Before this , it was believed that fish had first moved onto land â `` either looking for food ( like modern mudskippers ) or to find water when the pond they lived in dried out . It was believed that they later evolved legs , lungs , and other body parts to live better on land . This is in contrast to the earlier view that fish had first invaded the land â '' either in search of prey ( like modern mudskippers ) or to find water when the pond they lived in dried out â '' and later evolved legs , lungs , etc.