Wetland paradise lost: Miocene community dynamics in large herbivorous mammals from the German Molasse Basin

Questions: What was the distribution of fossil mammal taxa in the Miocene German Molasse Basin? Were there changes in community structure during the terrestrial development of the Molasse Basin? Were community dynamics similar in the Molasse Basin to those in the rest of Europe? Data: We gathered the available Miocene large mammal herbivore occurrences from the southern German Molasse Basin [museum data mainly from Munich (Germany), with additional data from museums in Stuttgart (Germany) and Vienna (Austria)]. We used public data from NOW (Neogene of the Old World database, http://www.helsinki.fi/science/now) for comparison and as the source of ecological data for the species. Methods: We combined ecological data from the NOW database with distributions of herbivorous mammals within the Molasse Basin. We plotted the occurrences of taxa on a base map, and used the associated body size and dietary categories to plot these data on the map. We investigated the differences in the structure of communities in different time periods. We compared different time periods and differences among areas. We also compared the Molasse Basin and NOW data. Conclusions: The evolution of large-mammal communities in the Molasse Basin occurred in two phases: build up and decline. The build-up phase was characterized especially by a high abundance of small-sized browsers and mixed feeders. The diversity was especially high during the built-up phase, indicating a highly differentiated wetland habitat. The decline phase saw a very different community structure with fewer mixed feeders and with larger sized mammals dominating. The difference between these phases was largely the consequence of regional extinctions of species and genera. The Molasse Basin community dynamics also differ from those of the rest of Europe (NOW data).