Paleobiogeography of Early/Middle Miocene terrestrial gastropods in Central Europe: An approach using similarity indices

• Land snail faunas (European Miocene) were compared by cluster analyses (3 indexes).
• Most of the recovered clusters can be explained by geography and/or age.
• Clusters from the OSM of Bavaria and Baden-Württemberg were consistently recovered.
• Some clusters are more variable and cannot be fully explained at the moment.
• A solid taxonomic framework forms the required basis for palaeobiogeographic works.

Terrestrial gastropods are a common faunal element in continental Miocene fossil Lagerstätten of Europe. Although having lived during a time span that includes the Miocene Climatic Optimum and the devastating Ries/Steinheim meteorite impacts, the state of knowledge about their faunal composition and geographic distribution is surprisingly incomplete. The land snail faunas of 30 different Early and Middle Miocene deposits of Central Europe (European Mammal Neogene zones MN 4 to MN 8) were compared using statistical methods (cluster and NMDS analyses, using the Ochiai, Simpson and Kulczynski indices). This includes 300 different taxa identified so far. Most of the analyzed deposits were part of the Miocene Paratethys and are today located in France, SW Germany (Baden-Württemberg state), SE Germany (Bavaria state), Austria, Poland, and Hungary. Cluster analyses resulted in different clusters, the majority of which can be explained by their geographic situation and/or by their distribution in time (e.g., the consistently recovered Baden-Württemberg and Bavaria clusters and the Bakony Mountains cluster). The remaining clusters cannot be fully explained so far, but some possibilities are explored here. Our results reveal the power of a solid taxonomic framework as a basis for palaeobiogeographic studies. As such, more “basic” palaeontological studies are required to strengthen future analyses.