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Mid-Miocene latitudinal environmental gradient in western Europe
18/12/2004 00:00 | Durée 00:09:55

Intervenants : Loïc Costeur , 1UMR CNRS 5125, Université Claude Bernard Lyon 1, Bâtiment GEODE, Villeurbanne, France .  

Mid-Miocene latitudinal environmental gradient in western Europe : mammals and vegetation compared The middle Miocene (16 to 11 My) is a key period in the Cenozoic climatic evolution. It represents the last warmest episode of the Tertiary (Miocene Climatic Optimum) in a general cooling trend and development of major permanent Antarctic ice sheets (Zachos et al., 2001). In this context, terrestrial ecosystems evolved towards their present-day structure. We investigated how the western European middle Miocene vegetation and mammalian communities responded to this climatic evolution. We found that southwestern Europe (south and central Spain) was dominated by very arid environments and that progressively more closed and humid conditions were encountered going northward. The pollen grain contents of mega-mesothermic plants with higher water requirements increase and the mammalian communities body weight distributions progressively change from sub-desertic to closed and humid environments from central Spain to northeastern Germany. Thus a strong latitudinal environmental gradient already existed by mid-Miocene times and probably finds explanations in the global climatic and tectonic events that took place during this time-period.