The oldest elasmosaurs (Sauropterygia, Plesiosauria) from Antarctica, Santa Marta Formation (upper Coniacian? Santonian–upper Campanian) and Snow Hill Island Formation (upper Campanian–lower Maastrichtian), James Ross Island

Abstract

Elasmosaurs are recorded for the first time in the Lachman Crags Member(Beta Member) of the Santa Marta Formation (lower Campanian) and inthe Herbert Sound Member of the Snow Hill Island Formation (upperCampanian). These are the first elasmosaurids from James Ross Island,Antarctic Peninsula. These records greatly improve our knowledge of thetaxonomic diversity of plesiosaurs of the Santa Marta Formation and HerbertSound Member of the Snow Hill Island Formation, and extend the lower limitof the record of Elasmosauridae in Antarctica to the lower Campanian, makingthis the oldest record of an Antarctic elasmosaur.