Environmental conditions vs. landscape. Assessment of the factors that influence small mammal fauna distribution in Southern Iberia during the latest Messinian by mean of stable isotopes

Abstract

Tropical conditions during the late Miocene in southwestern Europe influenced the continental environments. Although there are previous qualitative environmental interpretations of these continental landscapes during the late Miocene, quantitative environmental and paleohydrological data are scarce. A very long sequence of small mammals allowed to date the different continental drainage stages of the Granada Basin from latest Tortonian to the Holocene and to reconstruct qualitatively its environmental evolution. The study of the isotopic record of these fossil small mammals and sediments in the stratigraphic sequence of a latest Messinian paleo-lake in the Granada Basin has provided quantitative environmental and paleohydrological data, in order to know if the fluctuations in the faunal distribution were mainly influenced by the paleogeographic configuration, such as changes in the landscape of the basin, or by the climatic conditions. Open habitats with C3 plants predominated. Estimated quantitative data suggest an oxygen isotopic composition of meteoric waters ranging from −4.9 to −3.9‰, past temperatures from ~2.5°C to 4.7°C higher than the current ones, and summer relative paleohumidity from ~60% to ~70%. In this context, changes in the landscape, such as the reduction of the lacustrine system caused by tectonic activity, would affect taxa with high dependence on humid conditions.