| Abstrakt: |
The Nahuel Huapi Region (North Patagonia, Argentina) preserves a rich paleontological and archaeological record of the last ca. 20,000 cal BP. This interval corresponds to the climatic fluctuations of the last part of the Late Pleistocene-Holocene period and a number of biotic events, including the megamammals extinction as well as the first arrival and expansion of Homo sapiens, which shaped the modern landscape and faunal communities. The mammals from this record contribute with information based on their isotopic composition (δ13C and δ15N) that allows to derive some preliminary inferences on paleoenvironmental changes during this crucial time-period. In this study, 15 new isotopic values and four new AMS ages are provided, including the first isotopic estimates of Megatherium americanumand Mylodontinae (Xenarthra, Folivora) from the Last Glacial Maximum in Patagonia. Isotopic information of these giant ground sloths is also compared with available values of the South America Southern Cone. Currently, Nahuel Huapi Region has one of the most marked West-to-East longitudinal gradients in the world. In δ13C values remain stable through the entire period, reflecting the predominance of C3plants. δ15N values show that the current climatic gradient was still not developed by ca. 20,000 cal BP ago. Mylodontinae rapidly colonized the West by ca. 13,500 cal BP, coping with climatic fluctuations. Drastic changes took afterwards, including the last appearance of megafauna and the first dispersal of Homo sapiensby 12,500 cal BP. δ15N values in the East section shows less abrupt changes. Holocene conditions were ameliorated, but the region still remained more open with shrubland’s patches, which contrasts with the nearby forested West. |
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