ACKNOWLEDGMENTS

Thanks to C. Stock and L. Leighton for constructive reviews that improved an earlier version of this paper. B. Klingensmith assisted with data collection, and Jacqueline Smith assisted with polygon creation. D. Gneidovic (Ohio State Orton Geological Museum), K. Hauer (Miami University Limper Museum), and B. Hunda (Cincinnati Museum of Natural History) are thanked for access to and assistance with their collections. This research was supported by NSF EAR- 0922067, a grant from the American Chemical Society's Petroleum Research Fund, Ohio University Baker Fund and PACE Awards, and the Ohio University Department of Geological Sciences.