Neotaphonomy of a rodent skeletal accumulation by Strigiformes in an Andean valley. Implications for taphonomy, archaeology and palaeontology

Abstract

Holocene accumulations of rodent bones digested by raptors have been found in El Bolsón, a high-altitude valley in Catamarca, Argentina. Yet, so far there were no relevant taphonomic frames of reference to account for them. We thus studied a modern accumulation in Los Viscos rockshelter from a taphonomic perspective. The rockshelter is used for roosting, and the surface is covered by rodent skeletal remains. The analysed sample (NISP = 421) is dominated by remains of Phyllotis vaccarum, and also comprises other cricetid species, cavids, ctenomids and abrocomids. The anatomical, breakage and digestion patterns were compared to data on different predators. The most probable predator related to this accumulation is a Strigiformes (Aves) species. Most variables, including digestion, suggest a low-intensity modifier, probably Tyto alba, an individual of which was spotted around. Although Athene cunicularia may produce similar bone breakage, the prey taxa are not compatible with its diet. Alternatively, intense fragmentation may relate to postdepositional processes such as trampling. We discuss the implications of these findings for understanding the formation of the zooarchaeological and palaeontological record in the area, as well as for helping assess the global variability of Tyto alba taphonomic signature.