1. Department of Geology, Université de Liège, 14 allée du 6 Août, Liège 4000, Belgium
2. Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
3. University of Alaska Museum and Department of Geosciences, University of Alaska Fairbanks, 1962 Yukon Drive, Fairbanks, AK 99775, USA
4. Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK
5. CR2P CNRS-MNHN-UPMC Paris 6, Département Origines et Evolution, Muséum National d'Histoire Naturelle, CP 38, 57 rue Cuvier, 75005 Paris, France