Acanthostega is one of the earliest known tetrapods. it has many fishlike features, such as a long, flat tail that was good for swimming, and gills for breathing underwater. But it also had what seem to be land living features, like its four legs, a large rib age for holding bug lungs.
Usage of legs Edit
However, scientists now think that Acanthostega's limbs were actually used for walking in shallow fast flowing streams rather than for walking on land. The limbs could have also been used for swimming. The front limbs could have held onto underwater plant roots and been used to search for food.