1. Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA
   • Jin Meng
2. Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box 643, Beijing 100044, China
   • Jin Meng,
   • Yuanqing Wang &
   • Chuankui Li

F.L., S.L., Y.J., J.J., H.F., G.L. and N.Y. designed all experiments. F.L., S.L., Y.J., J.J., H.F., G.L., D.D., S.D. and X.Z. performed the experiments. All authors analysed the data. F.L., J.W. and N.Y. contributed to manuscript preparation. N.Y. wrote the manuscript.

The authors declare no competing financial interests.