Researchers have always thought there was only one species of the unique platypus alive at a time, but evidence of a giant beast that once walked the Earth may have changed their minds.
A single tooth found in Queensland is what led researchers to believe the creature, dubbed Obdurodon tharalkooschild, existed, a Society of Vertebrate Paleontology reported.
"Monotremes (platypuses and echidnas) are the last remnant of an ancient radiation of mammals unique to the southern continents. A new platypus species, even one that is highly incomplete, is a very important aid in developing understanding about these fascinating mammals," PhD candidate Rebecca Pian, lead author of the study, said.
The tooth suggests the creature was three feet long, which is twice the of today's species.
"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," Doctor Suzanne Hand of the University of New South Wales, a co-author of the study, said. "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."
The oldest-known platypus lived in South America 61-million years ago. The platypus fossil record suggests the animals grew smaller and had a reduced tooth size over time.
"Discovery of this new species was a shock to us because prior to this, the fossil record suggested that the evolutionary tree of platypuses was relatively linear one," said Dr. Michael Archer of the University of New South Wales, a co-author of the study. "Now we realize that there were unanticipated side branches on this tree, some of which became gigantic."
