HIGH ELEVATION MAMMUTHUS FROM THE FLORISSANT FOSSIL BEDS NATIONAL MONUMENT, COLORADO

The Florissant fossil beds are world renowned for the highly diverse assemblage of fossil plants and insects from lacustrine shales of the latest Eocene Florissant Formation, but fossils from the overlying Quaternary sediments are rare. New fragmentary material from a mandible and molar tooth of Mammuthus has been recovered near the visitor center for the Florissant Fossil Beds National Monument. The mammoth occurs in Pleistocene gravels, which comprise a thick alluvial fill.

The thickness of the enamel and lamellar frequency of the tooth suggest that the specimen should be referred to M. columbi rather than M. primigenius which was adapted to tundra conditions farther north.

The fossil material is significant for three reasons: (1) it provides documentation of the presence of mammoth fossils at Florissant, (2) this discovery at an elevation of 2550 meters also represents a relatively high elevation for Mammuthus, and (3) the tooth has been radiocarbon dated on purified collagen at 49,830 ± 3290 (CAMS-22182). Even though this date exceeds the reliable range for radiocarbon dating, it indicates that mammoths were at high elevations before the last glacial maximum (ca. 18,000 radiocarbon years ago). Throughout the western United States, mammoths are generally associated with other taxa indicative of open habitats that are quite different from the high elevation forests of today.