Naihua Xue, Nanjing Institute of Geology and Palaeontology, Nanjing, China, Chengguo Guan, State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, China, Wei Wang, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China and Mingsong Li, Pennsylvania State University, Geosciences, State College, PA, United States