Paleogene Chondrichthyes of Antarctica: state of the art and perspectives.

CHARNELLI, MARTINA; GOUIRIC CAVALLI, S.; REGUERO, MARCELO; ALBERTO LUIS CIONE

Congreso; SCAR Open Science Conference; 2022

Chondrichthyes (chimeras, rays, and sharks) inhabit mainly marine warm water, with few freshwaters and/or marine deep-water species. Despite currently, the group gather more than one thousand species, only six species have been recorded in Argentine Antarctic sector. Here we present advances of the doctoral thesis of the senior author which deals whit the systematic and taxonomy of Paleogene Chondrichthyes housed at the Vertebrate Paleontology Collections of the Museo de La Plata. Paleogene chondrichthyans at Seymour Island have been retrieved from the La Meseta (Eocene) and the Submeseta formations (Eocene – Oligocene). They are represented by twenty-five genera and fourteen species based mainly on isolated teeth. Through the years, Argentinian geologists used several informal units to divide the La Meseta Formation. Many of these units are unprecise and today obsolete. Thus, allocating specimens to a precise unit is problematic. A key section of the thesis work consists of the homologation and standardization of the geological unit’s nomenclature. This task highly time-consuming and sometimes tricky consists of comparing the different models proposed through the years by combining new and old information. Two of the difficulties found during this process were: localities with two or more names and localities lacking geographical allocation. To date, the information relative to the provenance of the specimens, which was obtained from literature and collection labels, was standardized, and actualized. This is a relevant first approximation which is key for further taphonomic and evolutionary history of the Antarctic Paleogene chondrichthyans.