Queensland's 24 million-year-old Riversleigh World Heritage fossil deposits have proffered some stupefying discoveries of extinct animals over the years.

There's been the 'fangaroo', a tusked kangaroo; tree-climbing crocodiles known as 'drop crocs', and the enormous 'demon duck of doom'.

An artist's impression of a Malleodectid crushing a snail in its teeth. Credit:Peter Schouten

Now we can add to that list of oddities a marsupial that feasted on snails.

Christened Malleodectides - or "wondrous hammer biter" - the furry creature was about the size of a ferret and had massive premolars (the teeth between incisors and molars) made for crunching and digesting whole snails.