Illustrator signature must be included in all reproductions Ichthyostega tetrapod, illustration. Ichthyostega (centre) was an early tetrapod, one of the first vertebrates to evolve limbs and be capable of moving around on land. It lived in the Late Devonian (365 to 360 million years ago). It was a descendent of lobe-finned fishes and an ancestor of amphibians. Fossils have been found in Greenland.