Phylogeny of Coniferophytic Seed Plants

在维管植物的主要类群（蕨类植物、裸子植物、被子植物）中，针叶树和它们的亲密盟友（裸子植物）有广泛的化石记录，至少可以追溯到3亿年前，而且储量丰富，有时足以生产煤炭。尽管有丰富的材料基础，但化石针叶树及其近亲的文献记录往往很差，文献报告侧重于孤立或分离的植物部分，但很少整合所有可用的材料。俄亥俄大学的古植物学家Gar Rothwell和Gene Mapes正致力于改进古针叶树及其近亲的许多关键分类群的全植物重建，其基础是他们积累的材料以及几个国家博物馆收藏的研究标本。有了从营养和生殖结构中收集的特征数据，研究人员可以开始解决在更广泛的化石祖先背景下重建所有现存针叶树、杉科植物及其近亲（苏铁、银杏）的系统发育历史的长期目标。最近对裸子植物分子（DNA）的发现和解剖形态特征的重新分析，极大地改变了我们对几个裸子植物类群的进化关系的认识，如红豆杉属（紫杉醇的来源）和生藤属。对大量化石属的研究，目前仅从分散的植物部分中了解，将提高我们对裸子植物随着时间的推移而多样化的理解，并有助于对种子植物之间的谱系关系作出强有力的假设。

9527920 Rothwell Of the major groups of vascular plants (ferns, gymnosperms, angiosperms), the conifers and their close allies (gymnosperms) have an extensive fossil record extending back at least 300 million years, and in deposits rich enough at times to produce coal. Despite this rich base of material, fossil conifers and relatives are often poorly documented, with literature reports focusing on isolated or disarticulated plant parts but rarely integrating all material available. Paleobotanists Gar Rothwell and Gene Mapes of Ohio University are working to improve whole-plant reconstructions of numerous critical taxa of ancient conifers and relatives, on the basis of material accumulated by them as well as of specimens to be studied in museum collections in several countries. With character data amassed from both vegetative and reproductive structures, the researchers can begin to address the long-term goal of reconstructing the phylogenetic history of all the living conifers, taxads, and relatives (cycads, Ginkgo) in the wider context of their fossil ancestors. Recent molecular (DNA) findings and reanalysis of anatomical and morphological features have changed dramatically our understanding of the evolutionary relationships of several gymnosperm groups like the genus Taxus (source of taxol) and the Gnetophytes. Studies of numerous fossil genera, known at present only from scattered plant parts, will improve our understanding of gymnosperm diversification through time, and contribute to robust hypotheses about lineage relationships among the seed plants.