1. Department of Geosciences, Wachenheim Science Center, 18 Hoxsey Street, Williams College, Williamstown, MA 01267, USA
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing, 210008, PR China
3. Department of Biology, Hopper Science Center, 59 Lab Campus Drive, Williams College, Williamstown, MA 01267, USA