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

非海洋软体动物是北美西部白垩纪上部和古新世大陆地层中丰富的大型动物化石。然而，它们的生物年代学潜力尚未实现，主要原因是缺乏对厚层序中分类群的生物地层范围的研究，这些研究是由化石哺乳动物的相关性暂时控制的。本研究将构建大平原北部兰西亚（上白垩纪）、普尔坎（Puercan）、托雷约尼安（Torrejonian）和蒂夫尼亚（Tiffanian）（分别为下、中、上古新世）地层的生物地层学和生物年代学分区。项目将由以下部分组成：1)野外工作，对威利斯顿盆地（蒙大拿州/北达科他州）的Hell Creek组和Powder River盆地（蒙大拿州/怀俄明州）的Lance组已知的Lancian时代地点进行地层组织；2)野外工作，在Fort Union群的下部发现了相对罕见的Puercan和Torrejonian时代的贝类地点；3)对白垩纪上部和古新世的软体动物进行一般分类研究，为分类群的鉴定提供框架；4)对科内的特定分类群进行详细的分类研究，这对北部大平原的生物地层学和生物年代学的目的特别有用。//

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.//