A newly discovered species of amphibian called Gerrothorax maritimus was about 74 centimeters long and had a flattened, armored body. Credit: Ryosuke Motani Amphibians could live in the sea 237 million years ago, according to research published today in Nature Ecology & Evolution. Two fossils of a type of early amphibian from a group called temnospondyls were found in what is now Guizhou province in China, which would have been a salt sea. during the Late Triassic period. Researchers have tentatively named the species Gerrothorax maritimus. The creatures, 74 centimeters long, had flattened bodies and were almost completely covered in armor. There are more than 8,000 species of modern amphibians, but none of them live exclusively in a marine environment. “This is a potentially revolutionary discovery,” says Steve Brusatte, a paleontologist and evolutionary biologist at the University of Edinburgh, UK. “If this Triassic amphibian, Gerrothorax, really was completely marine, then it’s a game-changer.” Schematic of one of the amphibian fossils, color-coded according to the parts of the skeleton and with bones labeled. Credit: Diao, L. et al./Nature Ecol. Evol. Amphibians have different levels of salt tolerance, says Ryosuke Motani, a paleobiologist at the University of California, Davis, and co-author of the study. But even salt-tolerant animals need to recover from excess salt in one way or another, he explains. “In most cases, they do this by drinking fresh water.” The researchers argue that this was not an option for G. maritimus: the excellent preservation of the skeletons, so far from any land mass that existed at the time, suggests that they were not washed there by water. The team also measured isotopes of the element strontium, which can help date minerals and water in marine samples. Levels in the bones of the ancient animals matched those in seawater at the time, suggesting the creatures “grew up drinking seawater,” the researchers write in the paper.
