Site formation process and megamammal bone radiocarbon dates in Campo Laborde (Pampas of Argentina): Contribution towards a research methodology (original) (raw)
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Revista Mexicana de Ciencias Geológicas
A radiocarbon date (7550 ± 60 yr 14 C BP) was obtained from bone collagen of an extinct ground sloth (Scelidotherium leptocephalum) from the locality of Río Cuarto (Córdoba province, Argentina). The fossil remains were recovered from the La Invernada Formation (late Pleistocene-Holocene). The date presented in this paper is the first radiocarbon date obtained from megafauna in Córdoba province, Argentina. It supports the temporal assignation of the La Invernada Formation to the late Pleistocene-early Holocene, and it will allow correlation of these sediments with climatic events that took place during this time. Moreover, it is the youngest radiocarbon date from megamammals recorded in central Argentina.
The first AMS radiocarbon dates from the Camet Norte fossil site (Buenos Aires Province, Argentina) range from ca. 28,700 cal. BP to 27,500 cal. BP. The age of the site fits well with results of previous studies, but the more precise AMS radiocarbon dating allowed for a better determination of the site chronology, deposition and faunal attribution. It can be argued that the depositional environment of the site was not in proximity to the shoreline at the time of deposition based on palaeocoastline studies and the dates produced by this study.
Quaternary International 191, 2008
Investigations have been carried out at the Campo Laborde archaeological site in the Argentine Pampas. Some issues related to Pleistocene extinctions and the survivals of some species of megafauna into the Early Holocene are discussed. At the site of Campo Laborde, abundant bones of giant ground sloth (Megatherium americanum), some from other Pleistocene fauna (Doedicurus sp. and Neosclerocaliyptus sp.) and very few from extant fauna (e.g., vizcacha (Lagostomus maximus), Patagonian hare (Dolichotis patagonum), and peccary (Tayassu sp.), were found in association with two quartzite tools, 128 microlithic debris from different raw material and two informal bone tools. Each of the species is represented by only one individual and only one bone of M. americanum and one of D. patagonum show cut marks. Different lines of evidence suggest that Campo Laborde is a giant ground sloth procurement site on the border of an ancient swamp, where the prey was also initially butchered. One of the recovered tools is the stem of a broken bifacial projectile point, which would have been used as a hunting weapon. Based on the stratigraphic position, this site could date to the Early Holocene. Six AMS 14 C ages from M. americanum bone collagen, support this age although there is a wide chronological span between ca. 9700 and 6700 BP. The evidence obtained from Campo Laborde as well as from the La Moderna site indicates that some Pleistocene species such as giant ground sloth and some glyptodon (D. clavicaudatus and Neosclerocaliyptus sp.), survived in the Pampas until the Early Holocene. Therefore, these megafauna coexisted with early hunter-gatherers for several millennia and were exploited. r
Bone Diagenesis and Taphonomic History of the Paso Otero 1 Bone Bed, Pampas of Argentina
Samples of guanaco bone from an archaeological site in the Pampas of Argentina have been analysed to understand the diagenetic profile of the bone assemblages that characterized the taphonomic history of the site. Two archaeological occupations of Paso Otero 1 were investigated, encompassing similar landscape settings, climates, and depositional environments. The time span is a c. 2000 year period from c. 4800 to 2800 years . A total of 30 bone samples taken from both occupations were used to provide a preliminary characterization of the diagenetic pathways at the site. The parameters investigated provide a comprehensive account of how both mineral (hydroxyapatite) and bone protein (collagen) have been altered. In order to compare the two bone assemblages in terms of their diagenetic parameters, multivariate analyses were conducted. Results indicate two different diagenetic profiles in the site, % N being one of the variables that accounts for most of the variation in Paso Otero 1. The diagenetic analyses indicate that protein is less preserved in the bone assemblage from the middle stable landscape. Alternative interpretations of the diagenetic profiles are discussed in light of the taphonomic history of the site, and palaeoenvironmental information of the region. One hypothesis stresses the importance of the role of climate in defining the different diagenetic pathways, and the other the continued action of the combined diagenetic factors along time as the main explanation for the variability in the state of preservation of the bones in Paso Otero 1.
Late Pleistocene outcrops exposed in Buenos Aires province, Argentina, represent one of the most informative sources about the paleoecology of South American megafauna. However, there are no records of an accurately dated carnivoreeherbivore taphocenosis. This paper presents preliminary results of a recent excavation at the margins of the Salado River, on sediments attributed to the Luján Formation (Late PleistoceneeEarly Holocene). The fossiliferous strata consist of greenish brown sandyclays deposited in a small paleopond environment that was filled by fluvial sediments, exhibiting abundant organic matter, gypsum and carbonate concretions. Fieldwork yielded an association of extinct large-sized mammals that include the horse Hippidion principale, the saber-tooth cat Smilodon populator (at least one adult and one juvenile associated specimen), a giant ground sloth Megatherium americanum, and the glyptodont Doedicurus clavicaudatus. Four 14 C dates were performed on organic matter (12,100 AE 100 14 C BP), a femur of S. populator (13,400 AE 200 14 C BP), and a cervical vertebra of Hippidion principale (12,860 AE 120 14 C BP), and a pelvis of D. clavicaudatus (12,380 AE 190 14 C BP) situating the site within 12,500 and 13,500 years, approximately. Remarkably, some of the recovered specimens exhibit conspicuous bone modifications (furrows, pits, punctures, striations and crenulated margins) attributed to the activity of a medium-large carnivore. The association between bones of herbivore mammals with conspicuous modifications produced by a large carnivore, and the presence of cub and adult remains of Smilodon, link this felid with at least part of the excavated association.
In this work are presented the results of isotopic analyses made on bone remains of human individuals (n= 6) from the southern Puna of Argentina dated to the final Early Holocene (ca. 8230–8000 BP). They were found in structures located in Peñas de las Trampas 1.1, a rockshelter at 3582 m.a.s.l. in Antofagasta de la Sierra, in the southern Argentinian Puna. They contain multiple secondary burials. Bone fragments were recovered from at least six individuals, three in each structure. Stable isotopes of Carbon (δ13C) and Nitrogen (δ15N) analysis were aimed at defining aspects related to the palaeodiet of the six individuals within the palaeoeconomic subsistence spectrum typical of hunter–gatherers. It is worth noting that these human remains are among the earliest from North-Western Argentina, where funeral practices are related with the transportation of certain anatomical parts. The palaeodietary inference considers, on the one hand, the extreme aridity of this geographical area and its impact on the isotopic ecology. And, on the other, it takes into account the fact that four of the six individuals under study were breastfed infants. The results are in agreement with the expected values of the period, which has been characterized as the beginning of the arid Altithermal.