Acknowledgments

This research effort was part of a continuing University of California Museum of Paleontology (UCMP) field program headed by Dr. Wiliam A. Clemens. I thank those associated with the UCMP who helped to see this project to completion, most notably Dr. Clemens who suggested and supervised the project, and the members of UCMP field parties during the years 1984 to 1989 especially: Mark Goodwin, Dr. J.H. Hutchison, Kyoko Kishi, Dr. Laurie Bryant, Allen Tedrow, Matthew Colbert, James Foster, Dr. Anthony Runkel, and Dr. Zhexi Luo. Special thanks to Mark Goodwin and Kyoko Kishi for fossil preparation and to those who sorted screenwash concentrate from McGuire Creek.

I am grateful to the many local ranchers who allowed access to their land, and for their friendship and hospitality, including Lester and Cora Engdahl, Robert and Jane Engdahl, Judd and Jay Twitchell, Clay Taylor, and their families. Don and Marge Beckman of Fort Peck contributed the use of a motorboat which made fieldwork and fossil collection in areas far from roads logistically feasible.

For their helpful comments and discussions I thank, Dr. Bryant, Dr. Runkel, Dr. J. David Archibald, Dr. Carol Hotton, Dr. Douglas Nichols, Dr. J. Keith Rigby Jr., Dr. Carl Swisher, Dr. Lowell Dingus, Dr. Jennifer Hogler, Dr. Zhexi Luo, Dr. Judd Case, Dr. Richard Fox, Gayle Nelms, and Robert Dundas. Special thanks to Dr. Hutchison for hours of stimulating discussion on various aspects of the Cretaceous-Tertiary transition in eastern Montana.

Dr. Archibald, Dr. J.A. Lillegraven, and Dr. P. Sadler carefully reviewed the original manuscript and provided many helpful suggestions. Dr. Hotton kindly allowed me to report the age of a number of rock samples from McGuire Creek based on her analyses and interpretations of palynofloras.

Specimens were loaned by Dr. L. Van Valen of the University of Chicago and Mary Ann Turner of the Yale Peabody Museum. Financial support was provided by the Department and Museum of Paleontology, University of California at Berkeley (Annie M. Alexander Endowment); the University of California at Berkeley (Regents Fellowship and the Alfred F. Moore and Chella D. Moore Scholarship); National Science Foundation Grant no. BSR-85-13253 to Dr. Clemens and the Board of Trustees of the Raymond M. Alf Museum.

I especially want to thank my parents Lionel and Delores Lofgren, and my wife Laura, for their support during my academic studies, which made completion of this project possible.