1. Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, Alberta, T6G 2E1, Canada;
2. Field Museum of Natural History, Chicago, IL, U.S.A.
3. Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, 2-020J Katz Building, Edmonton, Alberta, T6G 2E1, Canada
4. Department of Geology and Geophysics and Peabody Museum of Natural History, Yale University, New Haven, CT 06520, U.S.A.
5. Temerty Chair in Vertebrate Palaeontology & Vice President, Natural History, Royal Ontario Museum, 100 Queen's Park Toronto, Ontario, M5S 2C6, Canada
6. Macaulay Curator, Division of Paleontology, American Museum of Natural History, New York, NY 10024, U.S.A.