1. Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
4. Center for Research and Education on Biological Evolution and Environment, Nanjing University, Nanjing 210023, China