A giant wombat the size of a black bear that roamed Australia 25 million years ago has been classified as a new category of marsupial after almost 50 years of study.
The bones of Mukupirna nambensis were unearthed in the clay floor of Lake Pinpa, a remote, dry salt lake east of South Australia’s Flinders Ranges in 1973.
An international team of scientists from various institutions. including the University of NSW and Griffith University, have been studying the remains.
A partial skull and most of the skeleton belonged to animal more than four times the size of modern living wombats and may have weighed about 150kg.
“An analysis of Mukupirna’s evolutionary relationships reveals that although it was most closely related to wombats, it is so different from all known wombats as well as other marsupials, that it had to be placed in its own unique family, the Mukupirnidae,” the researchers said.
UNSW Professor Mike Archer is a co-author of a paper on the creature published on Friday in Scientific Reports.
He is part of the original international team of palaeontologists that discovered the remains in the clay floor of Lake Pinpa.
47 years in the making, we can now introduce to the world Mukupirna nambensis, a 25 million year old, bear sized (150 kg) #marsupial related to #wombats – #OA paper in @SciReports https://t.co/DX7xDmzwb4 – reconstruction by the brilliant Peter Schouten @SalfordUni @SalfordScience pic.twitter.com/xhFwfqGfD6
— Robin Beck (@robinmdbeck) June 25, 2020
The discovery of Mukupirna was in part due to good luck, after an unusual change in local conditions exposed the 25 million-year-old fossil deposit on the floor of the 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,” Prof Archer said.
“But because of rare environmental conditions prior to our arrival that year, the fossil-rich clay deposits were fully exposed to view.
“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.”
Prof Archer says when Mukupirna’s skeleton was first discovered, just below the surface, nobody had any idea what kind of animal it was because it was encased in clay.
The team discovered it by “probing the dry flat surface of the Lake with a thin metal pole, like acupuncturing the skin of Mother Earth” to reveal “the articulated skeleton of a most mysterious new creature”.
The researchers’ recent study of the partial skull and skeleton reveals that despite its bear-like size, Mukupirna was probably a gentle giant that subsisted only on plants, but was unlikely to have been a burrower like modern wombats.
Researchers from UNSW, Griffith University, Salford University in the UK, the Natural History Museum in London, and the American Museum of Natural History in New York took part in the study.