1. Department of Micropalaeontology; Nanjing Institute of Geology and Palaeontology; Chinese Academy of Sciences (CAS); Nanjing 210008 China
2. State Key Laboratory of Palaeobiology and Stratigraphy (SKLPS); Nanjing Institute of Geology and Palaeontology; Chinese Academy of Sciences (CAS); Nanjing 210008 China
3. Department of Earth Sciences; Natural History Museum; London SW7 5BD UK