No abstract

Stable isotope analysis has been used in archaeology to answer a variety of questions. In general, the study of human palaeodiets has been the main subject. Studies of past animal feeding behaviour have not been considered extensively in South America. In this paper we discuss the interpretation of the d 13 C values in camelid bone specimens on the basis of published and new data from the southern Andes (northwestern Argentina). The temporal frame is mainly focused in the first millennium AD (part of the local Formative Period -400 BC to 600 AD -as well as the Regional Integration Period at 600-1000 AD, and the Late Period at 1000-1500 AD) which for this area implies a time of great social changes. Samples from modern Camelidae family were used to compare with those from archaeological sites, interpreting two different patterns that can be associated with distinctive animal feeding strategies. We suggest that these strategies can be associated with human management rather than free-range camelid feeding behaviour. Thus stable isotopes become an innovative strategy to segregate domestic from wild camelids, complementing those results achieved by osteometric and statistical analyses. Moreover, they allow for camelid management interpretation in three different localities of the area from the above-mentioned different periods.

The isotopic fingerprint of terrestrial gastropods has been increasingly used as a credible natural paleoenvironmental archive. Most published work has used this proxy at tropical and temperate latitudes of the Northern Hemisphere, and focused on entire-shell analysis. The present study provides entire-shell and intra-shell isotopic profiles to infer average and seasonal late Holocene environmental conditions in central Argentina (30°S). Shells of Plagiodontes daedaleus (Gastropoda: Odontostomidae) were retrieved from the Alero Deodoro Roca–Sector B site, one of the few archaeological sites in central Argentina rich in shells collected by pre-Hispanic hunter-gatherer groups. Ancient entire shells exhibited values that were ~2.5‰ higher in δ13C and ~1.8‰ higher in δ18O than modern individuals, pointing to higher abundance of C4 plants and overall drier conditions (lower relative humidity and/or higher rain δ18O) during 4.5–1.7 cal. kyr BP than today, in agreement with published regional proxies. Intra-shell isotopic profiles suggest that modern and fossil specimens deposited their shells throughout two-to-three summer/winter cycles. Intra-shell δ18O values varied ~5‰, matching with the seasonal variation of rain δ18O values. The extent of seasonality was similar during 4.5–1.7 cal. kyr BP and today. Intra-shell δ13C values varied ~2–3‰ and did not portray distinct seasonal cycles, depicting minimal seasonal variations in the snail diet. This work illustrates that South American terrestrial gastropods have great potential for paleoenvironmental studies.