237-Million-year-old Fossils Reveal a Sea-dwelling Amphibian

WHO:

Nature - Researchers provisionally named the fossil species *Gerrothorax maritimus*, a temnospondyl amphibian.

Nature - Steve Brusatte, a palaeontologist and evolutionary biologist at the University of Edinburgh, called the discovery “potentially a revolutionary discovery” and said that if *Gerrothorax* was fully marine, it would be “a game-changer.”

Nature - Ryosuke Motani, a palaeobiologist at the University of California, Davis, co-authored the study and discussed amphibians’ salt tolerance.

BBC Wildlife Magazine - Lipin Diao and colleagues studied the fossils and wrote about the species’ possible marine adaptations.

Phys.org - The study involved scientists from the University of California, Davis; Peking University; and the Geological Museum of Guizhou.

WHAT:

Nature - Researchers reported evidence that *G. maritimus* lived in the sea; its flattened, heavily armoured body measured about 74 centimetres long.

BBC Wildlife Magazine - Two nearly complete skeletons were identified as a previously unknown species. The larger measured nearly 75 centimetres; the other was approximately 48 centimetres.

BBC Wildlife Magazine - The discovery was described as the first stem amphibian found in a fully marine setting.

Phys.org - Researchers described the animal as an armoured, giant-salamander-sized, bottom-dwelling ocean creature and reported fossil evidence that it lived entirely at sea.

WHERE:

Nature - The fossils were found in what is now Guizhou Province, China; the area was a salty sea during the Late Triassic.

BBC Wildlife Magazine - The skeletons came from rocks in Guizhou Province deposited at least 30 kilometres from any islands.

WHY:

Nature - Researchers argued the animals were not washed from land because their skeletons were exceptionally preserved and found far from land; their bone strontium isotope levels matched those of seawater.

BBC Wildlife Magazine - The species’ body armour may have limited water, gas, and salt exchange through the skin, while internal gills and a more complex gut may have helped it manage salt.

HOW:

Nature - Researchers measured strontium isotopes in the bones; the results matched ancient seawater and suggested the animals “grew up drinking the seawater.”

BBC Wildlife Magazine - The skeletons were articulated and showed little evidence of transport; preserved fingers were cited as evidence the animals lived near where they were buried.

BBC Wildlife Magazine - The animal’s large mouth suggests it may have fed by suction on the seafloor. Its soft tissues were not preserved, leaving other aspects of its physiology unknown.

BBC Wildlife Magazine - The fossils were excavated by local fossil collectors.

(UPDATED October 27, 2026 02:13 UTC)

Researchers have identified *Gerrothorax maritimus*, an armoured, salamander-sized amphibian that appears to have lived entirely in the sea, a first for a stem amphibian. Two unusually well-preserved skeletons were found in rocks in what is now China’s Guizhou Province, far from land, and strontium in their bones matched ancient seawater. Its armour may have helped control salt exchange, while internal gills and a more complex gut may also have aided salt management, though its soft tissues were not preserved.