Nothosaurs were fierce semi-aquatic predators that hunted along the ocean coasts of the world-continent of Pangea during the Triassic period 251 million to199 million years ago. The fossils of these ancient reptiles show that they had flat elongated fore and hind limbs and debate has raged for years on whether they flew through the water like penguins or rowed with their paddle-shaped appendages. Tracks found recently in China have solved the mystery.
The tracks were discovered on a ledge in China’s Yunnan province by Qi-yue Zhang, a member of the Chengdu Center of the China Geological Survey. His team uncovered 350 prints forming 15 different trackways. They photographed and scanned the tracks using airborne lidar (laser and radar sensors) and compared them to the numerous fossils found in this area that was heavily populated with sea creatures in the Triassic age.
The comparisons ruled out reptiles with separated toes or digits on their limbs, those that were too small for the large paddles and those that were unable to stand on the limbs underwater without dragging their bellies across the seabed. By this process of elimination, Michael Benton, a paleontologist at the University of Bristol in England, positively identified the tracks as belonging to the 13-foot-long Nothosaurus and the 2-foot-long Lariosaurus, both nothosaurs.
The shape of the tracks prove that the nothosaurs rowed through the water using their front limbs as paddles and as props to keep their bellies off the bottom. Professor Zhang describes and interprets the findings in the current Nature Communications.
We interpret the tracks as foraging trails. The nothosaur was a predator, and this was a smart way to feed. As its paddles scooped out the soft mud, they probably disturbed fishes and shrimps, which it snapped up with needle-sharp teeth.
Here’s my question: to pass the time while paddling, did the nothosaurs sing ‘Row, row, row your butt’?