1. Department of Geology and Geophysics; Yale University; 210 Whitney Avenue New Haven CT 06511 USA
2. Department of Vertebrate Zoology; National Museum of Natural History; Smithsonian Institution Washington DC 20560 USA
3. Mount Desert Island Biological Laboratory; Salisbury Cove ME 04672 USA
4. School of Earth Sciences; University of Bristol; Queen's Road Bristol BS8 1RJ United Kingdom
5. School of Biological Sciences; University of Bristol; Woodland Road Bristol BS8 1UG United Kingdom
6. Department of Biological Sciences; Dartmouth College; Hanover NH 03755 USA