MICROESTRUCTURA ÓSEA Y SUMINISTRO SANGUÍNEO DE UNA VÉRTEBRA CAUDAL DE UN ELASMOSÁURIDO (PLESIOSAURIA, ELASMOSAURIDAE) DEL MAASTRICHTIENSE (CRETÁCICO TARDÍO) DE LA ANTÁRTIDA

M. TALEVI

Reptiles Extintos - Volumen en Homenaje a Zulma Gasparini

Asociación Paleontológica Argentina

Año: 2015; p. 195 - 203

BoNE MICRosTRUCTURE AND BLooD sUPPLY oF A CAUDAL VERTEBRA oF AN ELAsMosAURID (PLEsIosAURIA, ELAsMosAURIDAE)FRoM THE MAAsTRICHTIAN (LATE CRETACEoUs) oF ANTARCTICA. Plesiosaurs were reptiles recognized as a derivative fromeosauropterygians clade, whose biochron extends from the Late Triassic to the Late Cretaceous. Plesiosaurs are recorded in marine sedimentsfrom all continents, including Antarctica. Within this group, the degree of compaction and organization of bone tissue are characters thathave 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 thesnow Hill Island Formation (Lower Maastrichtian), Vega Island, Antarctica, with the aim of analyzing how the degree of compaction and remodelingvaries. The results show that the external (fusion of the neural arch to the vertebral body) and the internal ones (extensively remodelledtissue) are consistent, and suggest that the analyzed element has adult characteristics. The element analyzed shows a compactinternal structure and this suggest that (contrary to what previous course) the degree of compaction of a bone would not be a good indicatorof the maturation stage of the individual at least in plesiosaurs. There is a variation of bone tissues within the vertebral body. The caudalvertebrae has a large nutrient foramen in the ventral region that continues inside the vertebral body with a large channel connected withsinus that allows us to infer a conspicuous blood supply inside the vertebral body.