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

9420512尽管开花植物(被子植物)现在主导着地球的陆地生态系统，但关于它们的起源、系统发育关系和进化辐射模式仍然存在疑问。特别重要的是花本身的历史。花的特征对于建立被子植物所有类群之间的分类关系是很重要的。它们还在很大程度上决定了授粉方式--生殖生物学和进化中的一个重要因素。因此，发现各种花特征的出现时间的方面将产生关于关键人物和关键适应的历史的重要数据。这些知识将帮助我们理解被子植物进化中的关系和趋势，并为我们提供对起源和辐射的洞察。康奈尔大学的威廉·克雷特博士和凯文·尼克松博士正在研究一组丰富的被子植物花化石，这些花来自新泽西州收集的图罗尼亚时代的白垩纪沉积物。这些化石非同寻常，因为它们的多样性和良好的保存。它们包括构成一系列花卉特征的第一次出现的形式，如融合的花瓣、花粉和多倍体中的粘质线，以及花药修饰。这些化石中的许多呈现了从今天的生物形式中已知的特征的马赛克，因此可能是对目前血统的进化有相当大影响的“缺失的环节”。化石研究将记录现有谱系的最小年龄，并将有助于理解与各种授粉模式相关的花卉特征的外观。这些模式在评估被子植物之间关系的广泛假说和评估传粉者专一性的进化趋势方面可能被证明是有用的。?？

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. ??