1. Charles University, Faculty of Science, Institute of Geology and Palaeontology, Albertov 6, Prague 2, 128 43, Czech Republic;
2. Géosciences Environnement Toulouse (GET), Univeristé de Toulouse, CNRS, UPS, IRD, 14 avenue Edouard Belin, F-31400 Toulouse, France;
3. Koněprusy 45, 266 01 Beroun, Czech Republic;
4. Tisová 29, 261 42 Bohutín, Czech Republic