Abstract:

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.

Author affiliation: Cotte, Martin. Universitat Tübingen; Alemania

Author affiliation: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina

Author affiliation: Hajdas, Irka. Swiss Federal Institute of Technology Zurich; Suiza

Author affiliation: Straccia, Pablo. Provincia de Buenos Aires. Municipio de Santa Clara del Mar. Museo Municipal de Ciencias Naturales Pachamama; Argentina. Universidad Nacional de Mar del Plata; Argentina

Author affiliation: Scian, Daniel. Provincia de Buenos Aires. Municipio de Santa Clara del Mar. Museo Municipal de Ciencias Naturales Pachamama; Argentina

Author affiliation: Soibelzon, Leopoldo Héctor. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Bocherens, Hervé. Universitat Tübingen; Alemania

Abstract:

The diet of extinct giant Xenarthrans is a debated topic, especially for ground sloths, for which herbivory, insectivory, and carnivory through scavenging or active hunting have been suggested. In this study, stable carbon isotopic composition of collagen and carbonate fraction of well-preserved fossil bones was used as a tracer of trophic level. > 200 modern mammal bones of species with a variety of diets were used as a reference dataset. The good preservation of the carbonate isotopic composition was checked using different diagenetic indicators and by using fossil carnivorous and herbivorous taxa from the same sites as test-taxa. The results on modern mammals indicate a clear distinction in the difference between the carbon isotopic composition of carbonate and collagen between faunivores (carnivores, insectivores, piscivores, omnivores) and herbivores. Using this framework, the results on the fossil megafaunal Xenarthrans indicate a herbivorous diet for both Glyptodontids and are also consistent with a herbivorous diet for giant ground sloths, including Megatherium. The hypothesis that Megatherium could be a cryptic meat-eater or an insectivore is not supported by the results obtained in the present study.

Author affiliation: Bocherens, Hervé. University of Tübingen; Alemania

Author affiliation: Cotte, Martin. University of Tübingen; Alemania

Author affiliation: Bonini, Ricardo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Investigaciones Arqueológicas y Paleontológicas del Cuaternario Pampeano; Argentina

Author affiliation: Straccia, Pablo. Municipio de Mar Chiquita. Museo Municipal de Ciencias Naturales Pachamama; Argentina. Universidad Nacional de Mar del Plata; Argentina

Author affiliation: Scian, Daniel. Municipio de Mar Chiquita. Museo Municipal de Ciencias Naturales Pachamama; Argentina

Author affiliation: Soibelzon, Leopoldo Héctor. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina

Abstract:

The sabretooth cat Smilodon populator was the largest felid in South America. It appears in the fossil record in the Early Pleistocene, as an immigrant from North America, and becomes extinct around the Pleistocene–Holocene boundary. The carbon and nitrogen stable isotopic values of collagen were measured for skeletal remains from Smilodon specimens ranging in age from 25 to 10 kyr BP, for the first time in the Pampas region of Argentina. By comparison with similar values obtained on co-eval predators such as Protocyon (large canid) and Panthera onca (jaguar) and a range of potential prey, such as giant ground sloths, glyptodontids, Macrauchenia, Toxodon, equids, cervids, and rodents, it could be established that Smilodon consumed essentially large prey from open landscape, such as Macrauchenia and giant ground sloths during the last 15,000 years of the Late Pleistocene in the Pampa region. It was possibly competing with the large canid Protocyon but the jaguar was apparently feeding on smaller size prey. A more humid climate at the beginning of the Holocene might have been unfavorable to this large predator and could have contributed to its extinction. These results also provide an important insight to understand the ecological processes involved in the Great American Biotic Interchange.

Author affiliation: Bocherens, Hervé. University of Tübingen; Alemania

Author affiliation: Cotte, Martin. University of Tübingen; Alemania

Author affiliation: Bonini, Ricardo Adolfo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Scian, Daniel. Municipio de Mar Chiquita. Museo Municipal de Ciencias Naturales Pachamama; Argentina

Author affiliation: Straccia, Pablo. Municipio de Mar Chiquita. Museo Municipal de Ciencias Naturales Pachamama; Argentina. Universidad Nacional de Mar del Plata; Argentina

Author affiliation: Soibelzon, Leopoldo Héctor. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina