Local extinctions in the small mammal's assemblages between late Holocene and historical times in Talagapa mountains (Patagonia, Argentina): The role of land use changes

Abstract

The aim of this work was to evaluate possible changes in the small mammal composition in the Patagonian arid Extra-Andean steppes between the late Holocene and historical times. A bone sequence accumulated by the disintegration of owl pellets deposited inside a cave in the Talagapa mountains (Chubut province, Argentina) was analyzed. The paleontological sequence encompasses a time span since 2.857 ± 50 years BP and 2.285 ± 40 years BP and was covered by a thick and compact layer of sheep feces that set the boundaries of historical times. Rodent prey were identified and quantified on the basis of skulls and mandible pairs and Holocene and historical assemblages were compared with those recovered from modern owl pellets collected in the area. The sharpest change appears in recent times, after the modification in the land use in the area, with local extinction of Loxodontomys micropus, a species associated with mesic habitats, and the apparent modification in the frequencies of certain species. Hypotheses about climatic, anthropic, and environmental factors that may have influenced those variations are discussed.