Vertebrates from the Late Miocene of Salinas Grandes de Hidalgo (central Argentina)

Abstract

Salinas Grandes de Hidalgo (La Pampa Province) is a relevant locality of the Cerro Azul Formation in central Argentina because of its abundant and diverse vertebrate remains, including representatives of Reptilia, Aves and mostly Mammalia. Concerning previous records, the present faunal list adds one Argyrolagidae marsupial, one Ctenomyidae and two Caviidae rodents, as well as the first detailed analysis and description of glyptodonts from the Cerro Azul Formation in La Pampa Province. Also, in the context of this formation, this fossiliferous area presents the highest faunal richness. New geological information is added about the two fossiliferous outcrops included in Salinas Grandes de Hidalgo area. The classically studied outcrop located in the saline lake and the nearby one in the so-called ex-Autódromo, both herein correlated based on lithostratigraphy, particularly by the presence of paleosols in the intermediate section of the sedimentary succession. These sandy silts deposits indicate the development of poorly confined flows and intervals of surface stabilization by pedogenesis. We offer a biochronological interpretation based on a recently published U-Pb detrital zircons dating (5.9 ± 0.4 Ma) and the presence of significant taxa such as octodontoid rodents recovered from the dated level and below them. From a paleoenvironmental viewpoint, we infer variations from woodlands to open environments.