For the help given in the preparation of this book, the editors are indebted to Stanley Awramik, Museum of Comparative Zoology, Harvard University; Donald Baird, Curator, Department of Geological and Geophysical Sciences, Princeton University; UmeshBanerjee, Department of Geological Sciences, Harvard University; Elso S. Barghoorn, Professor of Botany, Harvard University; Joan Bliss, Office of the Councillor Scientific, Australian Embassy, Washington, D. C; Richard Bremner, Programming Manager for llliac, Burroughs Corporation, Paoli, Pa.; Carol Campbell, Museum of Comparative Zoology, Harvard University; Frank Carpenter, Fisher Professor of Natural History, Harvard University; Robert L. Caroll, Redpath Museum, McGill University, Montreal; Joseph Cope, Gilbert Cope Foundation, West Chester, Pa.; Ross Dalen, Control Data Corporation, Minneapolis; Irven DeVore, Professor of Anthropology, Department of Social Relations, Harvard University; Peter Dodson, Department of Geology and Geophysics, Peabody Museum of Natural History, Yale University; Daniel Fisher, Museum of Comparative Zoology, Harvard University; Roger Sheridan Fouts, Department of Psychology, University of Oklahoma, Norman; Richard D. Fox, Associate Professor of Geology and Zoology, University of Alberta,Edmonton; Peter Galton, Department of Zoology, University of Bridgeport, Conn.; Shirley Hartman, Chief of Exhibit Design, Peabody Museum of Natural History, Yale University; Nicholas Hotton III, Curator, Fossil Amphibians and Reptiles, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D. C.; James A. Jensen, Curator, Earth Sciences Museum, Brigham Young University, Dinosaur National Museum, Provo, Utah; Glenn L. Jepsen, Professor of Vertebrate Paleontology, Princeton University; Richard Kay, Peabody Museum of Natural History, Yale University; Zofia Kielan - Jaworowska, Polska Akademia Nauk, Warsaw, Poland; Herbert Killackey, Visiting Assistant Professor, Division of Biological Sciences, Brown University, Providence, R. I.; Victoria Kohler, Museum of Comparative Zoology, Harvard University; Frank Long, Film Officer, Australian News and Information Bureau, New York City; Copeland McClintock, Assistant to the Director, Peabody Museum of Natural History, Yale University; Jesse Merrida, Museum Specialist, Department of Paleobiology, National Museum of,Natural History, Smithsonian Institution. Washington, D. C.; Judith H. Metzger, Research Assistant, Department of Geological Sciences, Harvard University; Lorus Milne, Professor of Zoology, University of New Hampshire, Durham; David R. Pilbeam, Associate Professor of Anthropology, Yale University; Edward S. Ross, California Academy of Sciences, Golden Gate Park, San Francisco; Dale Russel, Chief, Paleontology Division, National Museum of Natural Sciences of Canada, Ottawa; Bobb Schaeffer, Chairman and Curator, Department of Vertebrate Paleontology, American Museum of Natural History, New York City; Charles Schaff, Museum of Comparative Zoology, Harvard University; Charles Smart, Department of Geological and Geophysical Sciences, Princeton University; William N. Tavolga, Research Associate, Department of Animal Behavior, American Museum of Natural History, New York City; С Richard Taylor, Director, Concord Field Station, Bedford, Mass.; Richard H. Tedford, Curator, Department of Vertebrate Paleontology, American Museum of Natural History, New York City; Keith S. Thomson, Associate Professor of Biology, Peabody Museum, Yale University; Howard Topoff, Research Associate, American Museum of Natural History, New York City; Karl M. Waage, Professcr, Department of Geology and Geophysics, Peabody Museum of Natural History, Yale University.