1. 1Department of Palaeontology, Natural History Museum Luxembourg, 25 rue Münster, Luxembourg City 2160, Luxembourg
2. 2Earth Sciences, Box 5062, Tennessee Tech University, 1 William L Jones Drive, Cookeville, Tennessee 38505, USA
3. 3Department of Earth and Planetary Sciences, The University of Tennessee, 1621 Cumberland Avenue, Knoxville, Tennessee 37996, USA