1. Slovak Academy of Sciences Earth Science Institute Bratislava 84005 Slovakia
2. Dipartamento di Fisica e Scienze della Terra Università degli Studi di Ferrara Via Saragat 1 44122 Ferrara Italy
3. Department of Palaeontology University of Vienna Josef‐Holaubek‐Platz 2 1090 Vienna Austria
4. Department of Geosciences University of Tübingen Schnarrenbergstrasse 94‐96 72076 Tübingen Germany