The fossil record of angiosperms has more potential than ever for contributing to the resolution of major questions in the evolution of the flowering plants due to the better understanding of the significance of leaf and pollen records and because of the increasingly complete and informative fossil record of flowers. Nonetheless, the record has fallen short of its potential (and of its potentially synergistic value) because, although it is better understood than ever, there are still problems in identifying fossils' affinities that have not been fully resolved and that have major implications with respect to determining timing in angiosperm evolution with either molecular clock–based models or minimum-age node mapping. This issue is of particular significance with respect to early angiosperm radiation, where more careful studies of existing specimens seem to have unrealized value for increasing our comprehension of floral evolution and homology, potentially in the context of strides in understanding MADS-box genes. Subjective methods with typological overtones are still often used in identifying fossils, even though phylogenetic context is available. Identification using phylogenetic context, among other things, does not obscure relative character changes within monophyletic groups, does not lend itself to facultative interpretation of affinities to suit outcomes of various models, and, thus, does not impede our understanding of angiosperm evolutionary history. Nonetheless, a reasonably good fossil record of angiosperms is emerging from the combined efforts of many laboratories and, when carefully evaluated, reveals an interesting and possibly informative pattern of flowering plant evolution. One of its most striking aspects is the rapid radiation of angiosperm taxa that are now unusually diverse around two particular times in geological history: the Turonian and Early Tertiary. Possible reasons for these intervals of rapid radiation among angiosperms will be discussed.
Annals of the Missouri Botanical Garden
Vol. 95 • No. 1
Vol. 95 • No. 1