alt=Drawing of multiple views of a vertebra, very high and laterally compressed, of the fossil sea snake Pterosphenus schucherti, from the original description of the species (Lucas, 1898).|left|thumb|The very high and narrow vertebra of Pterosphenus schucherti hint at the highly specialised aquatic lifestyle of the genus. Pterosphenus is an extinct genus of marine snake of the Eocene period.
alt=Drawing of multiple views of a vertebra, very high and laterally compressed, of the fossil sea snake Pterosphenus schucherti, from the original description of the species (Lucas, 1898).|left|thumb|The very high and narrow vertebra of Pterosphenus schucherti hint at the highly specialised aquatic lifestyle of the genus. Pterosphenus is an extinct genus of marine snake of the Eocene period.
== Classification == Pterosphenus belong to the Alethinophidia snakes, a clade which includes all snakes outside of blind and thread snakes, and more specifically to the extinct Palaeophiidae. Its closest relative is Palaeophis, of which both belong to the subfamily Palaeophiinae. Six species are known, P. schucherti from North America, P. sheppardi from South America, P. schweinfurthi from northern Africa and P. biswasi, P. kutchensis, and P. rannensis from Asia.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).