1. College of Earth Sciences and Resources Chang'an University Xi'an 710054 China
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China
3. Florida Museum of Natural History University of Florida Gainesville FL 32611 USA
4. College of Life Sciences Capital Normal University Beijing 100048 China
5. School of Life Sciences Guangzhou University Guangzhou 510006 China