A frog-like amphibian from the dinosaur era lived entirely at sea
Two skeletons found in China reveal that Gerrothorax maritimus, a Triassic amphibian, was the first fully marine one. The key was a bony armor.
English · Original discussion in Spanish · Published
Two nearly complete skeletons found in China show that the amphibian Gerrothorax maritimus lived permanently in the sea 237 million years ago. It is the first amphibian known to be fully marine and forces a rethink of the idea that these animals never colonized the oceans.
The finding, published in **Nature Ecology & Evolution**, describes two nearly complete skeletons of an amphibian that lived **237 million years ago**, in the Triassic. The animal was called **Gerrothorax maritimus** and had a flattened body, a bony armor and a mouth with which it probably sucked in its prey. Until now, no known amphibian had spent its entire life in the sea.
## Why no amphibian lives in the sea
Today there are more than **8,000 species** of amphibians among frogs, salamanders and caecilians. None spends its whole life in the sea. The obstacle lies in their skin: it is permeable, absorbs water and exchanges gases with the environment. That is an advantage in humid land or freshwater, but it becomes a problem in the ocean. The high salt concentration promotes water loss from the body and makes survival difficult.
The question was whether any ancestor had solved that problem. The answer lies in these two skeletons.
## The armor that was not meant for the sea
As **Ryosuke Motani**, a professor at the University of California in Davis and one of the authors of the study, explains to EL MUNDO, the key lay in an adaptation that originally had nothing to do with living in the ocean. "The most important message of this study is that amphibians of the past found a way to live permanently in the sea and that this adaptation was possible thanks to chance," the researcher notes.
The animal's bony armor and flattened body, traits that probably served other functions, turned out to be compatible with marine life. Chance, not an evolutionary race toward the ocean, peine that door.
## What the discovery changes
The finding forces a revision of a deeply rooted idea about the evolution of these animals: that the sea was always closed to them. **Gerrothorax maritimus** shows that there was at least one exception, and that it was long-lasting. It was not a brief foray nor a larval stage: the two skeletons point to a fully marine amphibian.
The finding, published in **Nature Ecology & Evolution**, describes two nearly complete skeletons of an amphibian that lived **237 million years ago**, in the Triassic. The animal was called **Gerrothorax maritimus** and had a flattened body, a bony armor and a mouth with which it probably sucked in its prey. Until now, no known amphibian had spent its entire life in the sea.
## Why no amphibian lives in the sea
Today there are more than **8,000 species** of amphibians among frogs, salamanders and caecilians. None spends its whole life in the sea. The obstacle lies in their skin: it is permeable, absorbs water and exchanges gases with the environment. That is an advantage in humid land or freshwater, but it becomes a problem in the ocean. The high salt concentration promotes water loss from the body and makes survival difficult.
The question was whether any ancestor had solved that problem. The answer lies in these two skeletons.
## The armor that was not meant for the sea
As **Ryosuke Motani**, a professor at the University of California in Davis and one of the authors of the study, explains to EL MUNDO, the key lay in an adaptation that originally had nothing to do with living in the ocean. "The most important message of this study is that amphibians of the past found a way to live permanently in the sea and that this adaptation was possible thanks to chance," the researcher notes.
The animal's bony armor and flattened body, traits that probably served other functions, turned out to be compatible with marine life. Chance, not an evolutionary race toward the ocean, peine that door.
## What the discovery changes
The finding forces a revision of a deeply rooted idea about the evolution of these animals: that the sea was always closed to them. **Gerrothorax maritimus** shows that there was at least one exception, and that it was long-lasting. It was not a brief foray nor a larval stage: the two skeletons point to a fully marine amphibian.
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Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (1 replies).
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