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

小行星9420512 虽然开花植物（被子植物）现在主宰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。花的特征在建立被子植物所有类群之间的分类学关系中是重要的。它们还在很大程度上决定了授粉模式--生殖生物学和进化中的一个重要因素。因此，发现各种花部特征出现的时间方面将产生关于关键特征和关键适应的历史的重要数据。这些知识将帮助我们了解被子植物进化的关系和趋势，并提供对起源和辐射的洞察。 康奈尔大学的威廉·克里佩特博士和凯文·尼克松博士正在调查一个丰富的被子植物花化石组合，这些化石来自于新泽西收集的图伦时代的白垩纪沉积物。这些化石是不寻常的，因为它们的多样性和良好的保存。它们包括构成一系列花的特征的第一次出现的形式，如融合的花瓣，花粉和polyads中的粘丝，以及花药的修改。这些化石中的许多都呈现出现今已知的生活形式的特征，因此可能代表了对现代谱系进化有相当大影响的“缺失环节”。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特征的外观。这些模式可能被证明是有用的，在评估广泛的假设被子植物之间的关系，并在评估传粉者特异性的演变趋势。 ??

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. ??