Morphology and metrics, isotopes and dates: determining the validity of Equus laurentius Hay, 1913

ABSTRACT

Direct radiocarbon dating and stable isotope and biometric analyses are evidence that the holotype of Equus laurentius Hay, 1913 comprises the skull and jaw of two different horses that are less than 500 years old. The size and morphology of the specimens fall within the range of like elements of modern Equus caballus Linnaeus, 1758. The mandibular cheek teeth exhibit bit wear, demonstrating that the mandible is that of a domestic animal. The taxonomy of the purportedly late Pleistocene species is therefore resolved, and Equus laurentius Hay is a junior synonym of Equus caballus Linnaeus. Equus laurentius and its holotype are neither taxonomically nor phylogenetically pertinent to studies of North American Pleistocene Equus.

ACKNOWLEDGMENTS

Funding for the AMS dates was provided by National Science Foundation grant NSF EAR 91–18683, the Denver Museum of Nature and Science, Stafford Research Laboratories, and Mary Scott of Carmel, California. Access to comparative samples of Equus “occidentalis” from Rancho La Brea was provided by Christopher A. Shaw of the George C. Page Museum and Kevin L. Seymour of the Royal Ontario Museum. The authors thank Kim Scott of the Department of Biology, California State University, San Bernardino, as well as Kathleen Springer and J. Christopher Sagebiel of the San Bernardino County Museum, for critiquing portions of this study. The manuscript was reviewed by two anonymous reviewers who are thanked for their efforts. David Anthony of the Institute of Ancient Equid Studies, Department of Anthropology, Hartwick College, New York, is thanked for his comments and observations regarding bit wear in ancient horses.