congresos y reuniones científicas
New sauropod remains from the Late Cretaceous of Los Llanos Formation, La Rioja, Argentina
Zapala-El Chocón
Congreso; XXVIII Jornadas Argentinas de Paleontología de Vertebrados; 2014
Institución organizadora:
Asociación Paleontológica Argentina
To date, the fossil record of Cretaceous sauropod dinosaurs in La Rioja Province (Argentina) is from the Cienaga del Río Huaco and Los Llanos formations. Recent field works conducted by the Geosciences Group from CRILAR in the exposures of the Los Llanos Formation, located near the village of Tama (Dpto. V.A. Peñaloza) led to the discovery of new titanosaur poscraneal materials. The partially remains were discovered in the lower levels of the Upper Member of this formation. The skeletal material consists of axial (a dorsal vertebra, at least 8 caudal vertebrae, and several ribs) and appendicular elements (a humerus, ulna, ilium, pubis and at least 3 femora) from several individuals of different age groups. These remains are found mostly disarticulated (excluding the caudal vertebrae) displaying various diagenetic and taphonomic grades (e.g., recrystalization, biogenic alteration, and weathering). The best preserved material exhibits features typically known for titanosaurs, such as an ubiquitous pleurocoel in the first dorsal vertebra, and procoelous caudal vertebrae. In addition, other squeletal elements are remarkably similar to those from derived titanosaur genera, namely Rapetosaurus, Bonitasaura and Mendozasaurus. This new record, coupled with the recent discovery of an Upper Cretaceous microfossils association and cranial material of a notosuchian crocodyliform, strengthens previous interpretations of a Late Cretaceous age for the Los Llanos Formation. Finally, given the significant paleolatitudinal distinction between the Los Llanos fauna and those of Brazil and Patagonia, these new fossils are pivotal for the understanding of the paleobiogeographical relationships of the South American titanosaurs.