LUDTKE, J.A. *; PROTHERO, D.R.; San Diego State University; Occidental College: Taxonomic Revision of the Middle Eocene Protoceratid Leptoreodon (Mammalia: Artiodactyla)

The primitive hornless protoceratid Leptoreodon occurs abundantly in the Uintan (Utah, California, Saskatchewan, Texas, Wyoming, and Montana) and rarely in the Duchesnean (California, Texas and Saskatchewan) North American Land Mammal Ages. Large new collections of Leptoreodon from the middle Eocene rocks of San Diego County, California prompted a re-examination of the systematics of the genus. Early Uintan localities yield the large type species, L. marshi, the largest species, L. major, and the diminutive species L. pusillus. Late Uintan localities produce all seven known species: the rare L. edwardsi, the large L. stocki, the sharp-crested L. leptolophus, along with early Uintan survivors L. major, L. marshi, L. pusillus, and a new species, L. golzi, morphologically similar to L. leptolophus but distinctly smaller in size. Early Duchesnean localities yield small collections of L. leptolophus, L. golzi, L. pusillus, and L. stocki. Unrecognized sexual dimorphism is not a source of any of these species, as this mainly affects the upper canines, which were not measured for data purposes. When faced with this small plethora of species, statistical analyses were conducted to complement the morphological basis for identifying species. All seven species remained distinct, suggesting that similarly-sized species inhabited different regions as a response to intraspecific ecological competition.