Aristonectes

Aristonectes is an extinct genus of plesiosaur from the Late Cretaceous of what is now South America and Antarctica. The type species is Aristonectes parvidens, first named by Cabrera in 1941.

Aristonectes has been classified variously since the 1941 description, but a 2003 review of plesiosaurs conducted by Gasparini et al. found that Aristonectes was most closely related to elasmosaurid plesiosaurs like Elasmosaurus. A similar plesiosaur, Morturneria, may be a junior synonym of Aristonectes, the study found.