1. Institute of Geology; Chinese Academy of Geological Sciences; Beijing 100037 China
2. Key Laboratory of Stratigraphy and Paleontology; The Ministry of Land and Resources P.R.C; Beijing 100037 China
3. Birbal Sahni Institute of Palaeobotany; Lucknow 226007 India
4. Laboratory of Palaeobotany; Komarov Botanical Institute; Russian Academy of Sciences; St. Petersburg 197376 Russia