1. College of Life Sciences and Academy for Multidisciplinary Studies Capital Normal University 105 Xisanhuanbeilu Haidian District, Beijing 100048 China
2. Department of Paleobiology National Museum of Natural History Smithsonian Institution Washington DC 20013‐7012 USA
3. A. A. Borissiak Palaeontological Institute Russian Academy of Sciences 117647 Moscow Russia
4. Natural History Museum Cromwell Road London SW7 5BD UK