Ancient Amphibian Lived Entirely in Saltwater
Fossils reveal Gerrothorax maritimus, a 237-million-year-old creature, may be the first known amphibian to live without land or freshwater.
Updated on Nov. 6, 2026 in Aquariums
Researchers identified Gerrothorax maritimus as the first known amphibian to have lived without access to land or freshwater, based on two fossils from the late Triassic Period. Chemical analysis of the fossil bones indicated the animal ate seafood and drank seawater.
Why it matters
Of the more than 8,000 amphibians known today, none live solely in saltwater, so the discovery challenges assumptions about where amphibians could survive. It suggests other marine amphibians may exist in environments that paleontologists have not yet examined.
The study examined two fossils, each about 70 centimeters long and armored with bony plates, found in a former seabed roughly 30 kilometers from ancient land. Strontium levels in the bones matched those of the Triassic ocean, but the sample size is limited to two specimens.
The players
Ryosuke Motani
Ryosuke Motani is a paleobiologist at the University of California, Davis who led the study of the fossils.
Lachlan Hart
Lachlan Hart is a paleobiologist at the University of New South Wales, Sydney who was not involved in the research.
The details
The fossils from the late Triassic Period show the animal had a jaw that lifted upward to create suction for catching fish and small creatures. Its bony body armor likely evolved for defense, and the hard plates may have helped prevent water loss.
Timeline
Gerrothorax maritimus lived about 237 million years ago during the late Triassic Period.
Findings were reported October 26 in Nature Ecology & Evolution.
Seasonal Patterns
The find extends the documented range of amphibian habitats into the Triassic seas, a period when marine reptiles and fish dominated ocean ecosystems. It also suggests that ancient marine environments may hold amphibian fossils that have gone unexamined by paleontologists.
The discovery may influence future paleontological surveys by prompting researchers to examine ancient marine deposits for amphibian remains. Its practical impact on everyday life is limited, but it refines understanding of how vertebrates adapted to the ocean.
The takeaway
Ancient fossils can overturn assumptions about where life once thrived, so previously overlooked environments deserve closer study. Attention to marine deposits may reveal more surprises about early vertebrate evolution.
Further reading
Explore more about Aquariums to see how marine environments support diverse life.
Source note: This article includes information reported by Science News.
