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, J.; DE LA FUENTE, M. S.; OLIVERO, EDUARDO; FERNÁNDEZ, M. S.; REGUERO M. A.

Nueva Delhi

Conferencia; 10 SCAR Open Science Conference; 2022

The Antarctic Paleogene marine fossil record has been key to reconstructing the evolution of the Weddellian Sea andfinal dismemberment of Southern Gondwana. In this context, Eocene marine vertebrates from Marambio (=Seymour)Island have provided valuable information. Herein, we present the first Eocene record of marine reptiles from the southernAtlantic Coast of South America. This corresponds to several postcranial remains of turtles represented by a proximal endof the right humerus, three caudal and one thoracic vertebrae, a fragment of the left pubis, and ten ossicles of dorsalcarapace, coming from Leticia Formation (late-middle Eocene) at Cabo Tiburones, Tierra del Fuego, Argentina. Thesematerials show several features such as the size and general morphology of the humerus and vertebrae, and thepresence 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 some physiological-biological peculiarities (e.g., endothermy and an exclusive jellyfish-based diet) andcharacterized by the presence of an osseous carapace formed by ossicles. The new finding from Leticia Formation is anaddition to the scarce and extremely fragmentary record of Eocene dermochelyids from the southern seas like thosefrom La Meseta Formation (Antarctica) and Waihao and Burnside formations (New Zealand). This new information allowsus to discuss the presence of these turtles in such high latitudes in the past and its implication in the evolution of theWeddellian faunas.