THE FOSSIL RECORD OF VERTEBRATE COPROLITES IN THE UNITED STATES

North America has the largest and most studied record of vertebrate coprolites. The first American coprolite was described in 1830 from the Upper Cretaceous of New Jersey and it probably represents Liassocopros.

The oldest significant coprofaunas are from three paleoenvironments in the upper Paleozoic: (1) black shales (e.g., Pennsylvanian of Illinois); (2) lagoonal shales (e. g., Pennsylvanian of New Mexico); and (3) redbeds (e. g., Lower Permian of Texas and New Mexico). The majority of these coprolites are interpreted as derived from fish.

Triassic redbeds of the Southwest and lacustrine shales of the Newark Supergroup contain a significant number of vertebrate coprolites. Redbed coprolites increase in abundance and diversity into the Upper Triassic. The majority of coprolites continue to pertain to fish, but terrestrial reptile coprolites (e.g., Dicynodontocopros) become more common in the Upper Triassic. Jurassic and Cretaceous nonmarine strata yield tetrapod coprolites, including theropod and crocodylian specimens, but they are relatively uncommon.

Coprolites are locally common in Paleogene fluvial strata of the western United States and abundant in the lacustrine units of the Eocene Green River Formation of Utah, Wyoming and Colorado. The upper Eocene/lower Oligocene White River Group, notably in South Dakota, contains large coproassemblages derived from terrestrial mammals. Pleistocene caves of Arizona, Utah and Nevada and New Mexico contain large deposits of the dung of mammals, including ground sloth, mammoth, mountain goat and Bighorn sheep. Human coprolites are known principally from caves in the desert Southwest and West as well as the southeastern United States.

The coprolite record in the United States has six acme zones: (1) Pennsylvanian (2) Early Permian; (3) Late Triassic; (4) early Eocene; (5) late Eocene-early Oligocene; and (6) Pleistocene. The application of binomial nomenclature has demonstrated the utility of coprolites for biostratigraphy and biochronology of the Permian and Triassic.