Rediagnosis of Rinconsaurus caudamirus Calvo and Gonzáles Riga (Dinosauria, Sauropoda) from the Anacleto Formation (Upper Cretaceous: Campanian) of Rincon de los Sauces (Neuquén, Argentina)

AGUSTÍN PÉREZ MORENO; JOSÉ LUIS CARBALLIDO; ALEJANDRO OTERO; LEONARDO SALGADO; CALVO, JORGE O.; LEONARDO FILIPPI

Congreso; Reunión de Comunicaciones Asociación Paleontológica Argentina 2018; 2018

Despite its great diversity, knowledge of many aspects of titanosaur sauropod anatomy is relatively poor, in part due to thefragmentary nature of many species. Rinconsaurus caudamirus is represented by several partial skeletons from a single locality from the Anacleto Formation (Upper Cretaceous, Campanian), in the north of Neuquén province, Argentina. Since itsoriginal description, this taxon has not been subjected to an exhaustive revision, which has raised a number of questionsabout its taxonomical status. Among them, stand out the fact that characters 1 and 2 from the three originally used fordiagnosing it showed to be more widespread distributed among Titanosauria. Additionally, an important morphologicalvariability is observed among caudal vertebrae, making necessary the revision of the assemblage originally stated out. Herewe present a revision of the postcranial material of Rinconsaurus based on new observations and comparisons with relatedtaxa. The observed morphological differences in caudal vertebrae could be well explained as the product of different ontogenetic stages and serial variations, whereas three new autapomorphic character were detected (1-posterior cervicals withthe ventral end of the spinoprezygapohyseal lamina intercepting the intraprezygapophyseal lamina; 2-anteriormost caudals with two marked lateral faces with the lower face strongly constricted ventrally; 3-caudal vertebrae with the anteriorarticular surface markedly higher than the posterior). Therefore, based on the present study we sustain the monospecificinterpretation of the assemblage and reinforce the status of Rinconsaurus caudamirus as a valid species.