The largest platypus fossil ever found – or, rather its tooth, the largest fossilized platypus molar – was just unearthed in Australia. Analysis of the platypus fossil suggests the creature, a new species of platypus, was twice the size of modern monotremes.

According to, researchers from the University of New South Wales identified the new species, called Obdurodon tharalkooschild, after coming across a single molar that belonged to the animal. They unearthed the platypus molar while digging in the Riversleigh World Heritage Area of northwest Queensland, a desert region that was covered in forest millions of years ago. They believe the fossil is between 5 million and 15 million years old.

"Suddenly up pops 'platypus-zilla' - this gigantic monstrosity that you would have been afraid to swim with,” Mike Archer, a professor at the University of New South Wales, told the BBC. "It indicates there are branches in the platypus family tree that we hadn't suspected before."

According to NBC News, measurements of the molar allowed scientists to estimate the size of the “platypus-zilla.” They believe the animal was about 3.3 feet long – twice the size of platypuses today. The bumps and ridges on the prehistoric platypus molar also indicate what the creature would have eaten.

"Like other platypuses, it was probably a mostly aquatic mammal, and would have lived in and around the freshwater pools in the forests that covered the Riversleigh area millions of years ago," Dr. Suzanne Hand of the University of New South Wales, a co-author of the study, said in a statement. "Obdurodon tharalkooschild was a very large platypus with well-developed teeth, and we think it probably fed not only on crayfish and other freshwater crustaceans, but also on small vertebrates including the lungfish, frogs and small turtles that are preserved with it in the Two Tree Site fossil deposit."

According to Science Daily, the oldest platypus fossils come from 61 million-year-old rocks in southern South America. The discovery of Obdurodon tharalkooschild suggests that descendants of the prehistoric platypus became smaller over time.

Australia seems ripe for discoveries of prehistoric fossils these days. Just last month, researchers uncovered the oldest bird footprints in Australia. The footprints, found in slab of sandstone recovered from the cliffs of Dinosaur Cove, were more than 100 million years old.