Researchers Discover First Known Fully Marine Amphibian from Triassic Period in China

Researchers have discovered two nearly complete skeletons of an amphibian that lived in the sea approximately 237 million years ago during the Triassic Period. Unearthed in China's Guizhou Province, the creature has been named Gerrothorax maritimus.

The species measured about 30 inches, or 75 centimeters, in length and predated the dinosaurs. It featured a flat, disc-shaped and armored body alongside a wide mouth, indicating it was a bottom-dwelling suction feeder that ambushed its prey on a muddy to silty seafloor.

The findings were published in the journal Nature Ecology & Evolution. Paleobiologist Ryosuke Motani of the University of California, Davis, one of the study's leaders, noted the significance of the discovery.

"The most important finding is that there was an early amphibian that lived in the sea full-time," Motani said.

The fossils were recovered from rocks formed from ocean sediment, found near the remains of an ichthyosaur, a marine reptile about 23 feet or 7 meters long named Guizhouichthyosaurus. Because ichthyosaurs were the apex marine predators of the era, researchers suggest the amphibian's bony body armor served as a defense mechanism.

Study co-author Da-yong Jiang of Peking University in China described the physical traits that enabled the creature's hunting style. The flat and wide skull featured a large mouth with many small conical teeth, suited for capturing fish, worms, and cephalopods swimming past.

While modern amphibians rely on permeable skin for breathing and drinking—a process disrupted by seawater's osmotic pressure—Gerrothorax maritimus overcame this limitation through exaptation. Researchers explained that its body armor, which likely evolved for freshwater protection, was repurposed to shield the animal from seawater. The armor would have inhibited seawater absorption through the skin, requiring the animal to drink saltwater through its mouth and filter out salt using its gills.

Chemical analysis of the creature's bones revealed a signature matching Triassic seawater, confirming the animal developed and grew in the ocean.

"This remarkable scientific discovery highlights the value of deep research and exploration in uncovering new data about our planet's history. While this is a paleontology finding rather than a corporate venture, the rigor applied by the research teams demonstrates how persistence and advanced analytical methods can shift our fundamental understanding of established categories." — Dr. Shishir Gupta, Founder & CEO, StartupLanes