1. School of Earth Sciences & Key Laboratory of Mineral Resources in Western China (Gansu Province), Lanzhou University, Lanzhou, China
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS), Nanjing, China
3. Geological Survey of Gansu Province, Gansu Geological Survey Institute, Lanzhou, China
4. Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA
5. College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China