No animal alive today looks quite like a duck-billed platypus, a semi-aquatic, egg-laying mammal hailing from eastern Australia. But about 250 million years ago, something very similar swam the shallow seas in what is now China, finding prey by touch with a cartilaginous bill. The newly discovered marine reptile Eretmorhipis carrolldongi from the lower Triassic period is described in the journal Scientific Reports Jan. 24.
What drives species to move into such a different habitat? Two paleontologists at UC Davis, Geerat Vermeij and Ryosuke Motani, set out to test these ideas by compiling a list of all the groups of mammals, birds, reptiles and amphibians that have re-occupied marine environments and comparing their time of return to the ocean with known mass-extinction events.