1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany; Chinese Academy of Sciences; Beijing 100093 China
2. Paleontological Institute of Shenyang Normal University; Shenyang 110034 China
3. Research Center of Paleontology; Jilin University; Changchun 130026 China
4. Department of Geology/Biology; Indiana University; Bloomington IN 47405 USA
5. Florida Museum of Natural History; University of Florida; Gainesville FL 32611-7800 USA