(1. College of Biological Science and Engineering, North University of Nationalities, Yinchuan 750021, China; 2. College of Life Sciences, Ningxia University, Yinchuan 750021, China; 3. Ningxia Geology Museum, Yinchuan 750021, China; 4. College of Life Sciences, Capital Normal University, Beijing 100048, China; 5. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China)