Environmental Stability During the Pleistocene-Holocene Transition in Northwestern Patagonia? The Small Mammals of Cueva Huenul 1 as Evidence

FERNANDO J. FERNÁNDEZ; ULYSES PARDIÑAS; PABLO TETA; RAMIRO BARBERENA

Current Research in the Pleistocene

Center for the Study of the First Americans

Año: 2011 vol. 28 p. 154 - 156

8755-898X

Recent excavations at Cueva Huenul 1 (CH1; 36°56’45”S, 69°47’32"W, 1008 m, Neuquén province, Argentina) yielded a rich sequence spanning the late Pleistocene-early Holocene, and reaching the late Holocene. In this note we briefly address the taphonomy and paleoenvironmental significance of the micromammal remains obtained in CH1.Fossil samples are dominated by silky desert mice Eligmodontia spp., leaf mouse Phyllotis spp., cavy Microcavia australis and tuco-tuco Ctenomys spp. Early Holocene and late Holocene assemblages are richer than the late Pleistocene ones and included two species typically associated with the Monte Desert, the sigmodontine Akodon iniscatus and the mouse opossum Thylamys pallidior, and the Patagonian rat Euneomys spp. (early Holocene). This situation, with the risk of a biased interpretation due to the small Pleistocene sample sizes, appears to be indicative of a smooth change towards a more heterogeneous environment since ca. 9500 RCYBP and up to the late Holocene, including a mosaic of shrubby steppes, open bare areas and large rocky outcrops. However, the basic signature (i.e., the codominance of Ctenomys spp., Eligmodontia spp., M. australis, and Phyllotis spp.) of the small mammal assemblages of CH1 remained almost without changes during the Pleistocene-Holocene transition, even up to the late Holocene. Few kilometers west of this cave a recent owl pellet sample shows the occurrence of several abrotrichines (Abrothrix longipilis, A. olivaceus) and high proportions of Euneomys and Reithrodon auritus under cooler and wetter conditions. This faunal assemblage never reached CH1 vicinities, in accordance with the preserved record, an expectable situation if cooling events had occurred, suggesting a remarkable ecological resilience to climate change. The general faunal stability of CH1 is in agreement with the environmental stability inferred on the basis of pollen data from the segment 14,800-8,900 RCYBP of Mallín Vaca Lauquen. Additionally, small mammals of CH1 do not reflect the occurrence of the Huelmo/Mascardi Cold Reversal.