UN ROEDOR CARDIATHERIINAE (HYDROCHOERIDAE) DE LA EDAD HUAYQUERIENSE (MIOCENO TARDIO) DE LA PAMPA. SUMARIO DE LOS AMBIENTES TERRESTRES EN LA ARGENTINA DURANTE EL MIOCENO

Abstract

ABSTRACT: A CARDIATHERIINAE RODENT (HYDROCHOERIDAE) OF HUAYQUERIAN AGE (LATE MIOCEN)FROM LA PAMPA,WITH A SUMMARY OF THE CONTINENTAL ARGENTlNIAN ENVIRONMENTS DURING THE MIOCENE. This is the first described articulated maxilla and mandible of a Cardiatherünae. They were found in La Pampa province, within sediments dated by other mammal remains as Huayquerian (Late Mioce .ie ), It is assigned to i the . o s Francis and Mones, 1965. Recent radioisotopic dates (K/ Ar) estimate the boundaries of the Huayquerian age between 9.0 and 5.0 million years B.P. The stratigraphical and structural evidence, along with fossil vertebrates, indicate that a long period of continental plains -mainly extended along the Argentinian territory situated to the North of the Nordpatagonian regionfollowed the Late Miocene Faraná-Entrerrían-Hionegran marine regression. Additionally, the data indicate two different kind of plains: flood plains and intermontane to low intramontane plains. The vertebrates coming from the flood plain sediments suggest lentic and lotic waters (e.g. crocodyles, turtles, fishes, hydrochoerid and dinomyid rodents). On the contrary, those coming from the occidental contemporaneous sediments suggest some eremic conditions (e.g. cavid and octodontid rodents). On the other hand, the isochronous vertebrates from the orthern Patagonian territory suggest more me sic climatic conditions (absence of crocodyles and presence of hydrochoerid rodents), with more temperate environments.