The first record of Tuarangisaurus (Sauropterygia, Plesiosauria) from the Maastrichtian of the Lefipán Formation, Chubut, Argentina

Elasmosaurids represent the most diverse clade of plesiosaurians during the Campanian-Maastrichtian. We report a new specimen with a well-preserved cranium and postcranium from the Maastrichtian levels of the Lefipán Formation, Chubut Province, Argentina, referred to Tuarangisaurus keyesi. This species was previously known only from Campanian-Maastrichtian deposits of New Zealand. Phylogenetic analysis recovers Tuarangisaurus keyesi as the basalmost member of Weddellonectia. The hyoid apparatus is preserved and consists of a single ossified element identified as ceratobranchial I, comparable to the condition observed in other plesiosaurians. The morphology of this element is consistent with a ram-feeding strategy.