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.
