On the validity of the Macrochorobates scalabrinii Biozone (early Huayquerian Stage/Age, Late Miocene). Multi-proxy analysis of the enigmatic Arenas Blancas site (Buenos Aires Province, Argentina)

Arenas Blancas is a poorly known fossiliferous site located in the lower reach of Chasicó creek (Buenos Aires Province, Argentina), with great relevance from biostratigraphic viewpoint. The Macrochorobates scalabrinii Biozone was defined this site, proposed as basis early Huayquerian Stage/Age (Late Miocene); however, geological context and faunal record have never been studied detail. In work, we perform multi-proxy analysis well nearby here called Curva de la Vaca, provide new interpretations on their origin, age, biostratigraphy. Sedimentological, stratigraphic, geomorphological characteristics both sites suggest that sequences include fluvial/alluvial deposits represent Quaternary terraces. taxonomic assemblage evidences presence 14 mammal taxa, together some fishes, reptiles, birds; correlated Cerro Azul Formation assigned to Chasicoan Miocene), also recovered creek. use taxa previous works characterize (including species) not supported due status and/or temporal distribution. Taphonomic evaluation indicates constituted by reworked specimens; frame, it fluvio/alluvial events, occurred during Late Pleistocene-Holocene, eroded Upper Miocene substrate fossil remains. Based present evidence, rejected valid unit.