New dinosaur records from the upper cretaceus of Vega Island

RODOLFO ANIBAL CORIA; JOSE O´GORMAN; MAGALI CARDENAS

Diamante

Jornada; XXIX Jornadas Argentinas de Paleontología de Vertebrados; 2015

Here we report the finding of dinosaur remains collected from the lower levels of the Cape Lamb Member (Snow Hill Island Formation, Lower Maastrichtian, Late Cretaceous), which outcrop at Cape Lamb, SW of Vega Island. The remains were found in sandstones with abundant fossils of plesiosaur and marine invertebrates. One of the specimens (MLP-xx-xx-xx) consists in 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 (MPL-xx-xx-xx) was collected from the site where ornithopod remains were recovered in the early 90s. 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 allow referring this specimen to a mid-sized theropod dinosaur. The symmetry of the distal articular surfaces prevents to assign the specimen to the Abelisauroidea. Previous known Antarctic Late Cretaceous non-avian theropods consist on an isolated distal tibia from Hidden Lake Fm and a complete hind limb of a small dromaeosaur from the Snow Hill Fm (James Ross Is.), the latter likely from similar stratigrahical levels of the specimen here reported. The specimens suggest a greater diversity of Antarctic Cretaceous dinosaurs than previously known encouraging further explorations in the Snow Hill Island Fm.