Keraterpeton

Keraterpeton is an extinct genus of "nectridean" tetrapodomorphs, previously included within the monotypic Keraterpedontidae family, from the Carboniferous period of Europe (Czech Republic, England and Ireland) and North America (United States); it is the oldest known member of the family Diplocaulidae.

The type species is Keraterpeton galvani, named in 1866 as Ceraterpeton by Robert Etheridge and later amended to Keraterpeton in 1868 by Thomas Henry Huxley and Edward Percival Wright; three years earlier (in November 1865), they were authorised by William Bookey Brownrigg to describe some fossil vertebrates in his collection, and among them was NHMING F 14735, the holotype of Keraterpeton galvani, which was discovered in the Jarrow Colliery in County Kilkenny, Ireland. Keraterpeton was a salamander-like creature about 30 cm long. Its tail was remarkably long taking up two thirds of the animal's total length, and was laterally flattened, presumably to aid in swimming. Its skull was round and short, especially when compared to its Permian relative, Diplocaulus. Its hind legs had five toes, and were longer than the forelimbs, which had only four toes.

Keraterpeton was flattened side-ways, which would have helped push itself through the murky waters of the coal swamps in which it lived. The five-toed hind legs were longer than the four-toed fore-feet and the short, rounded skull had eyes set far forward. Although Keraterpeton had a long body, it did not have more vertebrae than most other amphibian species (15–26 on average).