# Discovery of First Fully Marine Amphibian Fossil Ancient Gerrothorax maritimus fossil reveals unique adaptations for living in Triassic oceans. - **Source:** [The Independent Science](https://www.independent.co.uk/news/science/rss) - **Published:** 2026-10-28 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/c1378b2b-11ef-4278-8637-55eaef81fe3e ## Ancient Marine Amphibian Discovery Researchers from UC Davis, Peking University, and the Geological Museum of Guizhou identified the Gerrothorax maritimus fossil. Dating back 237 million years to the Late Triassic, this creature represents the first known amphibian to inhabit fully marine environments. The discovery challenges existing biological assumptions regarding the habitat limitations of modern amphibian species. ## Unique Physical Characteristics The animal measured approximately 90cm in length and possessed a distinctively chunky, disc-shaped body. Unlike modern elongated salamanders, this species was covered in heavy bony armour. This protective layer likely served as a defense mechanism against predators like ichthyosaurs, while also potentially assisting in managing its interaction with the surrounding saltwater environment. ## Suction Feeding Mechanism Analysis of the skull structure suggests the creature was a bottom-dwelling suction feeder. It likely waited on the ocean floor, using suction to capture prey, a method comparable to the modern wobbegong shark. This specialized feeding strategy allowed it to thrive in deep-sea ecosystems alongside marine reptiles and various fish species. ## Physiological Adaptation Challenges Modern amphibians generally avoid marine environments because their permeable skin makes salt regulation difficult. While less than 2 percent of modern species tolerate some salinity, they typically require freshwater to recover. Gerrothorax maritimus likely bypassed these limitations through its bony armour, which may have reduced water absorption through the skin surface. ## Salt Regulation Hypotheses Researchers propose that the creature may have ingested seawater through its mouth, processing it via the digestive system rather than the skin. Furthermore, gills associated with the Gerrothorax genus might have functioned to remove excess salt from the body. These adaptations allowed the animal to maintain homeostasis in a fully marine habitat. ## Geological Evidence of Habitat The fossils were discovered in deep-sea sediments in a nearly complete state, including delicate fingers and limbs. Professor Ryosuke Motani noted that the preservation of these extremities indicates the animals died near their living environment. This contradicts the theory that carcasses were transported from land, confirming their permanent residence in the ocean. ## Geochemical Isotope Analysis The research team performed geochemical analyses on the fossilized remains to confirm the environment. The proportions of strontium isotopes found within the fossils closely matched those present in the oceans during the Late Triassic period. This chemical evidence provides robust support for the conclusion that the species was indeed a marine dweller. ## Evolutionary Significance This discovery offers rare insights into the evolutionary history of amphibians and their past capacity to occupy diverse habitats. By identifying how ancient species adapted to marine conditions, scientists can better understand the limitations of modern amphibians. The study, supported by the National Natural Science Foundation of China, opens new avenues for paleoecological research. ## Sources covering this story - https://www.independent.co.uk/news/science/fossil-amphibian-sea-ocean-salamander-gerrothorax-maritimus-b3074660.html — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._