Ichthyostega is an evolution and related to the Tiktaalik. It was a Devonian Amphibian that appeared at the end of the age. It had strong back legs which allowed them to swim in the water. Like modern day whales and dolphins it has to come to the surface to take a breath of fresh air. It preyed on mostly fish like Bothriolepis. It will ambush the fish and take it out of the water. Ichthyostega was very much comfortable on land, but like all amphibians it has to return to the water to keep moist and lay there eggs.