Pterosphenus

Pterosphenus belong to the Palaeophiid snakes, a clade which includes all snakes outside of blind and thread snakes. Its closest relative is Palaeophis, of which both belong to the subfamily Palaeopheinae. Two species are known, P. schucherti from North America, and P. schweinfurthi from northern Africa.

While only known from partial remains, enough has been found of Pterosphenus to suggest it was a large reptile over 4 metres. It body was laterally compressed as an adaptation to pelagic life.

A marine ocean dweller, Pterosphenus lived in the shallow seas of both the future eastern US (fossils are known from Texas, Louisiana, Mississippi, and Arkansas and up north to New Jersey), and northern Africa in the Tethys Ocean (fossils are known from Morocco,[3] Libya,[4] and Egypt[5]). Pterosphenus was a top predator of the ecosystem, likely preying on fish and molluscs found in the same area.

It is certain that Pterosphenus would have encountered basal cetaceans of the time like Zygorhiza, Dorudon, and Basilosaurus, though its likely a mixed of niche partitioning and living in different areas in the case of Basilosaurus (which lived in estuary ecosystems according to recent finds) would prevent competition between the species.