中文摘要：

甘肃宝积山盆地中侏罗统窑街组发现茨康类植物化石,通过对其外部形态和表皮构造研究,认定为石拐茨康叶（Czekanowskia（Vachrameevia）shiguaiensis）。对比当前化石及其现存最近对应种（the nearest living equivalent species）—Ginkgo biloba L.的气孔比率,得到宝积山盆地在中侏罗世的古大气CO2体积分数为1.55×10-（-3）,数值接近GEOCARBⅢ碳平衡模型的拟合曲线,表明茨康叶属植物也是恢复古大气CO2体积分数的良好材料。同时,通过角质层特征进行古环境重建,结果表明宝积山盆地在中侏罗世时期气候较为温和湿润。

英文摘要：

Czekanowskialean fossils are discovered from the Middle Jurassic Yaojie Formation in the Baojishan Basin,Gansu.They are assigned to Czekanowskia（Vachrameevia） shiguaiensis Sun et al.according to the leaf morphology and epidermal structures.Compared the stomatal ratio between the fossil and the nearest living equivalent species--Ginkgo biloba L.,the value of CO2 concentration in the Middle Jurassic Baojishan Basin was deduced as about 1.55 × 10-（-3）,which is closer to fitted curve of the GEOCARB Ⅲ carbon balance model.It shows that Czekanowskia（Vachrameevia） shiguaiensis might be a good fossil plant for reconstructing paleoatmospheric CO2 level.The results indicate that the climate of Baojishan Basin was warm and wet in the Middle Jurassic.