives primarily in the eucalypt forests of eastern Australia. Unfortunately, they face threats including habitat destruction, disease outbreaks, vehicular collisions, and predation by invasive species.

Over the last century, fossils of koalas dating from 137,000 to 31,000 years ago have been unearthed in Western Australian caves. However, researchers lacked sufficient material to determine distinct species classifications until recently.

In the past 25 years, more fossils have been discovered, including a well-preserved skull donated by the family of the late speleologist, Lindsay Hatcher, who explored numerous caves in southwest Western Australia.

“The donation included a koala skull in excellent condition,” reveals Kenny Travouillon from the Western Australian Museum. “Upon examining the skull, we noted some differences from modern koalas, prompting further research into our fossil collection.”

To the untrained observer, the new species, named Phascolarctus sulcomaxiliaris, may appear similar to P. cinereus, but they exhibit notable differences.

“Essentially, the Western Australian koalas were similar yet distinct,” Travouillon explains. “Their heads were shorter and had less developed masticatory muscles compared to their eastern counterparts, indicating a different chewing mechanism, characterized by larger teeth and shorter jaws suited for efficiently processing leaves.”

The pronounced grooves on the cheeks of P. sulcomaxiliaris suggest the presence of robust muscles for maneuvering large lips to grasp leaves or to enhance their sense of smell from a distance. Additionally, its skeleton appears less agile, implying it was not as adept at navigating through trees.

About 30,000 years ago, as the climate dried and forests in Western Australia diminished, P. sulcomaxiliaris became extinct alongside many other species that shared this habitat, including the Tasmanian devil, sugar glider, echidna, short-faced kangaroo, and the giant marsupial Zygomaturus.”

“The first human inhabitants of Western Australia would have coexisted with these fascinating creatures, witnessing their extinction,” notes Tim Flannery of the Australian Museum in Sydney. “This research provides compelling evidence that the Western Australian koala represents a unique species. We hope to extract DNA from these fossils in the future.”

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