Jeremy B. C. Jackson is director of the Center for Tropical Paleoecology and Archeology at the Smithsonian Tropical Research Institute and the William and Mary B. Ritter Professor of Oceanography at the Scripps Institution of Oceanography. Scott Lidgard is an associate curator of fossil invertebrates in the Department of Geology at the Field Museum, lecturer in the Committee on Evolutionary Biology at the University of Chicago, and adjunct associate professor of biology at the University of Illinois, Chicago. Frank K. McKinney is a professor emeritus in the Department of Geology at Appalachian State University and Honorary Research Fellow in the Department of Palaeontology at The Natural History Museum, London. Jeremy B. C. Jackson is director of the Center for Tropical Paleoecology and Archeology at the Smithsonian Tropical Research Institute and the William and Mary B. Ritter Professor of Oceanography at the Scripps Institution of Oceanography. Scott Lidgard is an associate curator of fossil invertebrates in the Department of Geology at the Field Museum, lecturer in the Committee on Evolutionary Biology at the University of Chicago, and adjunct associate professor of biology at the University of Illinois, Chicago. Frank K. McKinney is a professor emeritus in the Department of Geology at Appalachian State University and Honorary Research Fellow in the Department of Palaeontology at The Natural History Museum, London.