In 2024, the Western Australian Museum received a donation. It was a koala skull collected from Moondyne Cave in Margaret River by Lindsay Hatcher, an avid caver. There was something a bit odd about this skull, and we were able to put our finger in it. This koala had dimples. Koalas are iconic on Australia’s east coast, but they are regionally extinct in Western Australia today. Fossils tell a different story: koalas once lived across parts of WA, from the Margaret River region to as far north as Yanchep and as far east as Madura. In our new study, published today in Royal Society Open Science, we show these WA koalas were not simply stray populations of the modern koala. They represent a distinct species that has been hiding in plain sight for more than a century. Not like the koalas we know Koala fossils in WA were first discovered in Mammoth Cave near Margaret River in 1910. But for the better part of a century, most specimens consisted of isolated jaws and teeth.…