Meet a newly discovered family of snail-chomping carnivorous Australian marsupials

Reconstruction of Malleodectes chomping down on what appears to have been its favourite food — snails. Illustration by Peter Schouten.

The remains of a bizarre snail-eating Australian carnivorous marsupial have been uncovered in Queensland.

The previously unknown extinct marsupials lived 15 million years ago, grew to about half the size of a cat and appear to be related to the dasyures, the marsupial carnivores such as Tasmanian devils and the extinct Tasmanian tiger.

“Malleodectes mirabilis was a bizarre mammal, as strange in its own way as a koala or kangaroo,” says study lead author Mike Archer at the University of NSW.

“Uniquely among mammals, it appears to have had an insatiable appetite for escargot — snails in the whole shell. Its most striking feature was a huge, extremely powerful, hammer-like premolar that would have been able to crack and then crush the strongest snail shells in the forest.”

The ferret-sized marsupials were found in an area which has been producing regular amazing finds.

These include a tusked kangaroo called Fangaroo, strange leopard-like crocodiles called Drop crocs which may have been lived in trees, and Dromornis, the Demon Duck of Doom, which was one of the largest birds in the world.

Research describing the marsupials is published in the journal Scientific Reports.

Isolated teeth had been unearthed over the years at Riversleigh World Heritage Fossil Site in north-western Queensland where Professor Archer and his colleagues have excavated for almost four decades.

But the different nature of the marsupials was not realised until a well-preserved portion of the skull of a juvenile was found in a 15-million-year-old Middle Miocene cave deposit.

Maxilla of the young malleodectid from the fossil cave. Images: Karen Black and Suzanne Hand.

This juvenile was only recently extracted from its limestone casing, using an acid bath at UNSW, which made it available for study with modern techniques including micro-computed tomography.

Nothing remains of the cave at Riversleigh, except its limestone floor, which contains the bones of thousands of animals that fell into, or lived in, the ancient cave.

Many other animals that lived in this lush forest met a similar fate with their skeletons accumulating one on top of another for thousands of years.

The Riversleigh World Heritage fossil deposits span the last 24 million years of Australian history.

The Riversleigh Project, which has been a major focus of the palaeontological team at UNSW, is about to carry out its 40th annual expedition to Riversleigh.

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