Genera Ginkgo Linné And Ginkgoites Seward From Sandaoling Middle Jurassic Flora Of Turpan-Hami Basin In Xinjiang,North China

Studied materials were yielded from the coal-bearing strata from the Middle Jurassic in Xinjiang Province, Northwestern China. As one of the most important taxa in the Jurassic flora, Ginkgopsida are the dominant coal-forming plants in the Jurassic of Northern China. A thorough study on the exquisitely preserved Ginkgo Linné and Ginkgoites Seward fossil leaves have been done in terms of both the morphology and cuticle structure. So far as known, 4 species are assigned to Ginkgo while another 6 species are assigned as Ginkgoites including one new species: Ginkgo digitata(Brongniart) Heer, G. cf. dissecta Schweizter et Kirchner, G. parasingularis Kilpper, G. yimaensis Zhou et Zhang; Ginkgoites borealis Li, G. cf. marginatus(Nathorst) Florin, G. obrutschewii(Seward), G. xishanyaoensis sp. nov., G. sp. 1 and G. sp. 2.Meanwhile, an overview of geological and geographical distribution of these two morphogenera has sorted and analyzed. Both Ginkgo and Ginkgoites are quite prosperous in Early and Middle Jurassic, with more than 30 species in total spreading in most part of North Hemisphere such as East Sibera, Japan, China, Middle East as well as UK. However, the number of species declined dramatically in the Late Jurassic, which might indicate a change of the global climate. The results add new evidence to Sandaoling Middle Jurassic Flora. Besides, the study is of great significance for the distribution and the diversity of these two genera during the Jurassic period.