The first tetrapods (from a traditional, apomorphy-based perspective) appeared by the late Devonian, 367.5 million years ago. The specific aquatic ancestors of the tetrapods and the process by which they colonized Earth's land after emerging from water remains unclear.

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.

How did the first tetrapods come onto land?

Some of the earliest tetrapods, like Ichthyostega were quite cumbersome on land, and likely spent most of their time in the comfort of water. These first tetrapods came from an ancient lineages of fishes called the Sarcopterygii or Lobe-Finned Fish, of which only a few survive today.