There are three species of wombats alive today, all perfectly adapted to Australia’s rough wilderness. Some 25 million years ago, however, the continent was roamed by a giant wombat-like marsupial, which was only recently described by scientists.

The animal was more than four times the size of any living wombats today and had some unique features deserving of its own new family of marsupials.

The newly identified ancient mammal is called Mukupirna – meaning “big bones” in the Dieri and Malyangapa Aboriginal languages.

The extinct giant creature was now described based on a partial skull and almost complete skeleton originally discovered in 1973 in the clay floor of Lake Pinpa — a remote, dry salt lake east of the Flinders Ranges in South Australia.

Mike Archer, co-author of the new study and a professor at the University of New South Wales (UNSW), was part of the team that performed the original fieldwork in the 1970s.

Like many amazing paleontological discoveries before them, Archer recounts how they came across the fossils by accident, after a fortunate change in atmospheric conditions revealed the 25 million-year-old fossil deposits on the floor of the dry lake.

“It was an extremely serendipitous discovery because in most years the surface of this dry lake is covered by sands blown or washed in from the surrounding hills,” he says.

“But because of rare environmental conditions prior to our arrival that year, the fossil-rich clay deposits were fully exposed to view. And this unexpected view was breathtaking.”

Besides the remains of Mukupirna, the paleontologists also collected a wealth of fossils belonging to other extinct ancient creatures.

“On the surface, and just below we found skulls, teeth, bones and in some cases, articulated skeletons of many new and exotic kinds of mammals. As well, there were the teeth of extinct lungfish, skeletons of bony fish and the bones of many kinds of water birds including flamingos and ducks.

“These animals ranged from tiny carnivorous marsupials about the size of a mouse right up to Mukupirna which was similar in size to a living black bear. It was an amazingly rich fossil deposit full of extinct animals that we’d never seen before.”

It took almost 50 years to properly describe Mukupirna since its fossils had been solidly encased in clay for all this time. It was only recently that Archer and collegues revisited the fossils, finding that the clay pristinely preserved the remains of a new marsupial family.

A gentle giant

Judging from its skeleton, the paleontologists estimate that Mukupirna was a very powerful beast the size of a black bear today — more than four times the size of any living wombats, weighing about 150 kilograms.

Mukupirna likely foraged in an open forest environment, where it used its powerful teeth to feed on sedges, roots, and tubers, which it would have dug out with its muscular front legs.

Given its voluminous size, Mukupirna sits on the top end of vombatiform marsupials — the taxonomic group that includes Mukupirna, as well as modern wombats, koalas, and their fossil relatives.

“Koalas and wombats are amazing animals,” Dr. Robin Beck from the University of Salford in the UK said in a statement, “but animals like Mukupirna show that their extinct relatives were even more extraordinary and many of them were giants.”