As a boy growing up in Lake Arrowhead, Calif., in the 1950s, Tim White used to collect obsidian flakes and pottery shards at ancient Indian campsites in the nearby San Bernardino Mountains. (He also amassed a menagerie of lizards and snakes, much to his mother's dismay.) Told by a high school guidance counselor that his dream of studying dinosaurs was unacceptable, White headed to the University of California, Riverside, to major in biology--and eventually anthropology as well. He spent his weekends catching rattlesnakes.
But he never lost his childhood fascination with prehistory, and today he is one of the world's...