黔西滇东晚二叠世长兴期松柏类植物的分类学

Permian-Triassic is an important stage for the earth to evolving from Paleozoic to Mesozoic. In this period, the Western Guizhou-Eastern Yunnan of the upper Yangtze Platform in South China, located on the eastern margin of the Kangdian Massif, was generally in an offshore environment, receiving successively sediments of terrestrial - marine/terrestrial transitional - marine facies. The whole Permian and Triassic section is well preserved with well-developed biome, continuous strata and complete sequence, favorable for the study of the marine to terrestrial biostratigraphic boundary, their correlation and the floral replacement. .Based on the abundant and diversified fossil conifers newly discovered in the marine Xinmin and Duanshan sections, marine/terrestrial transitional Mide and Tucheng sections in this area, built some of the dominant plant assemblages of the Permian - Triassic floras in the world, the focus of this project is the study of these fossil conifers bearing in Late Permian Changhsingian Talung and the upper part of Xuanwei Formations. The contents of the study include: 1)Taxonomy - establishing the classified system of fossil conifers in South China according to the vegetative branches and leaves (long- and short- shoots, phyllotaxy, leaf shape, veining etc.),the microstructures of in situ and dispersed fossil cuticles, anatomical structure of fossil woods, the pollen cones (arrangement, pollen) and seed cones (bract scale and seed scale). 2) Evolutionary lines - on the basis of the classified system, comparing and contrasting botanical features of fossil conifers with the families and genera of the extant conifers, paying attention to the features with evolutionary significances (for example female cone, primary xylem, stele type etc.). 3) Paleoecology - combining sedimentology, floral taphonomy and other marine fauna and terrestrial plant fossils coexisted with fossil conifers, discussing its ecological habit and habitat. .The purposes of this study are: 1) establishing and perfecting the natural classified system and evolutionary lines of Late Permian Changhsingian fossil conifers; 2) resolving their ecological habit and habitat; 3) indicating the cause and pattern of the end-Permian terrestrial plant extinction, the co-evolutionary relationship between terrestrial plant and its environment.

黔西滇东地区发育的从海相到海陆过渡相再到陆相二叠纪-三叠纪界线剖面具有地层出露完整，沉积连续，动、植物化石丰富等优势，是解决由海到陆生物地层划分对比、研究植物群演替的关键地区。基于该地区海相新民剖面和断杉剖面、海陆过渡相密德剖面和土城剖面晚二叠世长兴期地层中发现的大量具有分类、生态和演化意义的松柏类植物化石新材料，利用其保存的植物体枝叶形态（营养枝、生殖枝、叶序、叶形和叶脉等）、解剖结构（角质层和木化石）和繁殖器官（大、小孢子叶球）等特征，并与现生松柏类植物科属特征进行比较，寻找古、今松柏类植物的中间类型，开展其植物分类学及演化谱系研究；结合沉积学、植物埋藏学和其伴生的生物关联分析，探讨它们的生态习性及其生成环境。其预期研究成果不仅可以解决长期以来困扰古植物学界的有关这类植物的性质、分类、演化和生态等问题，而且对揭示古生代松柏类部分科属灭绝的原因和陆地植物与环境的协同演化关系具有直接意义。

国家自然基金面上项目“黔西滇东晚二叠世长兴期松柏类植物的分类学”，在课题负责人的带领下，圆满完成了项目设计的各项工作。主要研究内容：（1）对松柏类植物化石的形态学做了详细地分析（枝叶形态、解剖学特征、繁殖器官特征等），并对其分类学问题做了深刻地讨论，得到了初步的成果。（2）对松柏类植物化石的角质层显微结构特征做了详细研究，并利用化石角质层的厚度、气孔密度、气孔指数和气孔比率等指标及Franks模型做辅助，成功找到了最近亲缘种，得到了可恢复当时古大气CO2浓度和古温度的数据，并定量重建了古大气CO2浓度。（3）根据古生物学（植物大化石、孢粉化石、叶肢介化石、双壳化石等）、沉积学特征、地球化学特征（有机碳同位素地球化学等）建立了华南二叠系-三叠系综合的地层对比格架，并以此为基础，深入研究了华南二叠纪-三叠纪之交古植物群的演变过程（灭绝和残存形式）。（4）本项目研究中深入与国外专家合作，通过对主干剖面的沉积学和化石埋藏学特征的研究，得到了华南陆相二叠系-三叠系中保存的沉积环境演变模型。