First evidence of an underwater Final Pleistocene terrestrial extinct faunal bone assemblage from Central Chile (South America): Taxonomic and taphonomic analyses

摘要

Site GNL Quintero 1 (GNLQ1), located in Quintero Bay (32°S, Central Chile) constitutes the first evidence of a drowned terrestrial site on the continental West Coast of South America covered by sea-level rise after the Last Glacial Maximum. The site currently lies 650 m offshore and 13 m underwater, covers an area of ～ 64 m~2 and contains several discrete exposed and shallow-buried bone deposits. Through underwater archaeology survey and test excavations, a significant amount of animal bone assigned to the Late Pleistocene was successfully recovered and analyzed. After recovery and prior to the analyses, the bones were subjected to conservation and stabilization treatments, resulting in good preservation of the material. Taxonomic analyses (NISP 224) revealed high taxonomic diversity of extinct fauna (Camelidae, Cervidae, Artiodactyla, Equidae, Mylodontidae, Canidae, Rodentia and Xenarthra). The sample represents a continental faunal assemblage belonging to a drowned terrestrial context, probably related to an estuarine-lagoon environment. Taphonomic analysis allowed macroscopic identification of natural marks (punctures) associated with large and small size carnivores. The bones also show abrasion related to the action of marine sands along with colour alterations. By applying Scanning Electron Microscope (SEM) micrographs and Energy-Dispersive Spectroscopy (EDS) to fossil bones, marks and colour alterations were identified. Marks indicated rodent gnawing and trampling, while colour alterations were attributed to diagenesis processes, discarding thermal treatment. Site GNLQ1 is identified as having very high potential, for it provides the first evidence for a submerged palaeolandscape viable for human occupation and movement along the Pacific Coast of South America during the Late Pleistocene.