A hippo-sized marsupial with downward-curving tusks that wallowed in swamps across Australia. It went extinct around 40,000 years ago, shortly after humans arrived. The timing suggests hunting or habitat burning may have doomed this gentle giant.
Paleocolour, CC0, via Wikimedia Commons
The Yoked-Cheek Beast
Zygomaturus trilobus was a powerhouse of the Pleistocene epoch. This giant marsupial stood about 1.5 meters tall and 2.5 meters long, with a heavy build similar to a modern pygmy hippopotamus. Its weight is estimated to have been 500 kilograms or more. As a member of the extinct family Diprotodontidae, its closest living relatives are wombats and koalas.
The animal’s name, Zygomaturus, means "big cheekbones," referring to the massive, flaring zygomatic arches of its skull. These powerful bone structures anchored strong jaw muscles. The skull also featured widely flared nasal bones and raised nostrils, adaptations for a semi-aquatic lifestyle. Some paleontologists think the unusual bone structure at the front of the skull may have supported small horns or a mobile, pig-like snout for rooting up plants. Like modern wombats, Zygomaturus had a backward-facing pouch, which would have kept its young from drowning while the mother foraged in swamps.
A Swampy Demise
Fossil evidence shows Zygomaturus preferred the wet, coastal margins and forested regions of Australia, following river systems inland. It was a browser, and its diet likely consisted of soft vegetation like reeds and sedges, which it could have scooped up with its lower incisor teeth. Other analyses of its low-crowned, broad teeth suggest it could also crush tougher material like stems, bark, and roots.
The genus Zygomaturus first appeared in the Miocene epoch, around 8 million years ago. The last known species, Z. trilobus, vanished during the Late Pleistocene. For many years, the extinction was dated to around 45,000 years ago, placing it close to the time of human arrival on the continent. More recent dating of fossils from the Willandra Lakes Region in New South Wales suggests it may have survived until 33,000 to 37,000 years ago. This overlap has led to the hypothesis that human activity, such as hunting or landscape burning, contributed to its extinction. However, other research points to significant climate change during this period as a cause for the disappearance of Australia's megafauna.
💡Fun Facts
The name *Zygomaturus* is Greek for "yoked cheekbones," describing its massive, arching cheekbones.
Its closest living relatives are the wombat and the koala.
The skull's structure suggests it may have had a three-lobed nose or even a short trunk.
Like a wombat, its pouch faced backward, which would have protected its young from mud and water while it foraged.
The fossil-bearing regions of New South Wales are not a formal site with opening hours. To see curated skeletons, visit the Australian Museum in Sydney or the Queen Victoria Museum in Launceston.
Admission
Visiting the general region is free. Museum admission fees apply.
Accessibility
Fossil sites are often in remote and rugged terrain, requiring private transport and hiking. Museums are generally fully accessible.
