The first record of dermochelyid turtles in the Eocene of Tierra del Fuego, Argentina, provides new information to interpret the evolution of the Weddellian faunas in Western Antarctica

BONA, P.; STERLI, JULIANA; DE LA FUENTE, M. S.; OLIVERO, E.; FERNÁNDEZ, M. S.; REGUERO, M.

SCAR 2022. Antarctica in a changing word

Congreso; SCAR 2022; 2022

The Antarctic Paleogene marine fossil record has been key to reconstructing the evolution of the Weddellian Sea andfinal dismemberment of Southern Gondwana. n this context, Eocene marine vertebrates from Marambio ( =Seymour)lsland have provided valuable information. Herein, we present the first Eocene record of marine reptiles from the southern Atlantic Coast of South America. This corresponds to several postcranial remains of turtles represented by a proximal end of the right humerus, three caudal and one thoracic vertebrae, a fragment of the left pubis, and ten ossicles of dorsal carapace, coming from Leticia Formation (late-middle Eocene) at Cabo Tiburones, Tierra del Fuego, Argentina. These materials show several features such as the size and general morphology of the humerus and vertebrae, and the presence of small, irregular, smooth and unkeeled ossicles, that allow us to assign them to Dermochelyidae indet. Dermochelyids are a cosmopolitan group of cryptodiran turtles, registered from the Late Cretaceous up to the recent, with sorne physiological-biological peculiarities (e.g., endothermy and an exclusive jellyfish-based diet) and characterized by the presence of an osseous carapace formed by ossicles. The new finding from Leticia Formation is an addition to the scarce and extremely fragmentary record of Eocene dermochelyids from the southern seas like those from La Meseta Formation (Antarctica) and Waihao and Burnside formations (New Zealand). This new information allows us to discuss the presence of these turtles in such high latitudes in the past and its implication in the evolution of the Weddellian faunas.