The rheids as palaeoenvironmental and consumption indicators during the latest Pleistocene and the middle Holocene

Abstract

The record of flighless birds of the Rheidae Family is frequent but usually scarce in the archaeofaunal contexts in Patagonia (Southern South America). In this sense, the Deseado Massif area is a particular example, since the rheids are present from the very earliest occupations, though with variations in number and species represented. The register of the Greater rhea (Rhea americana) associated to herbivorous mammals (Hippidion saldiasi, Lama gracilis) that extinguished between 15,000 and 12,500 cal years BP, and sharing the ecospace with the Lesser rhea (Rhea pennata) drew our attention about changing environmental conditions during the latest Pleistocene and Early Holocene. The discontinuity and fragmentation in the record up to now did not let to confirm when the abandonment and replacement of flightless birds occurred until the findings in two archaeological localities in southern Patagonia, where Rhea americana were registered. In archaeological contexts, the bone records of the rheid species are usually scarce; contrarily, fragments of eggshell are much more frequent. The rheid bones studied in this contribution come from the Lower and Upper components of AEP-1 site. With the aim of discussing the presence of rheids in the archaeofaunal assemblages, we analyze the records from taxonomic, anatomic, taphonomic and paleoenvironmental point of view under a qualitative-quantitative methodology. Besides the archaeofaunal data, the representation of these birds in the rock art, ethnohistorical and ethnographic information were analyzed in order to comprehend the human-flightless birds? interactions during the Late Pleistocene-Holocene transition and Middle Holocene, as well as the role played by these birds in the economic, social and symbolic spheres among the hunter-gatherer societies. Phalanges are usually the skeletal piece best represented. The case of AEP-1 site points an exception to both contexts, the Lower Component (13,000 - 10,500 cal years BP) where the NISP of Rhea cf. americana is higher than the NISP of Rhea pennata and the Upper Component (8600- 7900 cal years BP) where only Rhea pennata was identified. The high frequency of rheids along time in Piedra Museo Locality is interpreted under the hypothesis of a kill and processing site where the hunting and consumption of "ñandúes" took place together with guanacos. Therefore, the presence of Rhea cf. americana in the earliest occupations is taken as a marker of environmental changes.