The Discovery
Researchers examining 237-million-year-old rock layers in China's Guizhou Province identified a previously unknown species of stem amphibian. The discovery was based on two remarkably well-preserved, articulated skeletons found in rocks deposited at least 30 kilometers away from any ancient islands. These rocks also contained fossils of fully marine reptiles, including ichthyosaurs. Chemical analyses of the preserved skeletons matched the signatures of ancient seawater, confirming that these animals spent their lives in an oceanic environment. Scientists named the species Gerrothorax maritimus, utilizing the Latin word for "of the sea."
What Scientists Found
The fossilized skeletons revealed that G. maritimus had a flattened, heavily armoured body structure. The larger specimen measures nearly 75 centimeters in length—roughly the size of a typical house cat—while the smaller 48-centimeter skeleton is exposed belly-side up, giving researchers a detailed view of its armoured underside. The animal's broad mouth suggests it functioned as a bottom suction feeder, waiting on the seafloor to draw in prey much like modern wobbegong sharks do. Unlike living amphibians, G. maritimus possessed internal gills and a more complex gut, though the absence of soft tissues leaves other physiological details unknown.
Why It Matters
Modern amphibians comprise more than 9,100 living species, including frogs, salamanders, newts, and caecilians. None of these modern species can survive in full-strength seawater because they breathe through thin, moist skin. In salt water, osmotic pressure draws vital moisture out through their skin, quickly causing fatal dehydration. The discovery of G. maritimus demonstrates that prehistoric stem amphibians overcame this barrier. Researchers suggest that its full-body armour restricted skin-based water and salt exchanges, forcing the animal to rely on its internal gills and gut to regulate salt levels. This adaptation permitted an extinct amphibian lineage to successfully cross into marine habitats, expanding our understanding of prehistoric life.
Source: prehistoric animals new study - BingNews · Published October 26, 2026 · Photo by Moritz Mentges on Unsplash