Department of Mechanical Engineering, Tsinghua University, Beijing, P. R. China.|Department of Mechanical Engineering, Tsinghua University, Beijing, P. R. China.|Department of Mechanical Engineering, Tsinghua University, Beijing, P. R. China.|Department of Mechanical Engineering, Tsinghua University, Beijing, P. R. China.|Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, P. R. China.|Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, P. R. China.