I would like to thank Arthur Andersen of Virtual Surfaces for the use of the Emmersion Microscribe digitizer and for his assistance in editing digital data. This project was supported in part by grants from the Jurassic Foundation, Sigma Xi, and the LSU Museum of Natural Science. I am most grateful to my advisor, Judith Schiebout, for keeping me focused on the task at hand. I would like to thank the rest of my committee: Laurie Anderson, Barbara Dutrow, Daniel Hillmann, and John Wrenn for greatly improving the quality of this paper. Finally, I would like to thank Whitey Hagadorn and two anonymous reviewers for their comments and suggestions which also improved the quality of this paper.