237-Million-Year-Old Fossil Reveals First Fully Marine Amphibian, Gerrothorax maritimus

A new study from the University of California, Davis, Peking University, and the Geological Museum of Guizhou reports the first known amphibian that lived entirely at sea. The creature, named Gerrothorax maritimus, was an armored, giant salamander–sized bottom-dweller that inhabited oceans 237 million years ago. The fossils were discovered in Guizhou, China, and represent a major shift in understanding amphibian evolution. Previously, all known amphibians were tied to freshwater or land, but this species adapted to a fully marine lifestyle. The findings suggest that some amphibians evolved to exploit ocean ecosystems far earlier than thought, during the Triassic period. This discovery matters because it rewrites the evolutionary history of amphibians and shows their ecological diversity in ancient seas. The research team's work highlights how fossils from China continue to reshape paleontology. Future studies may reveal more marine amphibians and clarify how they competed with early marine reptiles.