New paddle prints uncovered in China reveal how predatory reptiles that inhabited the oceans during the age of the dinosaurs used a rowing motion to scoop up their prey.
The newly uncovered tracks are from creatures known as nothosaurs, the top predators of the oceans during the Triassic period, which lasted from 251 million to 199 million years ago. The findings put an end to a long-standing debate about how the ancient sea creatures swam, said study co-author Michael Benton, a paleontologist at the University of Bristol in England.
The paddle prints were detailed Wednesday in the journal Nature Communications.
Nothosaurs were definitely strange-looking marine reptiles that swam about the Triassic oceans about 245 million years ago. The marine predators had paddlelike forelimbs and hind limbs, long necks and tails, and long jails complete with small, pointy teeth, Brenton said.
Qi-yue Zhang, a member of the Chengdu Center of the China Geological Survey, was mapping geological features of China’s Yunnan province, which is known for its array of spectacular fossilized sea creatures, when he noticed several paddle prints on a ledge. The team dug up the area on the ledge and found 350 exquisitely preserved prints that formed about 15 different trackways, some of which looped around, Brenton said.
The researchers then used photos and an airborne laser scanning called lidar to map the tracks.
The team then compared the tracks with fossils from other animals that lived during the same time period in that region of the world. The comparison ruled out other reptiles whose separated digits would have left imprints, as well as smaller creatures or those that lacked the ability to touch the seabed with their front limbs without dragging their bellies on the bottom as well, Benton told Live Science.
That led to the conclusion of nothosaurs, with both the large Nothosaurus, which could reach 13 feet in length, and the scrappy, 2-foot long Lariosaurus as the likely culprits.
After analyzing the tracks, the team deduced that the nothosaurs may have rowed their front limbs into the seabed, floating their bellies above so they didn’t touch the seafloor. The rowing motion would have churned up lobsters and fish that took shelter in the soupy sediment just along the seabed, Benton said.
“By punting along like this, the nothosaur flushed these edible morsels out and snapped them up,” Benton said.
The new discovery provides more information on the ecosystems of about 8 million years after the end-Permian extinction, also known as the Great Dying, when about 96 percent of marine species and 70 percent of terrestrial animals died, Benton said.
Paddle Prints Uncover How Predatory Reptiles Moved During Triassic Period