The first tetrapods probably evolved in the Emsian stage of the Early Devonian from Tetrapodomorph fish living in shallow water environments. The very earliest tetrapods would have been animals similar to Acanthostega, with legs and lungs as well as gills, but still primarily aquatic and unsuited to life on land.

When did tetrapods first evolve?

The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes.

What is the vertebrate ancestor to all tetrapods?

In a strict evolutionary sense, all tetrapods are essentially “limbed fish,” because their ultimate vertebrate ancestor is a fish. All tetrapods share a variety of morphological features.