中国银杏目拜拉属植物化石及环境背景研究

中生代是银杏类植物最繁盛的时期，中国中生代陆相地层发育，保存有大量的银杏类植物化石；中生代也普遍被认为是温室气候。本项目以“化石植物生物学”和“微细构造与整体重建”的学术思想为指导，对我国新疆、内蒙、陕西、河南等地侏罗纪-早白垩世期间的银杏类拜拉属植物及其伴生植物化石开展全面研究，对已有和可能发现的新植物类型进行深入的比较形态解剖学研究，深入认识拜拉属植物的生物学特性，以及它们的系统分类和分异度情况；同时利用银杏类植物表皮角质层的气孔密度和气孔指数恢复古大气CO2浓度，结合地质年代学，使用两种不同的锆石铀-铅同位素年代学分析手段，对相关地层的植物化石层进行限定，确定不同时间节点古大气CO2浓度。综合植物形态解剖、角质层分析和植物群特点，获取拜拉属植物的古环境特点，探讨古大气二氧化碳浓度的变化规律及其与植物演化和环境背景的关系。

The genus Baiera (Ginkgoaleans) is an important Mesozoic fossil plants which has been recorded from the Late Permian. Since the middle of the 19th Century numerous ginkgophytes have been recorded from various geological horizons throughout the world. Ginkgoaleans markedly increased in morphological and taxonomical diversity until the Late Triassic, and continued to flourish into the Early Cretaceous before a marked decrease in diversity occurred at the end of that epoch. This group displayed a quite remarkable range of morphology and the acme of diversification in the Mesozoic. Although the Mesozoic terrestrial sediments of China bear abundant Baiera, little progress was made on the classification, phylogenetic relationship and the evolutionary history of this unique plant group until recent decades. Most fossil Baiera described are leaf-remains generally somewhat similar to the Ginkgo-shaped leaves in gross morphology, but they yield little anatomical information, and few reproductive organs have so far been found and identified. Although there are more than 31 species of Baiera recorded in China, a great number of them are insufficiently known, or even their generic attributions may be uncertain, especially for those fragmentarily preserved specimens. .Mesozoic is a typical greenhouse climate, the CO2 content was fluctuating rather than stable interrupted by several rapid changes of paleo-CO2 which associated with some geological events. Terrestrial plants have indicative effects on the change of environment. Some terrestrial vascular plants have been used to reconstruct palaeo-pCO2 by stomatal parameters analysis, and consequently the estimated results supplement and correct the long-term carbon cycle model. .It has become a primary goal of modern palaeobotany to study and reconstruct fossil plants in full in order to have a better understanding of palaeoecology, biology, development and phylogenetic relationships of fossil plants. This program will study the morphology, anatomy and palaeoenviroment of some Baiera from the Jurassic-Early Cretaceous of China by using modern techniques and methods, and all plants associated with Baiera will also be identified. Meanwhile Baiera and other Ginkgo-like leaves fossil from the Mesozoic of China will be used to reconstruct the palaeo-pCO2 of the Jurassic-Early Cretaceous. All the results will contribute much more to our knowledge of classification and phylogeny of Baiera and the relationship paleo-CO2 fluctuations and geological events, and provide the basis for biological, palaeoclimate and palaeoenvironmental interpretations.