Endemic evolution and faunal turnover of the European Paleocene mammals

Up until this work started, the knowledge of the European Paleocene mammals was almost restricted to the faunas of Cernay-Berru (France) and Walbeck (Germany), which were considered approximately equivalent in age. Recently, the complete fauna of the Early Paleocene of Hainin (Belgium) became available for study after a long technical preparation process. The Paleocene epoch was completed thanks to the discovery of a new fauna of the latest Paleocene of Rivecourt (France), and by the discovery of a few mammal specimens in the Middle Paleocene of Maret (Belgium). It was therefore for the first time possible to study the evolution of the mammal diversity along the whole Paleocene. The study of the mammal fauna of Hainin resulted in the characterization and comparison of 20 species and morphotypes. Of these, 13 are new, and 6 previously described species from Hainin were more completely studied notably thanks to identification of additional material. As a whole, the fauna is dominated by small insectivorous taxa, and has very poor diversity in condylarths and plesiadapiforms, two groups that are abundant in other Paleocene faunas. The mammals from Maret are similar to those from Walbeck, and therefore suggest for the first time a correlation of Walbeck with the Middle Paleocene, i.e. significantly older than Cernay-Berru. Finally, 12 species of mammals from Rivecourt were identified and compared. The mammal assemblage is characterized by the occurrence of typical Paleocene taxa with the first modern mammals: a rodent and a carnivoran. The biochronology of the European Paleocene is revised thanks to the addition of the faunas of Hainin and Rivecourt, and the change in the age estimate of the fauna of Walbeck. New ELMAs are characterized, and new corresponding subdivisions of the MP reference-levels are proposed. The fauna of Hainin, of Danian age, is suggested to represent the first ELMA, corresponding to the MP1-3. The fauna of Walbeck is representative of the second ELMA, and corresponds to MP4-5. The Cernaysian was previously recognized, and corresponded to the MP6. However, the new definition of the Rivecourtian ELMA, corresponding to the MP6b, results in reattributing Cernay to MP6a. Finally, the existence of an important dispersal event around the Danian-Selandian transition was evidenced by the arrival of taxa such as Arctocyon and Plesiadapis from North America to Europe. The timing of the migrations accompanying the PEB was also reviewed, and it is shown that rodents and carnivorans arrive before the PEB in Europe, just as in North America.