Late Cenozoic mammals from the Northwest of Argentina

REGUERO AND CANDELA

Cenozoic Geology of the Central Andes of Argentina

INSTITUTO DEL CENOZOICO (INCE)

Año: 2011; p. 411 - 426

The biostratigraphy and biogeography of late Miocene mammals throughout Northwest (NW) Argentina is reviewed and discussed. FADs (first appearance data) of the earliest immigrants to South America (Carnivora, Procyonidae) were used to get a reliable temporal ordination of the late Miocene faunas from NW Argentina. Results from this analysis are generally consistent with the faunal sequence of stages and zones which was primarily established with faunas from the Atlantic Coast. Exception is a fauna from La Rioja province (Toro Negro Formation) that shows misalignment due to high degrees of endemism and no record of immigrants. Comparison of late Miocene mammalian faunas at the generic level indicate that: i) the differentiation in faunal similarity and composition between Northwest, Northeast and Atlantic Coast areas started near the middle Miocene-late Miocene boundary; ii) this differentiation is reflected by the appearance of the first Holarctic immigrants of the pre GABI (Great American Biotic Interchange); iii) in Northwestern Argentina, faunal endemism increased in the late Miocene, and iv) the boundary between Huayquerian and Montehermosan stages can be established by the FAD of a taxon belonging to a holarctic group (Procyonidae). The classical late Miocene continental faunistic sequence of Chiquimil-Puerta Corral Quemado, Catamarca, NW Argentina containing Huayquerian and Montehermosan faunas in superposition have produced both radioisotopic and lengthy mangnetostratigraphies spanning continuously approximately from Chron C4An to Chron C2Ar, between 9 Ma and 3.2 Ma. Keywords: biostratigraphy - biogeography - Miocene-Pliocene - mammals - Northwest of Argentina