Eryops megacephalus

Eryops, measuring up to 2 metres in length and weighing 90 kg, is one of the largest amphibian vertebrates from the end of the Palaeozoic. 
It retained many ancestral characteristics (eyes and nostrils located on the top of the head, flat massive skull, etc.) but acquired numerous characteristics that allowed it to support the weight of its body out of water (short stocky legs, reinforced vertebral column, etc.). Today we know that it had only four toes on its front feet, contrary to what we see in the fossil on display and in many older illustrations. 
This amphibious animal was dependent on aquatic environments. A carnivore, Eryops ambushed its prey in the water, just like crocodiles today.

Resin cast donated by the American Museum of Natural History (New York).