Scientists discovered that Australia had been home to a hitherto-unknown, extinct species of marsupial whose diet consisted chiefly of snails.

The discovery at the Riversleigh World Heritage Fossil Site in Queensland, Australia, is the fossil of a mammal, subsequently named Malleodectes mirabilis. This site is a cave deposited with limestone, which has become an important collection of fossils after years of accumulating fallen animals in its pit.

The research was headed by Mike Archer, who is a palaeontologist and professor at the University of New South Wales. According to the Scientific Reports journal, where the scientists have published their study, Malleodectes's dental structure points to its preferred food to have been snails, although it is likely to have fed on small vertebrates as well. Archer said in a statement to the press that its most interesting feature was a huge, hammer-like premolar tooth that was likely used to crack the shells of snails.

The fossil that triggered the finding belonged to a young Malleodectes whose skull and teeth had been preserved well enough for the scientists to glean information about its age, diet and near relatives. It was found with its baby teeth intact, along with a set of adult teeth underneath them. The remains were found in the cave estimated to be around 15 million years old, so it is believed that the marsupial species belonged to that time period.

Marsupials are mammals that have many peculiar features, one of which is that most species carry their young ones in pouches attached to the mother's abdomen. Commonly known marsupials are kangaroos and koalas. The newly discovered species of marsupials have been found to be carnivores, related to other carnivorous marsupials like the Tasmanian Devil.

The scientists speculate that Malleodectes became extinct due to the inability to adapt to the climate change in Australia, which gradually caused its rainforests to give way to grasslands and sparse vegetation, thereby their food source dried up as the land did.