Titanosaur dinosaurs from the Upper Cretaceous of La Rioja province, NW Argentina

Abstract

Our current knowledge of Argentinean titanosaurs outside Patagonia has been effectively limited to the province of Salta (e.g., Saltasaurus). However, several skeletal remains of titanosaurian sauropod dinosaurs have been discovered in the Cretaceous strata of La Rioja Province, northwest Argentina. Herein we describe new titanosaur material from two Upper Cretaceous localities from La Rioja. The first record corresponds to two caudal vertebrae found in the exposures of the Ciénaga del Río Huaco Formation, in the Quebrada de Santo Domingo locality. The largest sample, which includes fragmentary postcranial material of five individuals, was recovered from the Los Llanos Formation, in the Tama locality. The comparative analyses conducted here suggest that most of the specimens should be referred to as Lithostrotia non Saltasaurinae. However, differences between the middle caudal vertebrae from Tama and Quebrada de Santo Domingo suggest that the taxa at each locality are distinct.