ACKNOWLEDGMENTS

The authors wish to acknowledge K. Waggoner for her many helpful suggestions, R. Mapes for guidance on Paleozoic ammonoids and ammonoid taxonomy, G. Westermann for discussions of the tie-point model, N. Levine and J. Frizado for assistance with ArcGIS, two anonymous reviewers of an earlier version of the manuscript for many insightful critiques and helpful suggestions, and A. Avruch for ideas on the text.