Structure, Systematics, and Phylogenetic/Evolutionary Significance of Upper Cretaceous (Turonian) Angiosperm Flowers

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9420512 Crepet Although flowering plants (angiosperms) now dominate Earth's terrestrial ecosystems, there remain questions about their origins, phylogenetic relationships, and patterns of evolutionary radiation. Of particular significance is the history of the flower itself. The characteristics of flowers are important in establishing taxonomic relationships among all the groups of angiosperms. They also determine, to a great extent, the modes of pollination--an important element in reproductive biology and evolution. Thus, discovering aspects of the timing of appearance of various floral characteristics would yield important data on the history of key characters and of key adaptations. This knowledge would help us understand relationships and trends in angiosperm evolution and provide insight into origins and radiations. Dr. William Crepet and Dr. Kevin Nixon of Cornell University are investigating a rich assemblage of fossil angiosperm flowers from Cretaceous deposits of Turonian age collected in New Jersey. These fossils are unusual because of their diversity and their excellent preservation. They include forms that constitute the first appearances of an array of floral characters such as fused petals, viscin threads in pollen and polyads, and anther modifications. Many of these fossils present a mosaic of features known from living forms of today, and thus may represent "missing links" that have considerable bearing on evolution of present lineages. Fossil studies will document the minimum ages of existing lineages and will contribute to understanding the appearance of floral features associated with various modes of pollination. These patterns may prove useful in evaluating broad hypotheses of relationships among angiosperms and in evaluating trends of evolution in pollinator specificity. ??