1. School of Geosciences, University of Edinburgh, Grant Institute, James Hutton Road, Edinburgh EH9 3FE, UK;
2. University Museum of Zoology Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
3. Department of Geology, University of Leicester, Leicester LE1 7RH, UK;
4. School of Ocean & Earth Science, University of Southampton, National Oceanography Centre, European Way, University Road, Southampton SO14 3ZH, UK;
5. Sedgwick Museum, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK