Giant Platypus!

The animals and plants of the Oligocene rainforest at Riversleigh (as envisioned by an artist)

Occasionally in the geological past, extraordinary circumstances resulted in the near-perfect preservation of an entire ecosystem.  These astonishing fossil beds are known as Lagerstätten (one of the first such finds was in Germany) and they provide one of the best sources of information about life on this planet.  A particularly rich Lagerstätten is located in the arid scrubland of Riversleigh in northwest Queensland, Australia: there fossils from the Oligocene and Miocene epochs are preserved in uncompressed limestone (which allows paleontologists to recover 3 dimensional skeletal remains).  During the late Oligocene, Riversleigh was a lush and vibrant rainforest filled with an incredible profusion of bizarre life forms.  When the Oligocene ended, the region dried into grasslands (and the climate continued to dry out further in subsequent epochs until the present, when the area is a near desert).

The giant carnivorous platypus (Obdurodon tharalkooschild)

All of this is backstory to a remarkable recent discovery.  This week paleontologists studying the bats, snakes, and strange tropical marsupials of Riversleigh made an unexpected discovery–a giant hunting platypus twice the size of the living species.  This big predator, Obdurodon tharalkooschild, was a formidable meter long (3 foot) creature with sharp teeth for grabbing crayfish, amphibians, aquatic reptiles, and fish.  The newly discovered platypus lived in the long-lost rainforests of Queensland.  It was a generalist with a much larger diet than the somewhat specialized modern platypus.

No, it wasn’t THAT big…

Monotremes (platypuses & the more recently evolved echidnas) are an extremely ancient branch of mammalian life which date back at least to the Jurassic–and more likely to the Triassic epoch or earlier.  Platypuses are believed to have evolved in what is now South America and then spread to Antarctica and finally to Australia.  The amazing giant hunting platypus indicates that there were hitherto unexpected branches of platypus evolution. I wonder if  Obdurodon tharalkooschild was toxic (like the modern platypus).  I also wonder what strange monotreme fossils lie beneath the ancient ice of Antarctica.