1. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
2. State Key Laboratory of Palaeobiology and Stratigraphy, Chinese Academy of Sciences, Nanjing 210008, China
3. Palaeobotany Research Group, University of Münster, 48149 Münster, Germany
4. University of Science and Technology of China, Hefei 230000, China
5. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 10000, China