However, there have been fossil relatives of the platypus, belonging to the same family. These include:
* Obdurodon: A genus of extinct platypus that lived in Australia from the Oligocene to the Pleistocene epochs, about 23 million to 11,700 years ago. They were larger than the modern platypus and had different tooth structures.
* Steropodon: A genus of even older extinct platypuses that lived during the early Paleocene epoch, around 66 million years ago. They were smaller than modern platypuses and had more primitive features.
So, while the modern platypus is unique in its own right, there are extinct relatives that provide insight into the evolution of this fascinating creature.