Fossils reveal a 237-million-year-old amphibian that lived in the open ocean

Researchers from UC Davis, Peking University and the Guizhou Geological Museum described Gerrothorax maritimus, a roughly 237-million-year-old amphibian found in marine sediments in China's Guizhou Province. It is the first fossil evidence of a fully marine amphibian: the armored, disc-shaped animal likely drank salt water and filtered it through gills.

• Fossil dates to about 237 million years ago, Late Triassic
• Animal was nearly three feet long with bony armor
• Strontium isotopes matched Late Triassic seawater
• Fewer than 2% of 8,000 living amphibian species tolerate salt