Microestructura ósea y suministro sanguíneo de una vértebra caudal de un Elasmosaurido (Plesiosauria, Elasmosauridae) del Maastrichtiano (Cretácico Tardío) de la Antártida

Abstract

Plesiosaurs were reptiles recognized as a derivative from eosauropterygians clade, whose biochron extends from the Late Triassic to the Late Cretaceous. Plesiosaurs are recorded in marine sediments from all continents, including Antarctica. Within this group, the degree of compaction and organization of bone tissue are characters that have been used to determine ontogenetic stages from which it differs a typical juvenile pattern (dense tissue paquiostotic), adult pattern (light osteoporotic tissue). In this contribution, different cross sections were made to caudal vertebrae from a plesiosaur recovered from the snow Hill Island Formation (Lower Maastrichtian), Vega Island, Antarctica, with the aim of analyzing how the degree of compaction and remodeling varies. The results show that the external (fusion of the neural arch to the vertebral body) and the internal ones (extensively remodelled tissue) are consistent, and suggest that the analyzed element has adult characteristics. The element analyzed shows a compact internal structure and this suggest that (contrary to what previous course) the degree of compaction of a bone would not be a good indicator of the maturation stage of the individual at least in plesiosaurs. There is a variation of bone tissues within the vertebral body. The caudal vertebrae has a large nutrient foramen in the ventral region that continues inside the vertebral body with a large channel connected with sinus that allows us to infer a conspicuous blood supply inside the vertebral body.