Biochronology and Evolution of Latest Cretaceous and Paleocene Nonmarine Mollusca of the Northern Great Plains

非海洋软体动物是丰富的动物宏体化石， 西部白垩纪和古新世最上层陆相地层 北美 然而，它们的生物年代学潜力， 主要原因是缺乏对以下问题的研究： 在厚层序中的生物地层范围 在时间上受与哺乳动物化石相关性的控制。 的 拟议的研究将建立一个生物地层学和生物年代学 Lancian（最早白垩纪）、Puercan、Torrejonian 下、中、上古新统地层 在北方大平原 该项目将包括 以下部分：1）野外工作，以地层组织已知的 威利斯顿海溪组的兰西亚时代地点 盆地（蒙大拿州/北达科他州）和粉地中的Lance地层 河流域（蒙大拿州/怀俄明州），2）实地考察以发现普坎 和Torrejonian年龄的软体动物地点在较低的部分， 福特联合集团，这仍然相对罕见，3）一般 白垩纪和古新世最上层软体动物的分类研究 为分类单元的鉴定提供一个框架，以及4）详细 对科内某些似乎是 特别适用于生物地层学的目的， 北方大平原的生物年代学。//

Nonmarine molluscs are abundant animal macrofossils of uppermost Cretaceous and Paleocene continental strata in western North America. Their biochronologic potential, however, has yet to be realized due primarily to the lack of study focused on biostratigraphic ranges of taxa in thick sequences of strata temporally controlled by correlation with fossil mammals. The proposed study will construct a biostratigraphic and biochronologic zonation of Lancian (uppermost Cretaceous), Puercan, Torrejonian, and Tiffanian (lower, middle, upper Paleocene, respectively) strata in the northern Great Plains. The project will consist of the following parts: 1) Field work to stratigraphically organize known Lancian age localities in the Hell Creek Formation of the Williston Basin (Montana/North Dakota) and the Lance Formation in the Powder River Basin (Montana/Wyoming), 2) field work to discover Puercan and Torrejonian age mollusk localities in the lower portion of the Fort Union Group, which remain relatively uncommon, 3) general taxonomic study of the uppermost Cretaceous and Paleocene mollusks to provide a framework for taxon identification, and 4) detailed taxonomic study of selected taxa within families that appear to be particularly useful for purposes of biostratigraphy and biochronology in the northern Great Plains.//