1. Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH−8903 Birmensdorf, Switzerland;
2. Palaeobiology programme, Department of Earth Sciences, Department of Evolutionary Biology, Uppsala University, Norbyvägen 18/D, SE−752 36 Uppsala, Sweden;
3. Institut National de la Recherche Agronomique, UMR Biodiversité, Gènes et Ecosystèmes, 69, Route d’Arcachon, F−33612 Cestas Cedex, France