Paleofloristics Data for the Study of Global Change and Biotic Extinctions

将对落基山脉南部的被子植物叶大化石进行调查，以确定白垩纪-第三系界线(6600万年前)的植物组合中的属和科多样性模式，白垩纪-第三系是生物史上五个主要灭绝时期之一。尽管对花粉和叶片组合的物种水平分析已经阐明了目前气候和生态变化的许多细节，但许多植物灭绝的生物学特性无法准确确定，因为必须通过对保存完好的遗骸中的叶片脉络和角质解剖的详细分析，以及与现存被子植物叶片的参考标本进行广泛的比较来确定叶片大化石。这一分析将提供比目前在具有严格地层年龄控制的组合中的晚白垩世和最早第三纪古植物群更可靠的系统关系确定。这些系统的测定将为未来白垩纪末植物灭绝的定量分析提供数据基础，这对于检验关于生物灭绝性质的假说将是重要的。

Angiosperm leaf megafossils from the southern Rocky Mountains will be surveyed to determine patterns of generic and familial diversity in floral assemblages bracketing the Cretaceous-Tertiary boundary (66 million years b.p.), one of the five major extinction episodes in the history of life. Although species-level analyses of pollen and leaf assemblages have elucidated many details of climatic and ecological change at this time, many biological properties of plant extinction cannot be determined accurately, because leaf megafossils must be determined through detailed analysis of foliar venation and cuticular anatomy in well-preserved remains and extensive comparisons with reference collections of extant angiosperm leaves. This analysis will provide more reliable determinations of systematic relationships than are currently available for latest Cretaceous and earliest Tertiary paleofloras, in assemblages that have tight stratigraphic age control. These systematic determinations will provide a data base for future quantitative analysis of end-Cretaceous plant extinction, which will be important for testing hypotheses on the nature of biotic extinction.