237-Million-Year-Old Gerrothorax maritimus Rewrites Amphibian Sea-Colonization Theory
Updated
Updated · BBC Discover Wildlife · Oct 26
237-Million-Year-Old Gerrothorax maritimus Rewrites Amphibian Sea-Colonization Theory
3 articles · Updated · BBC Discover Wildlife · Oct 26
Summary
Two near-complete skeletons from 237-million-year-old rocks in China’s Guizhou Province identify Gerrothorax maritimus, a stem amphibian that appears to have lived in a fully marine environment.
At least 30 km from any islands, the articulated fossils show little sign of transport, and their chemical signatures match ancient seawater—evidence the animals lived and died at sea rather than washing in from land.
The find challenges the long-held view that amphibians never colonized the ocean because modern species’ salt-sensitive skin causes rapid dehydration and salt overload in seawater.
Researchers say this extinct lineage’s body armor, internal gills and more complex gut may have reduced skin-based salt exchange and enabled a marine lifestyle; no living amphibian among more than 9,100 species is strictly marine.