An ancient platypus turned out to be toothy

The species in question is Obdurodon insignis, an ancient toothy duck-billed platypus from the late Oligocene. Its fossils were found at Billeroo Creek in South Australia, east of the Flinders Ranges. The new finds include a lower molar, upper premolar and part of a humerus bone.

Details

The modern platypus loses its teeth shortly after hatching. Adult animals chew their food with horn plates rather than teeth. The ancient Obdurodon insignis, on the other hand, retained its teeth and was well developed.

According to the researchers, large and strong teeth could help the animal to split the prey with a shell or hard exoskeleton - for example, crayfish and other aquatic invertebrates.

Another important find was part of a bone that supported a forelimb. It showed that the ancient platypus was well adapted to swimming and resembled the modern platypus in the structure of its forelimbs.

Why it matters

Platypus fossils are extremely rare, so even a few new bones can significantly refine their evolutionary history. Obdurodon insignis was previously known from very limited fragments, and the new finds help us better understand how it fed and moved.

In addition, the find shows that 25 million years ago there were already animals in Australia that were very similar to today's platypuses in lifestyle, but with an important difference - they were toothy and probably a little larger.

The backcountry

Back then, central Australia looked very different. Where there are now arid areas, there were permanent lakes, slow-moving rivers and wooded lowlands. This ecosystem was home to ancient double-breathing fish, waterfowl, flamingos and small freshwater dolphins.

This is not to say that the modern platypus is directly descended from Obdurodon insignis. It is more correct to say that it is its ancient relative, which helps reconstruct the broader history of one of the most unusual mammalian lineages.

Source

The study by Trevor H. Worthy, Gen A. Conway and Aaron B. Camens published in Australian Zoologist in 2026: New material of the toothed platypus Obdurodon insignis from the late Oligocene Pinpa Local Fauna at Billeroo Creek, South Australia.