NEW TITANOSAURIAN (DINOSAURIA, SAUROPODA) RECORD FROM THE UPPER CRETACEOUS (SANTONIAN; BAJO DE LA CARPA FORMATION) OF SOUTHERN NEUQUÉN BASIN (LOS BASTOS, PATAGONIA, ARGENTINA)

CORI, R.; BELLARDINI, F.; SARDELLA, R.

Salta

Jornada; Reunion de Comunicaciones de la Asociacion Paleontologica Argentina; 2022

APA IBIGEO IEBI UNSA IBIGEOP

In the Neuquén Basin, the Bajo de la Carpa Formation (Santonian, Upper Cretaceous) is representedby extended fluvial outcrops of fine sandstones, yielding a diversified archosaurian fossil record.Among the sauropod evidence, three titanosaurian taxa are known, all referred to Colossosauria:Bonitasaura salgadoi, Rinconsaurus caudamirus, and Overosaurus paradoxum. Here we report newsauropod specimens (MMS-PV-46, MMS-PV-47; MMS, Museo Municipal de Ciencias Naturales“Arozena” de Senillosa) from the Los Bastos locality (Senillosa, Neuquén Province), in the southernNeuquén Basin, where a thick succession of sandstones with intercalations of mudstones of the Bajode la Carpa Formation outcrops. The new specimens include three appendicular elements: a largeand almost complete right humerus (MMS-PV-46), a right femur in fragmentary conditions and analmost complete right tibia that we tentatively refer to a smaller individual (MMS-PV-47/1-2). Thebones show some of morphological features that allows us to refer them to titanosaurs sauropods,such as: a distally expanded deltopectoral crest and distal articular surface of the humerus exposedon the anterior portion of the shaft with undivided radial and ulnear condyles, prominent lateralbulge and an elliptical mid-shaft of the femur, and a tibial distal breadth more than twice of the midshaftbreadth. The preliminary phylogenetic analysis recovers these elements deeply nested withinSaltasauroidea. This new record could represent the first saltasauroid titanosaurs for Bajo de laCarpa Formation and one of oldest record of Saltasauroidea from the Neuquén Basin, before thesaltasaurids radiation of the Campanian-Maastrichtian. Pending to further analysis, this newevidence not only improves our knowledge on the sauropod diversity of the Neuquén Basin duringthe Santonian, but also contributes to reconstructing the paleobiogeographical evolution of derivedtitanosaurians on southwestern Gondwana.