NEW SAUROPOD INFORMATION FROM ?VALLE DE LOS TITANOS? SITE, CAMPANIAN (UPPER CRETACEOUS), NEUQUÉN BASIN, PATAGONIA, ARGENTINA

BELLARDINI, FLAVIO; WINDHOLZ, GUILLERMO J.; BAIANO, MATTIA A.; LECUONA, AGUSTINA; POL, D.

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Jornada; III Jornadas de Paleontología de la Cuenca Neuquina; 2021

The fieldworks carried out by an italo-argentinian paleontological team to the ?Valle de los Titanos?(General Roca, Río Negro Province, Argentina) discovered several fossiliferous sites in the fluvialoutcrops that we preliminarily refer to the lower section of Allen Formation (Campanian). From2005 to 2010, more than five hundred sauropod bones were recovered from a single fossiliferouslayer and housed in the Museo Patagónico de Ciencias Naturales of General Roca. Our preliminaryosteological examination of the material from the site ?G? and ?L?, two quarries at 150 meters aparteach other, allows us to recognize cranial, axial, and appendicular elements of several titanosaurianspecimens at different ontogenetic stages. The caudal vertebrae are procoelic and high pneumatized,like seen in Rocasaurus, but lack of the longitudinal septum on ventral surfaces. The scapula MPCNPV-407 from the site ?G have a quadrangular acromion process and a posteriorly unexpanded shaft;anteroventrally, the glenoid is medially beveled and strongly ventrally expanded, forming aprominent process, which is absent in the scapula MPCN-PV-243.45 from site ?L? and in any othersauropod known. A fibula from site ?G? (MCPC-PV-242.1) bears a mediodistal fossa, as inSaltasaurus, but it is absent in a fibula from site ?L? (MPCN-PV-243.85). This preliminary analysissuggests the co-existence of at least two titanosaurian morphotypes in the ?Valle de los Titanos?area. Further comparisons with the others titanosaurian taxa from the Allen Formation will allow usto elucidate the composition of the sauropod fauna in the southeast Neuquén Basin during themiddle-late Campanian.