Small mammals from the Late-Holocene of the archaeological locality Casa de Piedra de Roselló (southwest Chubut Province Argentina) and their paleoenvironmental implications

The integration of zooarchaeological and palaeoenvironmental studies enables the evaluation of species distribution and abundance patterns in relation to climatic and environmental fluctuations through time. This study analyses rodent composition from modern Barn owl pellets (MNI = 138) and archaeological samples (MNI = 58) from the Casa de Piedra de Roselló (CP) archaeological locality (Central Patagonia), with the aim of assessing possible changes in species representation between the Late-Holocene and the present day. CP is located within the forest-steppe ecotone and features a long occupation sequence, ranging from ca. 9000 cal BP to historical times. For the final stages of the Holocene, the species Abrothrix hirta , A . olivacea , Ctenomys sp., Euneomys chinchilloides , Geoxus sp., Loxodontomys micropus , Microcavia australis , Paynomys macronyx , and Reithrodon auritus were recorded. Except for E . chinchilloides , these species are characteristic of ecotonal forest-steppe environments. E . chinchilloides remained the dominant species while A . olivacea increased at present and forest-associated taxa such as Geoxus sp ., and P . macronyx decreased or disappeared. The proportion of Reithrodon auritus was also significantly higher in the archaeological sample compared with the current sample. Eligmodontia sp., Oligoryzomys longicaudatus and Phyllotis xanthopygus are exclusive from the modern sample. Rather than reflecting a major environmental transformation, both rodents’ assemblages point to a predominantly semi-arid and open landscape, characterized by a substantial proportion of bare ground. At a finer micro-environmental scale, these changes in species composition suggest environmental shifts, from greater availability and extension of turf ( mallin ) and grassy steppes in the final Late-Holocene to increased shrub expansion in recent times. Changes may be likely linked to post-Hispanic extensive livestock farming and overgrazing in the area.