Phylogeny of Coniferophytic Seed Plants

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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.