A Cretaceous continental vertebrate fauna from the Precordillera of La Rioja, Argentina

HECHENLEITNER, E. MARTÍN; LÉA LEUZINGER; TABORDA, JEREMÍAS R. A.; ROCHER, SEBASTIÁN; MARTINELLI, AGUSTÍN G.; FIORELLI, LUCAS E.; DESOJO, JULIA B.; SERGIO DE LA VEGA; SALGADO, LEONARDO; FERNANDEZ BLANCO, M. VICTORIA; BUSCATAMANTE, CARLOS A.; MELO, TOMAZ P.; ACIAR, R. HERNAN; TROTTEYN, M. JIMENA; ACOSTA, LEONEL; MIÑANA, MARCELO

La Plata

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2019

The record of Cretaceous continental vertebrates of Northwest Argentina (NWA) is relativelyscarce compared to Patagonia and southeastern Brazil. In La Rioja, almost all the tetrapodspecimens come from Los Llanos Formation (Upper Cretaceous), in the foothills of SierrasPampeanas. So far, the only exception in western areas was an isolated record of two caudalcentra of a titanosaur sauropod unearthed at the Quebrada de Santo Domingo locality (Ciénagadel Río Huaco Formation, Maastrichtian?), in Precordillera. In 2015 we have started a project,which includes prospection and extraction of fossils at the Mesozoic red beds of this locality, withthe aim of expanding the knowledge about the faunas that inhabited NWA. Here, we report thediscovery of a faunal assemblage composed of saurischian dinosaurs and crocodyliforms. Amongthe first, titanosaur sauropods are the most frequent, with several specimens that belong (at least)to two new species, closely related to ?Aeolosaurini?. In association with some of them, werecovered several teeth of abelisaurid theropods and possible peirosaurid crocodyliforms. Inaddition, we also identified a titanosaur nesting site recorded in several egg-bearing levels. Thesefindings are important, in terms of quality and quantity of specimens, for the Province of La Rioja,as well as NWA. The significant paleolatitudinal distinction between the recent findings from LaRioja and the faunas from Patagonia and Brazil, plus the fact that large areas of southern SouthAmerica were likely flooded by epicontinental seaways at the Late Cretaceous, offer an interestingopportunity to understand their paleobiogeographic relationships.