Holocene distribution of caviids and ctenomyids rodents in the north Patagonian Andean forests: paleoenvironmental and paleoecological relevance

Abstract

This paper discusses the implications of the presence of caviid and ctenomyid (Caviomorpha) species in northwestern Patagonian Andean forests during the Holocene, extralimital to their current distributional area. Small mammal cranial remains (NISP = 11284, MNI = 1822) from Población Anticura archaeological site were studied (41°36´S-71°31´W, lower Manso River valley, Río Negro Province, Argentina). The remains were recovered from archaeological units ranging from the Early Holocene to Historical times (9168?293 calibrated years before the present). The Holocene assemblages ?species from wooded and ecotonal shrubland areas associated with Monte and Patagonian steppes elements like Caviomorpha ? have no modern analogue. It is proposed that these Caviomorpha species would have inhabited the area since the Pleistocene?Holocene transition, when the retreat of the glaciers allowed the gradual advance of forest over steppe in the valley and the development of open forest/shrubland on the eastern flanks of the Andes. Forest clearings, both natural and anthropogenic, likely maintained populations of caviids, ctenomyids and the ecotonal grassland/steppe specialist Reithrodon auritus, in the valley throughout much of the Holocene. Their subsequent extinction in these forests is likely attributable to anthropogenic causes.