Palimpsest of micromammal deposits in an archaeological rock shelter (Alvarez 4, Late Holocene) from northwestern Patagonia, Argentina

This study provides a taphonomic and paleoenvironmental analysis of the micromammal (<1 kg) accumulations from the archaeological site Alvarez 4 (AZ4), a rock shelter located at the middle basin of the Limay River, Rio Negro Province, northwestern Patagonia, Argentina. Based on taphonomic and taxonomic features, several skeletal remains accumulated in Period I (963 cal. BP), Period II (187 cal. BP), and square C3 (963 cal. BP) are assigned to the action of Strigiformes, while pellets found in the surface layer (SL) (187 cal. BP) would have been deposited by Accipitriformes. Pellet bones were more protected from trampling than bones recovered from the sieved sediments of the SL. In addition, some Caviidae remains from Period II and square C3 were likely incorporated in human consumption. This low-ranked resource might have complemented the otherwise high-ranked animals found in Alvarez 4, which would suggest a similar diet breadth to that frequently seen at several archaeological sites in the area. The paleoenvironmental analysis based on the small mammals recovered from AZ4 shows the development of open areas of shrubby-grassy Patagonian steppe and large rocky outcrops with overall stability of habitats, with a dominance of shrublands and steppes in the last similar to 1000 years. Past environments were more heterogeneous than today, as evidenced by the absence of some species and the expansion of opportunistic species in the modern pellet samples near to the rock shelter.