1. Department of Geology and Paleontological Institute, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, KS 66045, USA;
2. Natural History Museum, Cromwell Road, London SW7 5BD, UK;
3. State Key Laboratory of Palaeobiology and Stratigraphy; Center for Excellence in Life and Paleoenvironment, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China;
4. School of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, UK