1. Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, Colorado 80205, U.S.A
2. Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, Connecticut 06511, U.S.A,
3. Département des Géosciences, Université de Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland,