The story
Triadobatrachus massinoti, found in the Early Triassic rocks of Madagascar and described by the French paleontologist Jean Piveteau in 1936, is the oldest known fossil on the frog line. It is about 10 cm long, with a broad, flat, frog-like skull and a short tail. Its backbone has 14 vertebrae in front of the hips, where modern frogs have 9 or fewer, and its short legs were not built for powerful jumping.
Frogs and salamanders share a common ancestor from the Permian, and the frog line then trimmed its spine and lengthened its hind legs and hips into the jumping body plan. Triadobatrachus sits partway along that path. A similar fossil, Czatkobatrachus, comes from Poland at about the same age. True jumping frogs such as Prosalirus appear in the Early Jurassic of Arizona, about 190 million years ago, and the modern groups spread after the breakup of Pangaea.
Why it mattered
- It records a middle stage in how the frog body plan was assembled, a rare snapshot of a transition.
- Frogs survived the end-Triassic and end-Cretaceous extinctions, and later became model animals for biology.
- Their lineage links the first four-legged animals to the thousands of amphibian species alive today.
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