1. 1Yunnan Key Laboratory for Palaeobiology & MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming 650091, China
2. 2Museum of Natural History, University of Oxford, Oxford, OX1 3PW, UK
3. 3All Souls College, University of Oxford, Oxford, OX1 4AL, UK