1. Honors Program and Schmid College of Science and Technology, Chapman University, One University Drive, Orange, California 92866 U.S.A.,
2. Museum of Paleontology, University of California, 1101 Valley Life Sciences Building, Berkeley, California 94720 U.S.A.,
3. Royal Ontario Museum, 100 Queens Park, Toronto, Ontario M5S 2C6, Canada,
4. Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada