Huevos de Rhea pennata en el Holoceno Tardío de la provincia de Córdoba (Argentina): implicaciones ambientales, zoogeográficas y arqueológicas

Abstract

The recovery and identification of eggshell of Rhea pennata in the archaeological site Arroyo Talainín 2 (Cordoba Province, Argentina) dated between 1000-700 BP is reported. The current models of species distribution, the evolutive dynamics of the Sierra Chaco and the possible archaeological implications are discussed. The proportion of Rheidae eggshell respect to the whole faunal assemblage indicates that it was the main consumed animal resource. The presence of R. pennata in Cordoba is not covered by the distribution models for fossil and living Rheidae because the environments and paleoenvironments of the centre of Argentina are significantly different from the current habitat and the estimated past home of Rhea pennata. This forced us to rethink the chorological models, evaluating their biogeographic implications. Some new hypothesis are discussed as possible explanations: the potential ambiguity in the determinations, its representation as a relic of the Last Glacial Maximum, the coexistence of sympatric species, and the plains of La Rioja Province (Argentina) as a potential habitat and site of recollection of the eggs. The record of R. pennata in several archaeological and paleontological sites outside its current distribution area indicates that the geonemy of the species was larger in the past, including the mountains of Cordoba and/or surrounding plains. Consequently, the presence of R. americana would not be a warranty of sub-humid to semiarid conditions; neither R. pennata would necessarily indicate arid or semiarid conditions when small bounded areas are analyzed. Mountain environments would be «hot spots» in biogeographic parlance, in the Chaco monotony, with endemisms, «non-analogued associations», refuges and speciation «islands» with several elements that responded to the past and present biota.