CAI, CHEN-YANG, State Key Laboratory of Palaeobiology and Stratigraphy; Nanjing Institute of Geology and Palaeontology; Chinese Academy of Sciences; Nanjing 210008; China University of Chinese Academy of Sciences; Beijing 100049; China; School of Earth Sciences; University of Bristol; Life Sciences Building; Tyndall Avenue; Bristol; BS8 1TQ; United Kingdom, China