Ecological evolution in northern Iberia (SW Europe) during the Late Pleistocene through isotopic analysis on ungulate teeth

Abstract. During the Late Pleistocene, stadial and interstadial fluctuations affected vegetation, fauna, and human groups that were forced to cope with these pronounced climatic and environmental changes in time and space. These changes were especially abrupt during the Marine Isotopic Stage (MIS) 3. However, little is still known about the local and regional climatic conditions experienced by hominins in Europe. Here we reconstruct the climatic trends in northern Iberia considering the stable isotopic composition of ungulate skeletal tissues found in archaeological deposits dated between 80 to 15,000 cal BP. The carbon and oxygen isotopic composition preserved in the carbonate fraction of tooth enamel provides a reliable and high-resolution proxy of the food and water consumed by these animals, which is indirectly related to the local vegetation, environment, and climate, allowing us to estimate paleotemperatures and rainfall data. This study presents 44 bovine, equid, and cervid teeth from five archaeological sites in the Vasco-Cantabrian region (El Castillo, El Otero, Axlor, Labeko Koba, Aitzbitarte III) and one in the Mediterranean area (Canyars), where human evidence is attested from the Mousterian to the Magdalenian. The carbon isotope values reflect animals feeding on C3 plants with a mix-feeder diet mainly developed in open environments. However, carbon isotope value ranges point to differentiated ecological niches for equids and bovines, especially during the Aurignacian in the Vasco-Cantabrian region. Temperature estimations based on oxygen isotopic compositions and rainfall obtained from carbon isotopic compositions indicate colder and more arid conditions than nowadays from the Late Mousterian to the Aurignacian. The contemporary Mediterranean site shows slightly lower temperatures related to an arid period when animals mainly graze in open landscapes. In the Vasco-Cantabrian region, during the MIS2, the Gravettian data reflect a landscape opening, whereas the Magdalenian point to warmer conditions but still arid.