Described as a hybrid of a wombat and a marsupial lion, the beast named Mukupirna fortidentat a is thought to have weighed up to 50 kg.
The skull, bone and jaw fragments of the animal were found in an area near Alice Springs in central Australia.
The researchers say the finding sheds light on how modern-day marsupials evolved.
A team from Flinders University worked over 2,000 hours to extract 35 different samples of Mukupirna from hard limestone.
These helped paint a picture of what the animal would look like.
According to researcher Arthur Crichton, the creature resembles a marsupial lion, which it shares in common with modern-day wombats and is also known as Thylacoleo carnifex.
“They are a kind of evolutionary intermediate between wombats and their more koala-like relatives,” he told the BBC.