ACKNOWLEDGEMENTS

We thank M.R. Saccu (Talisman fossil Gallery project), who provided financial and moral support for this project. M. Feuerstack, A. MacDonald, and K. Shepherd (Canadian Museum of Nature) provided access to the fossils. We are grateful to R. Holmes (CMN) for helpful dicussusions, as well as M. Graham (CMN), and two anonymous reviewers of this paper whose comments greatly improved the manuscript. We also thank the Black Hills Institute for the loan of the premaxilla, as well as D. Weishampel (Johns Hopkins University) and L. Witmer (Ohio University) for encouragement and discussion.