Researchers from the University of New South Wales have discovered fossils of a bizarre, previously unknown family of ancient carnivorous Australian marsupials. The new family lived approximately 15 million years ago and fed on snails.
"Malleodectes mirabilis was a bizarre mammal, as strange in its own way as a koala or kangaroo," said Mike Archer of the UNSW and lead author of the study. "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."
Although Archer and his team have been excavating isolated teeth and partial dentitions of the unique family for years, it took the discovery of a well-preserved portion of a juvenile skull originating from the Middle Miocene epoch for the team to realize just how different these unique marsupials were.
The specimen was recently extracted from limestone casing from the Riversleigh World Heritage Fossil Site in northwestern Queensland using an acid bath and examined using modern techniques such as micro-computed tomography.
"Details of the canine, premolar and molar teeth of this specimen have enabled its relationships to other Australian marsupials to be determined with reasonable confidence," Archer said. "Although it is very different from the others, it appears to have been related to the dasyures - marsupial carnivores such as Tasmanian Devils and the extinct Tasmanian Tigers that are unique to Australia and New Guinea."
The limestone case originated from the floor of the Riversleigh cave, which contains thousands of bones from the animals that inhabited the ancient cave millions of years ago. These fossils paint a picture of the animals, including M. mirabilis, and how they lived.
"The juvenile malleodectid could have been clinging to the back of its mother while she was hunting for snails in the rocks around the cave's entrance, and may have fallen in and then been unable to climb back out," said Suzanne Hand of UNSW and co-author of the study.
"Many other animals that lived in this lush forest met a similar fate with their skeletons accumulating one on top of another for perhaps thousands of years, until the cave became filled with palaeontological treasures," she added.
The findings were published in the May 27 issue of the journal Scientific Reports.
