Procynosuchus

Procynosuchus (Greek: "Before dog crocodile") was a cynodont, a group that was ancestral to mammals. Procynosuchus, specifically, belonged to a group of cynodonts called Procynosuchidae, one of the earliest cynodonts. It lived in the Late Permian world. Procynosuchus was unusual in that it was semi-aquatic, like seals or crocodiles of today, whereas most cynodonts, such as Cynognathus, were terrestrial. Procynosuchus swam by wiggling the front and rear ends of its stiff spine, just like a crocodile, and paddled with its webbed, otter-like hands and feet. Procynosuchus was probably a piscivore, or fish eater. It was 60 cm long (2 feet).