DISSERTATION RESEARCH: Mammalian Distribution in the Late Cretaceous and Earliest Paleocene Western Interior of North America: Testing Provinciality Through Time

晚白垩纪至早古新世（第三纪）时代（7200万- 6000万年前）的洪泛平原和三角洲沉积物，在西部内陆海道横跨北美大陆撤退时形成，记录了哺乳动物进化的一个非凡时期。哺乳动物在白垩纪-第三纪（K/T）界线（66 MYA）存活并迅速多样化；许多其他动物种群在这一边界遭受了大规模灭绝。进化生物学、古生态学和生物地层学领域的许多问题可以通过对这一时期哺乳动物分布模式的理解来解决。最近对这些冲积平原沉积物中保存的哺乳动物化石的研究表明，在晚坎帕尼亚期（大约72亿年前），有明显的北部和南部动物群。在接下来的1200万年里，这些动物群是否保持了不同？如果没有，它们在哪些方面发生了变化？确定基本模式一直很困难，部分原因是地理信息数量庞大且分散，部分原因是人们对所讨论的动物之间的关系知之甚少。新的可用的计算工具将允许安妮·威尔在威廉·克莱门斯的监督下，第一次定量地解决这些问题。研究的第一阶段将解决在化石遗骸中发现的哺乳动物物种之间的系统发育关系问题，包括那些以前没有考虑过的物种之间的关系。新的假设将被纳入从整个西部内陆的化石遗址数据汇编而成的数据库。利用地理信息系统（GIS）识别这些地理、环境和分类学数据中的空间关联，研究人员将应用不同类型的分析，通常用于量化动物类群相似性或变异，并比较结果。这个项目将在三个方面使科学界受益：通过创建一个可供其他研究人员使用的数据库；通过比较不同的动物相似性测量；通过创建一个健壮的、可测试的、可访问的哺乳动物跨K/T边界分布模型。

9622771 CLEMENS Floodplain and delta sediments of Late Cretaceous to earliest Paleocene (Tertiary) age (72-60 Million Years Ago), laid down as the Western Interior Seaway retreated across the North American continent, document an extraordinary period of mammalian evolution. Mammals survived and rapidly diversified across the Cretaceous-Tertiary (K/T) boundary (66 MYA); many other groups of animals suffered mass extinctions at this boundary. Many questions in the fields of evolutionary biology, paleoecology and biostratigraphy can be addressed through an understanding of the patterns of mammalian distribution during this time period. Recent studies of fossil mammals preserved in these floodplain sediments indicate that during the Late Campanian (approximately 72 MYA) there were distinct northern and southern faunas. Did these faunas remain distinct in the 12-million year period following? If not, in what respects did they change? It has been difficult to identify basic patterns, partly because of the large and scattered amount of geographic information, and partly because the relationships among the animals in question are poorly understood. Newly available computational tools will allow Anne Wiel, under the supervision of William Clemens, to address these questions quantitatively for the first time. The first stage of the research will address questions of the phylogenetic relationships among the species of mammals identified in the fossil remains, including those among species that have not previously been considered. New hypotheses are to be incorporated in a database compiled from fossil site data from throughout the Western Interior. Using a Geographic Information System (GIS) to recognize spatial associations in this geographic, environmental, and taxonomic data, the investigators will apply different types of analyses commonly used to quantify faunal similarity or variation, and compare the results. This project will benefit the scientific community in three ways: by cre ating a database that will be made available to other researchers; by comparing different measures of faunal similarity; by creating a robust, testable, and accessible model of mammalian distribution across the K/T boundary.