Reconstructing drowned terrestrial landscapes. Isotopic paleoecology of a late Pleistocene extinct faunal assemblage: Site GNL Quintero 1 (GNLQ1) (32° S, Central Chile)

Abstract

Site GNL Quintero 1 (GNLQ1), located nearshore at Quintero bay in the central coast of Chile (32° S), is the only documented Late Pleistocene drowned terrestrial site along the Pacific coast of South America. During the last decade, through underwater archaeological operations conducted at GNLQ1, several clusters of shallowly buried bone deposits were documented and excavated, revealing a well preserved high-resolution in situ context. Taxonomic analysis of the faunal assemblage recovered yielded at least 26 individuals comprising extinct Camelidae, Cervidae, Equidae, Mylodontidae, and Xenarthra as well as Canidae, Myocastoridae, Octodontidae, Cricetidae, among others. By conducting stable isotope analyses (δ13Cap and δ18Oap) on mammalian bioapatite, we aim to perform a first characterization of the GNLQ1 taxa paleoecology and carry out paleoenvironmental inferences. Regional records for the Last Glacial Maximum (LGM) suggest lower sea surface temperatures and more humid climatic conditions for Central Chile. Isotopic data obtained suggests a landscape of mixed vegetation areas, in good agreement with the sedimentary context of the fossil remains and a preliminary Quintero paleolandscape model: a wetland environment developed under semiarid conditions prior to post-glacial sea level rise, with GNLQ1 located >6 km inland as the paleoshoreline was further out on the continental shelf.