1. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China; , , , ,
2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
3. Department of Earth Sciences, St. Francis Xavier University, Antigonish, NS, Canada B2G 2W5,
4. epartment of Geology, University of Dayton, 300 College Park, Dayton, OH 45469, USA;