REDIAGNOSIS OF RINCONSAURUS CAUDAMIRUS CALVO AND GONZÁLEZ RIGA (DINOSAURIA, SAUROPODA) FROM THE ANACLETO FORMATION (UPPER CRETACEOUS: CAMPANIAN) OF RINCÓN DE LOS SAUCES (NEUQUÉN, ARGENTINA)

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

Puerto Madryn

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2018

Despite its great diversity, knowledge of many aspects of titanosaur sauropod anatomy is relatively poor, in part due to the fragmentary nature ofmany 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 its original description, this taxon has not been subjected toan exhaustive revision, which has raised a number of questions about its taxonomical status. Among them, stand out the fact that characters 1 and2 from the three originally used for diagnosing it showed to be more widespread distributed among Titanosauria. Additionally, an importantmorphological variability is observed among caudal vertebrae, making necessary the revision of the assemblage originally stated out. Here wepresent a revision of the postcranial material of Rinconsaurus based on new observations and comparisons with related taxa. Theobserved morphological differences in caudal vertebrae could be well explained as the product of different ontogenetic stages and serialvariations, whereas three new autapomorphic character were detected (1-posterior cervicals with the ventral end of the spinoprezygapohyseallamina intercepting the intraprezygapophyseal lamina; 2-anteriormost caudals with two marked lateral faces with the lower face stronglyconstricted ventrally; 3-caudal vertebrae with the anterior articular surface markedly higher than the posterior). Therefore, based on the presentstudy we sustain the monospecific interpretation of the assemblage and reinforce the status of Rinconsaurus caudamirus as a valid species.