A newly discovered koala species, Phascolarctos maxillaris, once roamed Western Australia, differing significantly from its eastern relatives. Image Credit: Wikipedia
Over the past century, it seemed that the Australian Koala’s story was straightforward. They were the fluffy, eucalyptus-eating icons of eastern states. A recent discovery made in Western Australia completely changed the story. While the koalas we know today thrived on the eastern side of Australia, their secret relative lived a completely different existence in the forests and caves of western Australia.The Western Australian Museum was the first to receive this donation. The story of a koala’s skull that was originally discovered in Moondyne Cave by caver Lindsay Hatcher waited to be told. Researchers noticed something strange when they finally looked closer. This specimen had deep, round dimples on the cheeks. This was the “thumbprint’ of an animal that scientists had ignored for over 100 years.New species hidden in plain viewExperts assumed for a very long time that the koala fossils discovered in Western Australia were just members of the current species, Phascolarctos Cinereus. This was an obvious guess given the similarity of many marsupial fossils to a non-trained eye. A team of researchers decided to test this assumption using comparative anatomy.These results were published in the Royal Society Open Science journal and show that they are not our familiar koalas. Researchers officially named the new species Phascolarctos maxillaris. Named after its most distinguishing characteristic, “sulco”, which means groove and “maxillaris”, which refers to the cheekbone.The prehistoric West Australian was not just an “embellished” cousin of the eastern counterpart. This species has a smaller, stronger skull with broader teeth. While its skull was more robust, the limbs were thinner and longer. The slender and agile body shape is compared with the stockier, rounder koalas that we see in today’s sanctuaries.
This prehistoric marsupial, identified by unique cheekbone grooves, possessed a more robust skull and slender build. Image Credit: Wikipedia
Face mattersIt might seem strange that a small groove on a cheekbone would be so important. Form always follows function in the field of biology. The cheek is the area where the muscles that control the nose and lips attach in koalas. Researchers believe that the Phascolarctos has more powerful and larger facial muscles because of its deep grooves.The ancient WA Koala would now have possessed a more flexible upper lip. Imagine the precision with which a koala could manipulate leaves and select shoots on a tree using its lips, snout or snout. The extra dexterity, combined with the enhanced smell that could be attributed to the greater movement of the nostrils, suggests an expert who was tuned into the environment in the Margaret River ancient region.Warning from the pastThe research team returned to its source to understand the fate of this rare creature. The team trekked through the narrow, dusty passages in Koala Cave at Yanchep as well as Foundation Cave near Margaret River. They were able to pinpoint the exact date of disappearance by using radiocarbon and uranium-thorium dating.It is likely that the “dimpled koala” went extinct around 28,000 years. The significance of this date lies in the fact that it coincides with an era when Australia’s climate was drastically drier and colder. Ancient pollen records show that the south-west’s lush eucalyptus forest shrank dramatically during this period.Koalas have a reputation for being fussy eaters. The forests are part of their biology. The WA Koala was left with nowhere to live when the trees vanished. The discovery of this koala is a reminder to all how vulnerable these animals can be when their habitats are lost. As we confront modern climate changes and deforestation today, Phascolarctos’ story serves as an historical blueprint of what happens to a specialist species when its habitat is lost.The research adds another koala to Australia’s family tree, but it also shows that Australia once had a wider range of koalas. The history of the koala is richer than anyone could have imagined. From the Pleistocene “giant koala” that was two times the size of the modern-sized critters to the slender and dimpled West Coast specialised koala, this iconic animal’s past has been far more complex.
