Photo: Hany Mahmoud
The pig-nosed turtle, an endangered freshwater turtle native to the Northern Territory and southern New Guinea, is unique in many respects.
Unlike most freshwater turtles, it’s almost completely adapted to life in water. It has paddle-like flippers similar to sea turtles, a snorkel-like “pig-nose” to help it breathe while staying submerged, and eggs that will only hatch when exposed to the waters of the wet season.
It’s also the last surviving species of a group of tropical turtles called the carettochelyids, which once lived throughout the northern hemisphere. Scientists thought pig-nosed turtles only arrived at Australia within the past few millennia, as no pig-nosed turtle fossils had ever been found here – or so we thought.
A five-million-year-old fossil from Museums Victoria’s collections has now completely rewritten this story. Discovered at Beaumaris, 20km southeast of Melbourne, this fossil lay unidentified in Melbourne Museum’s collection for almost 100 years until our team came across it.
We identified the fossil as a small section of the front of a pig-nosed turtle’s shell, as we report this week in the journal Papers in Palaeontology. Although the fossil is just a fragment, we were lucky it was from a very diagnostic area of the shell.
The five-million-year-old pig-nosed turtle fossil, in life position on the shell of a modern pig-nosed turtle. Photo: Erich Fitzgerald
The fossil shows that carettochelyid turtles have been living in Australia for millions of years. But what was a pig-nosed turtle doing in Beaumaris five million years ago, thousands of kilometres from their modern range?
Well, in the past, Melbourne’s weather was a lot warmer and wetter that it is now. It was more akin to the tropical conditions in which these turtles live today.
In fact, this isn’t the first prehistoric tropical species discovered here – monk seals, which today live in Hawaii and the Mediterranean, and dugongs also once lived in what is now Beaumaris.
Source : lens.monash.edu
