Strange hammerlike teeth seen in two newfound species of ancient marsupials -- teeth unknown in any other mammal -- were the weapons they once used to smash open snail shells.

Oddly, a bizarre group of lizards alive today in the rain forests of eastern Australia possess extraordinarily similar teeth, and their ancestors might have driven those snail-eating marsupials to extinction struggling over their sluggish prey. [Image of fossil marsupial]

The fossil marsupials, discovered in semi-arid northern Australia, are 10 million to 17 million years old, and lived back when the area was a temperate lowland forest. The ferret-sized species are named Malleodectes mirabilis and Malleodectes moenia -- Latin and Greek for "extraordinary hammer-biter" and "fortified hammer-biter," respectively.

These creatures each had enormous premolars, which in humans would be located between the canines and molars. The specimen they first investigated "appeared so odd that initially none of the team could work out exactly what it was," researcher Rick Arena, a paleontologist at the University of New South Wales in Australia, told LiveScience. "The teeth were unlike any we had ever seen before in a mammal, so we were scratching our heads."