News by Levels · Level 3 · Student worksheet

Chinese Fossils Suggest an Early Amphibian Adapted to the Open Sea

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A study of two skeletons from Guizhou, China, suggests that an ancient amphibian lineage reached the open sea. The newly named Gerrothorax maritimus lived roughly 237 million years ago, long before today's frogs and salamanders. The research appeared in Nature Ecology & Evolution on October 26.

Its bony armour covered a flattened body. The skeletons were preserved in rocks that formed away from land, while chemical signatures in the fossils resemble those of seawater from the same period. Together, the observations support the researchers' interpretation that the animal lived in a marine environment.

It may be the first fully marine amphibian known from the fossil record. The proposed role of its armour and organs in tolerating salt remains a hypothesis; the fossils do not preserve every detail of its physiology.

Source: University of California, Davis, 2026-10-26. https://www.ucdavis.edu/curiosity/news/researchers-unearth-fossil-evidence-first-fully-marine-amphibian

Read and practise

1. Why do the researchers interpret the animal as marine?

   1. Its fossils occurred away from ancient land, and their chemical signatures resemble seawater.
   2. The rocks formed near an ancient shore, and the fossils resemble seawater chemically.
   3. The rocks formed away from land, and the fossils resemble freshwater chemically.

2. Which claim does the text identify as a hypothesis rather than a directly established fact?

   1. The proposed role of armour and organs in handling salt
   2. The similarity of fossil chemical signatures to ancient seawater
   3. The preservation of two skeletons in Guizhou

Your turn

Describe two observations supporting marine life and distinguish them from the proposed salt-tolerance mechanism.

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Read online: https://newsbylevels.com/news/armoured-amphibian-fossils-ocean-china-october-2026/level-3/