Nectridea

Nectridea is the name of an extinct order of lepospondyl tetrapods from the Carboniferous and Permian periods, including animals such as Diplocaulus. In appearance, they would have resembled modern newts or aquatic salamanders, although they are not amphibians. They had long, flattened tails to aid in swimming, and well-developed hind limbs, with a full set of five toes each. Their forelimbs were somewhat reduced, however, and like modern amphibians, typically had only four toes each.