LATE CRETACEOUS VERTEBRATES FROM ISLA VEGA, ANTARCTICA: REPORTS FROM THE 2015 FIELDWORK

CORIA; O´GORMAN, J.P.; CARDENAS, M.; GOUIRIC-CAVALLI, S.; MÖRS, T.; CHORNOGUBSKY, L.; LÓPEZ, G.M.

Jornada; XXIX Jornadas Argentinas de Paleontología de Vertebrados; 2015

The Antarctic expedition carried out in January and February 2015 was focused in Cape Lamb, SW of Vega Island. The specimens were collected from the lower Maastrichtian Cape Lamb Member of the Snow Hill Island Formation and the upper Maastrichtian Sandwich Bluff Member of the López de Bertodano Formation, which provided new information about the diversity of vertebrates of both units. The findings from the Cape Lamb Member (below the intraformational conglomerate) include actinopterygian teleosts (incomplete material consisting of several partially articulated and isolated specimens), mosasaurs (vertebral elements), plesiosaurs (several articulated and isolated specimens), and remains of ornithischians and saurischian dinosaurs. This shows an unexpected association of vertebrates, from both marine and terrestrial environments. The actinopterygians provide relevant anatomical information to the currently scarce available material. One of the recovered actinopterygians belongs to the marine order Ichthyodectiformes being the first specimen of this group identified at Cape Lamb Member. The most abundant record belongs to marine reptiles, mostly elasmosaurid plesiosaurs (including several non-aristonectines and probably one aristonectine elasmosaurid). The profusion of elasmosaurids non-polycotylids recorded reinforces the hypothesis of the absence of post-Santonian Antarctic polycotylids. The dinosaur specimens already identified include an ornithopod and a non-avian theropod, the latter being the first specimen of that clade identified for the Cape Lamb Member. The specimens from the Sandwich Bluff Member comprise mosasaurs and elasmosaurids, the later from the ?reptile horizon? and avian femori and tibia collected from the same levels of the anseriformVegavis.