Ginkgo From The Upper Cretaceous In Jiayin Of Heilongjiang

"The living fossil"Ginkgo (G. biloba) has a long history in its evolution during the geological time. The origin and evolution of Ginkgo have been concerned and interested by paleobotanists and botanists. For the last decades, it has been more detailed in study of the evolution and the taxonomy of Ginkgo of China in Mid-Jurassic, Late Jurassic to Early Cretaceous and Paleogene, the three stages of geological ages. However, it is obviously a gap of in the Late Cretaceous, especially the mid-upper Late Cretaceous, which to be important for study better understanding of the evolution of Ginkgo and Gikgoales.The Upper Cretaceous are widely distributed in Jiayin area of Heilongijang, China, and fossiliferous in animals and plants, especially in Ginkgo fossils. Based on the anatomic study of the leaf cuticles of Ginkgo collected from the mid-upper Upper Cretaceous in Jiayin, the author has described 3 species of Ginkgo including Ginkgo adiantoides (Unger) Heer, G. pilifera Samylina and Ginkgo sp. The taxon Ginkgo sp. might be a new species of Ginkgo mainly due to its possessing the amphistomatal cuticle and other distinguished features. The taxonomic study of Ginkgo in this area would benefit significant for futher study of the evolution of Ginkgo during the Late Cretaceous.Moreover, the author analyzes and discusses the Late Cretaceous paleoclimate and paleogeography in Jiayin area , by means of anatomic and gross morphological study of Ginkgo leaf fossils and of the component of its associated flora. The author considers that it might be a thermophilous climate as the subtropic or the warm temperate-subtropic in general, and probably with shortly seasonally arid in climate during this time. The study would provide some new data for study of Late Cretaceous paleogeography and paleoclimate in Jiayin area.