We thank Lucy Flynn Zuccotti for collecting molds of the gorilla teeth and Dr. William Stanley for permission to study collections at the Field Museum of Natural History in Chicago. This paper was much improved with the help of comments by three anonymous reviewers. Computer systems were provided by Intergraph Corporation and SUN Microsystems, and the Surveyor 500 laser scanner was purchased with funds granted by the University of Arkansas. This project was supported in part by U.S. National Science Foundation grant SBR 9804882.