Late Miocene turnover in the Spanish mammal record in relation to palaeoclimate and the Messinian Salinity Crisis

Abstract

The latest Miocene and earliest Pliocene is a period of marked changes in geography and climate in the circum-Mediterranean area. Its geographical situation gives Spain a key position, and its fossil mammal record reflects these important geographical and climatic changes particularly well. The Spanish mammal record shows a gradual change of composition towards the typical Pleistocene and recent fauna, marked by several extinction and dispersal events. These events have the effect that northern Eurasian elements increase, while taxa that locally go extinct may live on in tropical areas. Superposed on this large scale trend, there are some events of short lived incursions of animals of African or south Asian origins, which seem to reflect a short reversal of this tendency and temporary geographical changes related to the Messinian Crisis. These latter incursions are detected very well in Spain but also in other parts of southern Europe. The Messinian Salinity Crisis is caused by interplay of tectonics, and global sea level variations which in turn depend on climate. While some of these changes were permanent, causing the replacement of central Italian insular faunas by mainland faunas, others were temporary probably allowing the short lived incursions of African mammals into SW Europe and certainly allowing for mammals to reach the Balearics, Corsica and Sardinia. We document an important event around 6.1 Ma, of mammals adapted to dry or open environments dispersing from Africa and SE Europe to SW Europe. During the Messinian desiccation phase, animals adapted to more humid environments reached some of the west Mediterranean islands, suggesting that, at least during part of the desiccation phase, a part of the former sea bottom was not desertic. Between 6.3 and 5.3 Ma tectonics united the island of Toscany to the European mainland, thereby closing a seaway of some 10 km wide and 100 m deep.