The Pleistocene Mammalian Fauna and Paleoenvironment of the Villa Grove Paleontological Site, Colorado

Abstract

Excavations of a gravel pit in 2011 and 2012 near the town of Villa Grove in the San Luis Valley of Colorado yielded several Pleistocene megafauna and small mammal fossils. We describe and analyze the fauna from the site and illustrate how this assemblage provides insights into Colorado high-altitude basin ecosystems during the Late Pleistocene. Extant taxa from the site include Brachylagus idahoensis, Cynomys cf. gunnisoni, Lemmiscus curtatus, Lepussp., cf. Sylvilagus nuttallii, and Urocitellus sp. Extinct taxa recovered include Camelops sp., Canis dirus, Equus cf. conversidens, and Mammuthus columbi. An unidentified species of Bison likely constitutes an extinct species, and Brachylagus idahoensis and Canis dirus are the first fossil occurrences of these taxa in Colorado. The genera Brachylagus, Lemmiscus, and Urocitellusare currently found in northern Colorado but not in the San Luis Valley. The fossil assemblage suggests that a sage brush-prevalent plains environment persisted in this region during the Wisconsin anglaciation, possibly comparable to that of the Great Basin.