1. Jack Satterly Geochronology Laboratory, Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada M5S 3B1
2. Instituto de Geociencias (CSIC-UCM), Dr. Severo Ochoa 7, 28040 Madrid, Spain
3. Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia, Canada B4P 2R6
4. Área de Paleontología, Facultad de Ciencias, Universidad de Extremadura, 06006 14 Badajoz, Spain
5. Geological Surveys Branch, Department of Natural Resources and Energy Development, Box 5040, Sussex, New Brunswick, Canada E4E 5L2