Palaeogene floristic patterns in the southwest of Europe (France and Spain)

The Eocene-Oligocene transition represents the most drastic climatic turnover of the Cenozoic characterised by a drop of temperatures, increase of seasonality and aridity. This global climatic change, that started in the latest Eocene, affected the vegetation across Europe in different ways and suggests a regional climatic and floristic heterogeneity. For instance, significant differences in paleodiversity are observed between two coeval uppermost Eocene plant localities from south of Europe i.e., Alès (Gard, South France) and Sarral (Catalonia, NE Iberian Peninsula) where Alès Basin shows a higher diversity of conifers but lower number of leguminous plants than in Sarral. Surprisingly, almost the same genera recognized in the latest Eocene from Alès, are observed in the neighbouring lower Oligocene locality from Luberon. Similar results are observed between Sarral and the neighbouring lower Oligocene locality from Cervera. It appears that the floral diversity from south Europe was less disturbed compared to what occurs with mammals at the Eocene-Oligocene boundary. Nevertheless, the combination of taphonomic and paleoecologic studies carried out in these plant localities reflect remarkable changes in plant biomes composition mainly in riparian vegetation and the plant community located distally from the lake. The factors that drew these differences may be related to the particular environmental conditions of each basin.