Fossil Dung

Source: Mead, Jim I., "Quaternary of the Colorado Plateau," a book chapter in press, and other material from the literature.

Fossil dung deposits (a.k.a. coprolites, or boluses) are usually rare in the Southwest, but by far the largest and most numerous deposits have come from Pleistocene mammals that once lived on the Colorado Plateau. Most of the localities have been discovered and studied only since 1983. Besides revealing information about the diet of ancient species, these remains also provide high-quality organic residues for radiocarbon dating. Further biochemical analysis of fossil dung deposits is expected to yield a wealth of dietary, climatic, and extinction data.

Analysis of dung deposited by extinct or extirpated megafauna in the Southwest began with Lull's (1930) description of Nothrotheriops shastensis (Shasta ground sloth) boluses found in Rampart Cave in Grand Canyon in Arizona. Not until detailed examination of the dung deposits for clues to megafaunal extinction by Martin et al. (1961) did the analysis of fossil dung become an integral past of paleoecological reconstructions on the Colorado Plateau. Analysis of coprolites for dietary contents was perfected by Hansen (1978; 1980).

One of the world's most remarkable deposits of large boluses were the over 300 square meters  of mammoth dung found in Bechan Cave in southern Utah. These boluses contained well-preserved plant macrofossils. As much as 95% of its composition consisted of grass remains, which proved that mammoths on the Colorado Plateau, like the modern elephants of the old world, ate large quantities of grass. Remains of saltbush, sagebrush, birch, blue spruce and other woody plants made up the rest of the fossil dung.

At least 20 localities from the Colorado Plateau are known to contain desiccated dung of extinct and extirpated megaherbivores. Mead and Agenbroad (1992) provide a recent in-depth review of radiocarbon dates and dietary analyses conducted on late Quaternary extinct and extant megaherbivores of the Plateau, including a locality by locality review of available data. Of the seven species of megaherbivore identified using dung, four became extinct sometime between 11,800 and 11,000 yr B.P.: Harrington's mountain goat, shrub ox, mammoth, and Shasta ground sloth.

Davis, O. K., L. D. Agenbroad, P. S. Martin, and J. I. Mead. 1984. The Pleistocene dung blanket of Bechan Cave, Utah. Carnegie Museum of Natural History Special Publication: 267-282.

Hansen, R. M. 1978. Shasta ground sloth food habits, Rampart Cave, Arizona. Paleobiology 4: 302-319.

Hansen, R. M. 1980. Late Pleistocene plant fragments in the dungs of herbivores at Cowboy Cave. Pp. 179-189 In: J. D. Jennings, editor. Cowboy Cave.   Anthropological Papers, vol. 104, University of Utah, Provo, UT.

Lull, R. S. 1930. The ground sloth, Nothertherium. American Journal of Science 22: 344-352.

Martin, P. S., B. E. Sabels, and D. Shutler. 1961. Rampart Cave coprolites and the ecology of the Shasta Ground Sloth. American Journal of Science 259: 102-127.

Mead, J. I., L. D. Agenbroad, O. K. Davis, and P. S. Martin. 1986. Dung of Mammuthus in the arid southwest, North America. Quaternary Research 25: 121-127.

Mead, J. I., M. K. O'Rourke, and T. M. Foppe. 1986. Dung and diet of the extinct Harrington's mountain goat (Oreamnos harrintoni). Journal of Mammology 67: 284-293.

Mead, J., I., and L. D. Agenbroad. 1992. Isotope dating of Pleistocene dung deposits from the Colorado Plateau. Radiocarbon 34: 1-19.