An illustrated rendering of 'Gerrothoroax maritumus,' informed by newly discovered fossil evidence of the creature, which is the first fully marine amphibian on record. AI was sparingly used in the rendering's creation to adjust lighting, brightness, fish skin and amphibian skin. Image: Chen Geng/Guizhou University

Nearly 237 million years ago, a spiky and toothy bottom dweller skulked the Late Triassic oceans that once covered present-day China. What sets this newly discovered giant salamander -sized prehistoric amphibian apart is not its impressive body–it’s that it lived in the ocean. The newly described Gerrothorax maritimus is the first example of a fully marine amphibian in the fossil record, according to a study published today in the journal Nature Ecology & Evolution .

There are currently over 8,000 species of living amphibians, and none have been known to live in fully marine (salt water) environments.…