New Material Of Ginkgo Leaves From Lower Cretaceous Of Huolinhe Coal Field, Inner Mongolia, China

Early Cretaceous is an important period for the evolution and early diversity of Ginkgo. The study of the Early Cretaceous Ginkgo, as well as its associated Ginkgoaleans, plays an important role for study of the earlier evolution and evolutionary history of Ginkgo.The Early Cretaceous Ginkgo leaves from Huolinhe in Inner Mongolia, China are rich in composition and well-preserved in cuticles. In this thesis the author made anatomic study of the fossil leaves of Ginkgo, mainly in cuticle study and described some new material of Ginkgo, which provided new and supplementary data for better understanding the known species of Ginkgo reported before. Moreover, the author found also a new taxon, Ginkgo sp., in which the leaves are deeply dissected into thin and narrow lobes with well-developed trichomes in both epidermal surfaces, and show probably a new species of Ginkgo. The above-mentioned results of the present study appear to benefit the improvement for the taxonomic research level of fossil Ginkgo, and are significant for further study of the evolution of Ginkgo in northeastern China during the Early Cretaceous time.In addition, the author analyzes the paleoclimate and paleophyto- geography in the Huolinhe area in Early Cretaceous, and suggest that the paleoclimate of this area might be seasonally warm and humid during the Early Cretaceous time.