[1] Gansu Agr Univ, Coll Life Sci & Technol, Inst Vertebrate Paleontol, Lanzhou 730070, Gansu, Peoples R China
[2] Russian Acad Sci, Paleontol Inst, Moscow, Russia
[3] Nat Hist Museum, Dept Palaeontol, London, England
[4] Capital Normal Univ, Coll Life Sci, 105 Xisanhuanbeilu, Beijing 100098, Peoples R China
[5] Smithsonian Inst, Dept Paleobiol, Natl Museum Nat Hist, Washington, DC 20013 USA