Tetrapods

Tetrapods evolved from a group of semiaquatic animals within the tetrapodomorphs which, in turn, evolved from ancient lobe-finned fish (sarcopterygians) around 390 million years ago in the Middle Devonian period. Early tetrapodomorphs were transitional between lobe-finned fishes and true four-limbed tetrapods, though most still fit the body plan expected of other lobe-finned fishes. The oldest fossils of four-limbed vertebrates (tetrapods in the broad sense of the word) are trackways from the Middle Devonian, and body fossils became common near the end of the Late Devonian, around 370–360 million years ago. These Devonian species all belonged to the tetrapod stem group, meaning that they did not belong to any modern tetrapod group.