NEW DINOSAUR RECORDS FROM THE UPPER CRETACEOUS OF VEGA ISLAND, ANTARCTICA

CORIA, R.; O´GORMAN, J.P.; CÁRDENAS, M.; MÖRS, T.; CHORNOGUBSKY, L.; LÓPEZ, G.M.

Jornada; XXIX Jornadas Argentinas de Paleontología de Vertebrados; 2015

Here we report the finding of dinosaur remains from the lower levels of the Cape Lamb Member (Snow Hill Island Formation, lower Maastrichtian, Upper Cretaceous) that crop out at Cape Lamb, SW of Vega Island. The remains were found in mudstones with abundant fossils of marine invertebrates and plesiosaurs. The specimen MLP 15-I-7-1 consists of a proximal end of a right tibia and astragalus identified as belonging to a mid-sized ornithopod, due a reduced cnemial crest, a mid-positioned fibular process and an astragalus with a low ascending process and high caudal process. The specimen contrasts in size with another ornithopod records known from the same formation. The other specimen (MLP 15-I-7-2) was collected from the site where ornithopod remains were recovered in the early 1990s. It corresponds to an isolated pedal phalanx, probably the first of digit III. The deeply concave, triangular outlined proximal articular surface, the constricted shaft, the well-developed distal gynglimoid and the high pneumaticity suggest this specimen may belong to a mid-sized theropod dinosaur. Previously known Antarctic Late Cretaceous non-avian theropods consist of an isolated distal tibia from the Hidden Lake Formations and a fragmentary hind limb of a dromaeosaur from the Snow Hill Island Formarions (James Ross Island). The latter comes from the Cape Lamb Member as the specimens reported here. The new findings indicate a greater diversity of Antarctic Cretaceous dinosaurs than that one previously known, encouraging further exploration in the Snow Hill Island Formation at Vega Island