New Prehistoric Marine Reptile Resembled a Miniature Mix of Loch Ness Monster, Alligator and Toothy T. Rex

The researchers originally thought the fossils belonged to the well-known nothosaurs, but analysis revealed an entirely new species

Two photos of the two fossils are next to each other. The fossils show the skeletal imprints of the two newly discovered reptiles in gray stone.
Qing-Hua Shang, Xiao-Chun Wu and Chun Li / Journal of Vertebrate Paleontology Qing-Hua Shang, Xiao-Chun Wu and Chun Li / Journal of Vertebrate Paleontology

About 240 million years ago, massive oceanic reptiles called nothosaurs dominated the seas. They looked like the mutant offspring of a trihybrid cross between the Loch Ness monster, an alligator and a T. rex. The beasts had long tails to slither underwater, jaws packed with razor-sharp teeth and flipper-like limbs to propel themselves through the water.

When a team of paleontologists from the Chinese Academy of Scientists and Canadian Museum of Nature discovered two small, similar fossils in quarries in southwest China, the scientists originally thought they belonged to juvenile nothosaurs. Further analysis revealed that they actually discovered a new species—the nothosaur's smaller, stockier cousin. The team's findings were published last week in the Journal of Vertebrate Paleontology, reports Science News' Aayushi Pratap.

The team named the newly unearthed reptile Brevicaudosaurus jiyangshanensis, which roughly means "short-tailed lizard of Jiyangshan," the quarry it was found in, according to the press release.

Large nothosaurs could exceed 16 feet in length, but scientists estimate that B. jiyangshanensis adults only reached about 1.5 to 2 feet. The fossils also had rounder, more well-defined bones, indicative of an adult, reports Science News. Compared to bigger nothosaurs, this species had a shorter, flatter tail and denser bones.

"A long tail can be used to flick through the water, generating thrust, but the new species we've identified was probably better suited to hanging out near the bottom in shallow sea, using its short, flattened tail for balance, like an underwater float, allowing it to preserve energy while searching for prey," Qing-Hua Shang, a researcher at the Chinese Academy of Sciences in Beijing, says in the press release.

The anatomy of the fossils helped scientists zero in on how B. jiyangshanensis likely behaved. It had dense bones, which helped it stay neutrally buoyant in the water column, and a broad tail to stay balanced. Plus, an expanded rib cage suggests that the reptile also had large lungs, allowing them to stay underwater for longer, reports Science Focus.

Because it was shorter and stockier, it certainly wasn't as agile as its larger, leaner cousin. But instead of speed, B. jiyangshanensis could likely "walk on the seabed" in search of slow-moving critters to feast on.

"This is the first discovery of a small-sized species of a big-sized group," Xiao-Chun Wu, a paleobiologist at the Canadian Museum of Nature in Ottawa, Canada, tells Science News. "This is a very new lifestyle we now know about nothosaurs."