María A. Gutiérrez

The Arrival of Homo sapiens into the Southern Cone at 14,000 Years Ago

The Arroyo Seco 2 site contains a rich archaeological record, exceptional for South America, to explain the expansion of Homo sapiens into the Americas and their interaction with extinct Pleistocene mammals. The following paper provides a detailed overview of material remains found in the earliest cultural episodes at this multi-component site, dated between ca. 12,170 14C yrs B.P. (ca. 14,064 cal yrs B.P.) and 11,180 14C yrs B.P. (ca. 13,068 cal yrs B.P.). Evidence of early occupations includes the presence of lithic tools, a concentration of Pleistocene species remains, human-induced fractured animal bones, and a selection of skeletal parts of extinct fauna. The occurrence of hunter-gatherers in the Southern Cone at ca. 14,000 cal yrs B.P. is added to the growing list of American sites that indicate a human occupation earlier than the Clovis dispersal episode, but posterior to the onset of the deglaciation of the Last Glacial Maximum (LGM) in the North America.

Análisis Comparativo de los Patrones de Modificaciones Óseas de Dos Carnívoros Sudamericanos: El Gato Montés (Leopardus Geoffroyi) y el Zorro Pampeano (Lycalopex Gymnocercus). Aportes para la Identificación de la Acción de Pequeños Carnívoros en el Registro Arqueológico

RESUMENEl objetivo de este trabajo es caracterizar y comparar los patrones de modificaciones oseas producidos por dos carnivoros autoctonos de Sudamerica, el zorro pampeano y el gato montes, sobre partes esqueletarias de pequenos vertebrados. Para esto se realizo una experiencia en un parque zoologico local, ofreciendo 10 conejos en forma controlada, a cada uno de los predadores mencionados. En esta oportunidad se presentan los resultados de los restos no ingeridos, para los cuales se analizo la representacion anatomica y los patrones de fractura. Los resultados indican que tanto el gato montes como el zorro pampeano generan una destruccion osea significativa en los restos de conejo, lo cual impacta directamente en la representacion de los individuos. Los elementos con mayor supervivencia fueron los huesos largos, la pelvis, el craneo y la mandibula. Por otra parte, la densidad osea resulto ser uno de los factores que condiciono la destruccion diferencial de los elementos. Si bien nuestros resultados no permiten diferenciar las modificaciones generadas por estas dos especies de carnivoros, los patrones observados aportan nuevos datos que ayudan a distinguir estos conjuntos de aquellos originados por otros predadores como por ejemplo, aves rapaces diurnas y nocturnas. PALABRAS CLAVE: tafonomia experimental, gato montes, zorro pampeano, pequenos vertebrados, modificaciones oseas.COMPARATIVE ANALYSIS OF BONE MODIFICATION PATTERNS PRODUCED BY TWO SOUTH AMERICAN CARNIVORES: THE GEOFFROY’S CAT (

Estudio comparativo de las marcas de dientes producidas por dos pequeños carnívoros sudamericanos

En este trabajo se presentan los primeros resultados de un estudio experimental realizado con zorro pampeano (Lycalopex gymnocercus) y gato montes (Leopardus geoffroyi) con el fin de caracterizar el patron de marcas de dientes generado por cada carnivoro sobre restos oseos no ingeridos de un mamifero pequeno y evaluar si existen diferencias en estos patrones. Este estudio indico que ambos carnivoros generan los mismos tipos de modificaciones y en proporciones similares; no obstante, el numero promedio de marcas por especimen es mas del doble en el caso del zorro. Sobre la base de los resultados preliminares obtenidos se propone que el tamano de los hoyuelos no parece ser un criterio diagnostico determinante para distinguir la accion de estos dos predadores.

Taphonomy of modern communal burrow systems of the Plains vizcacha (Lagostomus maximus, Chinchillidae) in the Pampas region of Argentina: implications for the fossil record

Abstract The Plains vizcacha (Lagostomus maximus) is one of the largest rodents in South America. They live in communal burrow systems (vizcacheras) shaped by complex subterranean galleries which produce a strong impact on the local landscape. This paper presents the results of an actualistic study conducted with abandoned vizcacheras from the Pampas region of Argentina. The main objective is to evaluate the role of this rodent in the formation of the fossil record. Results indicate that the Plains vizcacha is responsible for the mixing, accumulation, and transport of materials; such as sticks, caliche, dung, feces, and abundant bone remains. Their burrowing activity and the accumulating habits, modifies the landscape, creating environments conducive to the buildup of objects and the reuse by different animals. These characteristics result in very complex associations of materials of different origins; making this rodent an important taphonomic agent with the potential to significantly impact the fossil record.

Exploration of diagenetic profiles at mammoth localities on the North American grasslands

As a feasibility study, samples of mammoth bone from four localities across the North American grasslands were analyzed to assess preservation and provide an initial overview of the diagenetic history at each of the different sites. The localities encompassed different landscape settings, climates, and environments from the period ca. 12,300 to 11,100 yr BP (uncalibrated radio- carbon years). A small sample size of 12 bones (three from each locality) was used to provide a preliminary characterization of the diagenetic processes and resulting preservation at each locality. Results indicated two different diagenetic profiles, a Northern Profile and a Southern Profile. Bones from the Northern Profile were well preserved for samples of this age. Little or no alteration was observed in the histological structure, nor in the collagen or mineral phases. Total porosity values, however, ranged from fresh bone values to increases of three times that of fresh cow bone. Bones from the Southern Profile generally were poorly preserved. Mineral and collagen phases had experienced significant diagenetic alteration and total porosity increases are consistent at around two to three times that of fresh bone values. These samples exhibited minimal histological alteration, however, and, in general, their histological structure is better preserved than samples from the Northern Profile. Based on extensive sedimentological studies, the dominant hydrologic regimes at each locality not only shaped the landscape, but also appeared to have played a decisive role in determining the diagenetic histories of the buried mammoth remains. Preliminary results strongly supported the importance of groundwater activity (i. e., presence, absence, and fluctuations) throughout the period of burial in the preservation of the skeletal remains.

Early Holocene water well in the Pampas of Argentina: Human responses to water shortage events

Water wells are ethnographically and archaeologically described in Australia and the plains of North America. Recently, a prehistoric water well from the early Holocene was recorded in the Pampas of Argentina. The aim of this paper is to present the main characteristics of the water well, considering its form, dimension, sediment analyses (texture and chemical parameters), and material culture content. This is the first water well recorded in the Pampas of Argentina. Consequently, a discussion about natural or cultural origins of this kind of features is provided. An evaluation of similarities and differences with well-described water wells from the United States and Australia is included in order to highlight the cultural origin of the pit. Also, the meaning of the cultural response to water availability in terms of early-Holocene hunter–gatherer adaptations as well as the implications of this strategy for understanding paleoenvironmental scenarios of the Pampas of Argentina are discussed. The well seems to have mitigated an exceptional lack of surface water in the eastern Pampas or offered an alternative for the non-drinkable quality of the available surface water. The strategy of digging water wells was available in the behavioral repertoire of the Pampean hunter–gatherer populations as early as c. 8700–8000 14C yr BP (c. 9700–8800 cal. yr BP), as these groups were fairly flexible and resilient in dealing with short-term shortages of water.