A New K-T Boundary Locality in the Denver Basin, Colorado
BARCLAY, Richard S., Denver Museum of Nature and Science, 2001 Colorado Boulevard, Denver, CO 80205-5798, [email protected]; DILCHER, David L., Division of Paleobotany, Florida Museum of Natural History, P.O. Box 7800, Gainesville, Florida, [email protected]; and JOHNSON, Kirk R., Denver Museum of Nature and Science, 2001 Colorado Boulevard, Denver, CO, [email protected]

A new, continuous, and highly fossiliferous K-T boundary locality in West Bijou Creek, located in the eastern portion of the Denver Basin of Colorado has been discovered. Exposures of this new boundary section are locally excellent, and fossils are abundant and diverse including plant megafossils, pollen, vertebrates, and invertebrates. Localities with well-preserved plant material are common in the Paleocene portion, and are conveniently located in horizontally continuous layers at several stratigraphic levels. This allows for analysis of both lateral variation of plant assemblages on a floodplain, as well as temporal changes in the plant megafossils during the very earliest Paleocene.

The West Bijou Creek localities will be extensively sampled and studied to determine aspects of the diversity during the very earliest Paleocene. Examination of biodiversity patterns in the West Bijou Creek boundary flora will be used to make comparisons to other basal Paleocene sections in the Denver Basin.

The West Bijou Creek K-T boundary locality lies only 70 km from the South Table Mountain K-T boundary locality (Golden, Colorado), yet preliminary analyses show that they have only a small percent of morphotypes in common. The West Bijou Creek Paleocene flora appears to have more species in common with basal Paleocene floras in the Williston Basin of North Dakota (700 km distant) and from Ravenscrag, Saskatchewan (1,100 km distant) than to the South Table Mountain locality. Important questions can be answered with data from this new West Bijou Creek K-T boundary section. Intensive collection at new localities in the West Bijou Creek section are planned for this summer, adding new information to an already interesting set of data.