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Abstract A new method for reconstructing paleoenvironments using the pavement cell characteristics of Middle Jurassic ginkgoalean fossils from the Yaojie and Baojishan basins, Gansu Province, China, is presented. Specifically, we use present-day relationships between the length-to-width (L/W) ratio of leaf pavement cells of Ginkgo biloba and mean annual temperature (MAT), mean annual precipitation (MAP), and relative humidity (RH). Primary analyses indicate that the L/W ratio of Ginkgo biloba pavement cells is negatively correlated with MAT, MAP, and RH, and linear regression equations can be established. Based on these equations, paleoclimatic parameters were inferred using the ginkgoalean fossil data. The estimated paleotemperatures in the Yaojie and Baojishan basins during the Middle Jurassic are approximately 6 °C higher than those of the present day, which is consistent with the results of the currently used stomata ratio method and the global CO 2 prediction model. We deduce that paleoprecipitation in the basins was approximately 460 mm higher and paleohumidity approximately 20% higher than current conditions and thus the two basins exhibited humid subtropical conditions during the Middle Jurassic. Fossil flora and spore-pollen assemblage data from the study areas corroborate the new observations. [ABSTRACT FROM AUTHOR]

Abstract: The morphology and epidermal structure of the type material of Ginkgoites obrutschewii (Seward) Seward (1911, 1919), a species established for isolated leaves from the Jurassic of Northwestern China, have been revised based on the type material and recent findings from a geographically close, coeval locality. A diagnosis, missing in the original publication, is provided and a lectotype is designated. Numerous specimens of Ginkgoites/Ginkgo leaves without epidermal structure, that were ascribed to this species over the last century solely on the basis of the leaf morphology, have to be classified as Ginkgoites sp. This change restricts the known distribution of G. obrutschewii to the Middle Jurassic of the Xinjiang Uygur Autonomous Region in Northwestern China. [Copyright &y& Elsevier]

Tertiary leaf compressions of a Ginkgo plant with cuticle displaying all taxonomically important epidermal features are reported for the first time from Greece, and for the Mediterranean area as a whole. The fossils are from Upper Miocene sediments of Vegora, north-western Greece, and assigned to Ginkgo adiantoides (Unger) Heer. The most conspicuous cuticle characteristics are prominent papillae on the subsidiary cells that sometimes completely cover the stomatal apertures. Such papillae also occur in leaves of G. adiantoides from the Pliocene of eastern Central Europe, but are absent in leaves from the Pliocene of Germany also assigned to this species. We observed a high variability in the degree of papillosity of subsidiary cells of stomata in leaves of living Ginkgo biloba that exhibited prominent papillae in mature sun leaves and a total lack of papillae in shade leaves of a potted plant. This may suggest that differences in epidermal characters between the fossil leaves from Greece and Germany are due to ecotypical/intraspecific variability and not to genetically fixed specific differences. It also suggests that a number of Tertiary Ginkgo species from Eurasia that were distinguished from G. adiantoides by having papillate epidermis cells and subsidiary cells of the abaxial cuticle should be included within G. adiantoides. Two lineages of Ginkgo can be distinguished for the Tertiary of the Northern Hemisphere. From the Palaeogene high latitudes leaves were reported that exhibit upper epidermis cells with prominent papillae similar to those of older Mesozoic Ginkgo, whereas G. adiantoides lacks the papillae of the upper epidermis, a feature which is shared with the living G. biloba. In general, the size of stomata is larger in extant Ginkgo leaves than in those of the fossils. [Copyright &y& Elsevier]