1. Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
2. Institute of Paleobiology, Polish Academy of Sciences, 00-818 Warsaw, Poland
3. Centre for Integrative Anatomy, Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
4. Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
5. Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, People's Republic of China