Micromammals and paleoenvironments: Climatic oscillations in the Monte desert of Catamarca (Argentina) during the last two millenia

Abstract

The understanding of the Holocene climatic fluctuations through the study of micromammal sequences can help to know the current environmental dynamic in arid lands. This is relevant because of the accelerated transformation that these environments are undergoing. We report the first stratified micromammal assemblage from the Monte desert on Northwestern Argentina, which span the last two millennia. We studied 11 700 cranial remains accumulated by owls’s trophic activities, representing 16 species (MNI = 5031). The assemblage composition is consistent with the species found in the area today, being the dominant Phyllotis xanthopygus, Eligmodontia spp., and Calomys musculinus. Relative frequencies and diversity show slight variations throughout the sequence, suggesting environmental stability. However, minor changes for several species indicate small-scale variations. We infer climatic conditions similar to those of the present for the period of 1600–1300 yBP, wetter conditions for 1000–600 yBP, and a return to xeric conditions up until the present. This reconstruction agrees with previous interpretations regarding global climatic dynamics, as those involving the Medieval Warm Period and the Little Ice Age. Since there are no areas potentially affected by agricultural activities within the owl’s hunting area, the fluctuations are interpreted as primarily the result of changes in climatic conditions.