First marine animal a ‘chunky salamander’

By the Editorial Team · Tuesday, October 27, 2026

Researchers have identified two well-preserved fossils of Gerrothorax maritimus, the first fully marine amphibians known to have lived about 237 million years ago in the deep ocean. This discovery reveals that some amphibians adapted to salty, open-ocean environments during the Triassic period, challenging the idea that amphibians were confined to freshwater habitats.

Two exceptionally well-preserved fossils dating back approximately 237 million years have been identified as the first fully marine amphibians ever discovered, according to a recent study published in Nature Ecology & Evolution. The species, named Gerrothorax maritimus, inhabited deep ocean waters during the Triassic period, marking a significant departure from the freshwater habitats typical of modern amphibians.

Measuring about three feet in length, Gerrothorax maritimus resembled a bulky, armored salamander with a flat skull. The species possessed specialized gills capable of regulating salt levels, enabling it to survive in a marine environment. Its large mouth was adapted for filtering saltwater and capturing prey. Unlike contemporary amphibians, which are generally confined to freshwater ecosystems due to their sensitive, salt-intolerant skin, this ancient creature had evolved to withstand the challenges of a saltwater habitat permanently.

The fossils were uncovered in China’s Guizhou Province, specifically within the Falang Formation—a geological formation representing a deep ocean floor from the Triassic era. Notably, the discovery site was located roughly 120 miles from the closest ancient landmass, reinforcing the conclusion that these amphibians lived entirely in the ocean rather than being washed out to sea post-mortem. Detailed chemical analysis and the preservation of intact finger bones support the interpretation that Gerrothorax maritimus was a true marine species.

Scientists described the animal as encased in comprehensive body armor and adapted with gills that regulated salt intake. Ryosuke Motani, a professor at the University of California, Davis, specializing in Earth and Planetary Sciences, highlighted the uniqueness of the find. He pointed out that while much research has focused on marine reptiles and fish from the same fossil beds, the identification of a fully marine amphibian represents an unusual and novel addition to the prehistoric fauna of the region.

Modern amphibians, numbering over 8,000 species worldwide, typically show limited to no tolerance for saltwater environments. Fewer than 2 percent exhibit partial salt tolerance, and none are known to live entirely in marine settings. Gerrothorax maritimus’s robust, "chunky" body shape contrasts with that of current giant salamanders, which tend to be more elongated. Its adaptation for a marine lifestyle offers new insight into the ecological diversity and evolutionary capacity of early amphibians.

The discovery challenges prevailing assumptions about amphibian habitat limitations and expands understanding of ancient marine ecosystems during the Triassic period. It also suggests that amphibians experimented with a wider range of environments than previously recognized, including long-term survival in open ocean conditions.

This article was reported by synthesizing coverage from multiple independent news outlets to present a balanced, unbiased account. Read about our editorial standards. Spotted an error? Let us know.