1. L. Hou, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Post Office Box 643, Beijing 100044, China.
2. L. D. Martin, Natural History Museum, University of Kansas, Lawrence, KS 66045, USA.
3. Z. Zhou, IVPP, Chinese Academy of Sciences, Post Office Box 643, Beijing 100044, China, and Natural History Museum, University of Kansas, Lawrence, KS 66045, USA.
4. A. Feduccia, Department of Biology, University of North Carolina, Chapel Hill, NC 27514, USA.