Amidst wind, sand and raptors. Small mammal bone remains recovered in open-air archaeological sites from the Monte Desert in Central Western Argentina: taphonomic and palaeoenvironmental implications

The distinctive characteristic of the Monte Desert, the most arid range land of Argentina, is reflected in the varied composition of its small mammal fauna. The present study analyses the taphonomic features and the palaeoenvironmental implications of small mammal bone and tooth accumulations recovered in open-air archaeological sites from the Monte Desert plains of northern Mendoza (Central Western Argentina) in the South American arid diagonal. In order to identify the agents responsible for such accumulations relative abundance trends, bone breakage patterns and digestive corrosion were evaluated. The action of postdepositional processes, like weathering and trampling, also were analysed. Taphonomic results allowed the detection of avian raptors-owls in particular-as the principal accumulating agents of small mammal bone and tooth accumulations of open-air archaeological sites from the Monte Desert. In order to make palaeoenvironmental inferences, the taxonomic structure of archaeological and modern small mammal assemblages was analysed and compared, added to the evaluation of taphonomic dynamics in the archaeological sites. The taxonomic composition of archaeological assemblages differed from that of the current assemblages from the study area. Thus, an extinct species (Holochilus lagigliai) and a little-known species highly adapted to desert environments (Tympanoctomys barrerae) were detected in the archaeological record. Recent pellet samples showed major proportions of opportunistic and generalist species as well as the presence of an exotic species (Mus musculus). The general impoverishment of current small mammal assemblages in comparison with past ones (e.g. richness, diversity and evenness) could be attributed to the deep impact of the anthropic perturbations generated by economic activities since the arrival of European conquerors ca. 500 years BP. Small mammal archaeological assemblages could indicate a scenario of greater environmental heterogeneity during the Late Holocene than in the present, and thus, greater availability of patch resources in the landscape.