1. Department of Stratigraphy and Paleontology; Faculty of Science and Technology; University of the Basque Country (UPV/EHU); Ap. 644 E48080 Bilbao Spain
2. Department of Earth Sciences; University of Firenze; via La Pina 4 I-50121 Firenze Italy
3. Department of Mineralogy and Petrology; Faculty of Science and Technology; University of the Basque Country (UPV/EHU); Ap. 644 E48080 Bilbao Spain