Andrés Darío Izeta

Holocene (~4.5–1.7 cal. kyr BP) paleoenvironmental conditions in central Argentina inferred from entire-shell and intra-shell stable isotope composition of terrestrial gastropods

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.

A Fishtail Projectile Point from the Southern Pampean Hills, Characato, Córdoba, Argentina

Here we report a newly discovered Fishtail projectile point, or Fell 1 projectile-point type, from Characato valley in the southern Pampean Hills of central Argentina. It is a fluted basal stem fragment on a non-local dark red volcanic rock. Fishtail points are rare, and archaeological sites dating to the Pleistocene-Holocene transition particularly scarce, in this region; hence, this new evidence importantly establishes early human occupation through material culture.

Isótopos estables, dieta de camélidos y diferenciación social (valle de ambato, Catamarca, Argentina, siglos VI-XI D.C.)

En este trabajo se discute el modo en que se organizo la produccion ganadera en el Valle de Ambato, Catamarca, entre los siglos VI y XI d.C., a partir de nuevos analisis isotopicos de δ13C realizados sobre restos de camelidos. Los resultados alcanzados, sumados a los obtenidos previamente en otros trabajos, permiten plantear la existencia de dos formas de sustento de los camelidos: una de movilidad extensa y alimentacion muy variada vs. otra de movilidad restringida y alimentacion controlada. Esta ultima habria sido uno de los elementos fundamentales que habria conformado un sistema de produccion agropastoril integrado, que articulaba la cria de plantas y camelidos en un mismo espacio y con una misma infraestructura.