Dissertation Research: Fossil History of the Saxifragaceae sensu stricto and their Woody Relatives, Cretaceous to Pleistocene

康奈尔大学的威廉·克雷佩特博士和伊丽莎白·赫姆森女士获得了一笔拨款，用于审查被子植物（开花植物）萨克拉科（岩纹和其他观赏植物）以及相关属Ribes（醋栗和醋栗）和Itea（弗吉尼亚柳树）的化石历史。今天，这些植物主要生长在北半球的温带、北极和高山地区。将对已发表的沙棘化石进行重新评价，并对来自新泽西州的新沙棘化石进行描述。其中一些化石具有花结构的细节，这将使它们能够使用分支学进行分析，这是一种确定进化关系的数学技术，它具有重要意义，因为它可以比许多其他方法更精确地分析这些关系。这将有助于实现本项目的直接目标，即编制一份准确的沙棘化石记录。这一记录将用于研究诸如沙棘草何时何地起源，何时多样化，它们的生殖生物学如何随时间变化，以及它们如何实现目前的地理分布等问题。这也将影响我们目前对萨克斯类植物关系的理解，特别是考虑到最近的DNA证据表明，真正的萨克斯类植物比以前认为的要少。现存最大的进化谜团之一是被子植物的起源、关系和成功。这个群体的重要性，从其数量的丰富和经济、医学和生态意义上看，使得解决这个谜团成为一个重要的优先事项。这个项目在整个谜团的背景下是重要的，因为1)其中的许多过程可以概括为被子植物增殖和优势地位上升的历史方面；2)因为一些早期的工人认为沙棘植物是许多更先进的开花植物群体的祖先。

A grant has been awarded to Dr. William Crepet and Ms. Elizabeth Hermsen of Cornell University to review the fossil history of the angiosperm (flowering plant) family Saxifragaceae (rockfoils and other ornamentals) and the related genera Ribes (currants and gooseberries) and Itea (Virginia willow). Today, these plants occur primarily in temperate, arctic, and alpine zones of the Northern Hemisphere. Published reports of fossil saxifrages will be reevaluated and new fossil saxifrages from New Jersey will be described. Some of these fossils possess details of floral structure that will allow them to be analyzed using cladistics, a mathematical technique for determining evolutionary relationships, which is of great significance as it allows for more precise analysis of these relationships than many other methods. This will aid in the attainment of the immediate goal of this project, compilation of an accurate record of fossil saxifrages. This record will be used to study questions such as when and where saxifrages originated, when they diversified, how their reproductive biology has changed over time, and how they have acheived their current geographical distribution. It will also affect our present understanding of saxifragoid relationships, especially in light of recent DNA evidence that indicates fewer plants are true saxifrages than previously thought.One of the greatest remaining evolutionary mysteries concerns the origin, relationships, and success of the angiosperms. The vital importance of this group, demonstrated by their numerical abundance and their economic, medicinal, and ecological significance, makes solving this mystery a significant priority. This project is important in the context of the overall mystery because 1) many of the processes targeted within can be generalized to historical aspects of the angiosperm proliferation and rise to dominance and 2) because the saxifrages have been considered by some earlier workers as ancestral to many more advanced flowering plant groups.