| The Lower Cretaceous Changcai Formation is distributed mainly in Laotougou and Tuntianying of Yanji County; Songxiaping, Changcai and Dajinchang of Helong County in the eastern Jilin, NE China. It is an important coal-bearing strata consisting mainly of array sandstone, sandy conglomerate and gray-green conglomerate intercalated with black shale, carbonaceous mudstone and coal beds, yielding abundant fossil plants represented by Osmunda cratacea Samylina, Coniopteris burejensis (Zalessky) Seward, Acanthopteris gothani Sze, Nilssoniopteris prynadae Samylina, N. platyrachis (Samylina) Sun et al, Nilssonia sinensis Yabe et Oishi, Phoenicopsis speciosa Heer, Elatocladus manchurica (Yokoyama) Yabe, etc. (BGMRJ, 1982; Wei W Y, Sun Y W, et al, 2005) were found from the Changcai Formation in Helong of Jilin, China, which indicates a warm and humid temperate flora of the Sibirian-Canadian Floristic Region. Since 1960's, a number of genera and species of Ginkgoale and Czekanowskiales have been recorded from the Changcai Formation in this area (Yang, 1959; Zhou, et al, 1980; BGMRJ, 1982; Shang, 1992), based on the morphological studies of the leaf impressions. The author had been ongoing geological investigation of the Lower Cretaceous Changcai Formation in Changcai Coal-Mine of the Helong County during 2003~2004 and collected lots of Ginkgoales and Czekanowskiales leaf fossils from the Changcai Formation of Changcai Coal-Mine. Under cuticular study of leaf compression fossils, 7 species belonging to 3 genera of Ginkgoales, including, Ginkgo coriacea Florin, G. truncata (Li) Chen, G. sibirica (Heer) Seward, G. adiantoides (Unger) Heer, G. sp., Bairea minima Yabe et Oishi, Sphenobairea cf. longifolia (Pomel) Florin and 3 species belonging to 2 genera of Czekanowskiales, including Phoenicopsis (P.) doludenkoae Samylina, P. (P.) sp., Czekanowskia Setacea Heer are recognized from the Early Cretaceous Changcai Formation of Changcai Coalmine, Helong of Jilin, China. Among them, Ginkgo coriacea Florin, G. truncata (Li) Chen, G. adiantoides (Unger) Heer and Phoenicopsis (P.) doludenkoae Samylina are recorded in this area for the first time. Ginkgo adiantoides was often found from the Cenozoic in Eurasia. Its appearance in the Lower Cretaceous shows that it has a rather long geological history and a wide range of environmental proxies. Ginkgo sibirica (Heer) Seward was usually seen in the Lower and Middle Jurassic, It is rare in the Lower Cretaceous, the present record shows it can also survive in the Early Cretaceous. Phoenicopsis (P.) doludenkoae Samylina was often described as Phoenicopsis speciosa Heer, especially when the specimens are impressions in preservation, and loss its important stratigraphic significance. All these are important to study the geological and geographical distribution and evolution of Ginkgoales and Czekanowskiales. The living Ginkgoales is only represented by a single living species, Ginkgo biloba, native to China, but Ginkgoales was a flourishing group in the geological history, which distributed all over the world in the Mesozoic. The cuticular analysis of leaf compression fossils has been an important subject in paleobotany all through. The fossil cuticle containing stomata may be regarded as a skeletal record of environmental change. Woodward (1987) validated the plant species-specific inverse relationship between atmospheric CO2 concentration and stomatal density (SD) or stomatal index (SI) first. Ginkgo leaves are sensitive to atmospheric CO2 concentration, so Paleo-CO2 levels can be valuated through investigating the stomatal parameters of Ginkgo leaf fossils. The atmospheric CO2 levels during the development of Early Cretaceous Changcai Formation was valuated as 420~590 μmol.mol-1, averaging 498.6 μmol.mol-1, which lower than...
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