Spatial and temporal variation in European Neogene large mammals diversity

Large mammals diversity (i.e., ungulates or hoofed mammals) is investigated over the whole European geographic area and through a period extending from the Late Oligocene, around 27 Ma ago, to the Early Pliocene, around 3 Ma ago. Qualitative and quantitative spatial and temporal patterns are discussed thanks to the analysis of a large dataset of localities (695) that yielded large mammals and distributed over this period and area. We show that the Miocene is a key period in the installation of modern faunas in Europe; modern ruminants (mainly cervids and bovids) largely develop during the period considered and replace the Oligocene-inherited dominant faunas. These replacements are triggered by different factors, often extrinsic and constitute the roots of the present situation. Indeed, a complex interplay between geographic (palaeogeographic reorganisations) and climatic factors (warming and cooling events) can be invoked to understand how faunas change. Geography seems to play a crucial role in the Early Miocene when it allows migration routes to open between Europe, Asia and Africa and in turn leads to a drastic increase of ungulate diversity that seems to be maintained in the Middle Miocene under the warm equable climates of the Miocene Climatic Optimum. The Late Miocene sees a global climatic deterioration leading to a decline in large mammals diversity and represents the root of the extant depleted situation. Regional comparisons indicate that endemism was already strong in the Miocene, especially in south-eastern Europe, and that strong climatic belts already seem to have an impact on mammal communities since the Late Miocene. The roots of the extant situation (endemism and low diversity) are therefore more complex and probably older than previously thought; they are to be looked for before the Quaternary Climatic Cycles and are the by-product of deep-time geographic and climatic events.