Beijing Museum of Natural History Beijing 100050 China;
Dinosaur Tracks Museum CB 172 University of Colorado at Denver Colorado 80217-3364 USA;
Archaeological Research Institute of Shaanxi Province Xi 'an Shaanxi 710054 China;
Department of Environmental Sciences Tokyo Gakugei University Koganei Tokyo 184-8501 Japan;
School of Earth and Space Sciences Peking University Beijing 100871 China;