The plant-eating mammal called Mukupirna nambensis, known from the fossil of a partial skull and much of the skeleton unearthed at Lake Pinpa in northeastern South Australia state, is one of the earliest-known large-bodied Australian marsupials, they said.
Mukupirna, meaning “big bones” in the local Aboriginal language, provides insight into the evolution of a marsupial group called vombatiforms that includes koalas and wombats. It was a cousin of wombats – distinctive muscular and short-legged animals – and boasts skeletal traits showing the beginnings of certain wombat features such as adaptations for digging, though probably was unable to burrow like a wombat.
Australia was dominated not by placental mammals – cats, dogs, elephants, apes, horses and others – as most continents were after the demise of the dinosaurs 66 million years ago but by marsupials, mammals that give birth to immature young to be carried and suckled in a pouch on the mother’s belly.
Mukupirna weighed about 330 pounds (150 kg), similar to an American black bear and five times bigger that modern wombats.
“It may have looked a bit wombat-like, but with a smaller head, longer, less robust limbs and a longer tail. It probably fed on roots and tubers, which it could have dug up with its powerful forelimbs,” said Robin Beck, who led the research published in the journal Scientific Reports.
“It is a very unusual animal, related to wombats but with its own unique features that led us to classify it in its own family,” Beck added.