1. School of Earth and Space Sciences, Peking University, 5 Yiheyuan Road, Beijing 100871, China.
2. Department of Comparative Biology and Experimental Medicine, University of Calgary, 3330 Hospital Drive, Calgary, Alberta T2N 1N4, Canada.
3. State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS), 39 East Beijing Road, Nanjing, Jiangsu Province 210008, China.
4. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, Sichuan Province 610041, China.
5. Research Center of Palaeontology and Stratigraphy, College of Earth Sciences, Jilin University, Changchun, Jilin Province 130061, China.
6. Department of Organismal Biology and Anatomy, Biological Sciences, The University of Chicago, Chicago, IL 60637, USA.