The armored amphibian Gerrothorax maritimus was able to survive in salty seas due to its body armor.

Evolutionary ‘game-changer’: weird armoured amphibian lived in ancient seas https://www.nature.com/articles/d41586-026-03440-1 The creature’s armour cladding probably enabled it to tolerate the salty seas of the Late Triassic.

Evolutionary 'game-changer': weird armoured amphibian lived in ancient seas Amphibians were able to live in the sea 237 million years ago, according to research published today in Nature Ecology & Evolution1. Two fossils of a type of primitive amphibian from a group called temnospondyls were found in what is now Guizhou province in China — which would have been a salty sea during the Late Triassic period. The researchers have provisionally named the species Gerrothorax maritimus. The 74-centimetre-long creatures had flattened bodies and were almost completely covered by body armour. There are more than 8,000 species of modern amphibians, but none of them lives exclusively in a marine environment. https://www.nature.com/articles/d41586-026-03440-1