THE TULE SPRINGS LOCAL FAUNA: LATE PLEISTOCENE VERTEBRATES FROM THE UPPER LAS VEGAS WASH, CLARK COUNTY, NEVADA

The Tule Springs site, located in the upper Las Vegas Wash north of Las Vegas, Nevada, was the focus of episodic archaeological scrutiny from the 1930s through the early 1960s. These archaeological investigations concomitantly documented a diverse, regionally significant late Pleistocene fauna from ~25 localities. In the absence of any verifiable human-megafauna association, these studies were discontinued. Forty years later, renewed paleontologic field investigations by the San Bernardino County Museum have resulted in the discovery of hundreds of fossil localities and specimens throughout the upper Las Vegas Wash, greatly extending the geographic and temporal footprint of the original investigations. Based upon these new data, we recognize that the upper Las Vegas Wash encompasses the largest open-site Rancholabrean vertebrate fossil assemblage in the Mojave Desert and the southern Great Basin. This assemblage therefore warrants designation as a local fauna, named for the original Tule Springs site.

The large mammal assemblage is dominated by remains of Mammuthus columbi and Camelops hesternus. Metric and morphologic data indicate the presence of three distinct species of Equus and two species of Bison. Newly-recognized faunal components include the microvertebrates Rana sp., Anniella sp., Masticophis sp., cf. Arizona sp., Marmota flaviventris, Neotoma sp. cf. N. lepida, Reithrodontomys sp., and cf. Onychomys sp. The list of medium- and large-sized mammals is expanded to include Lynx rufus, a large bovid similar in size to Euceratherium, and the first definitive fossils of Bison antiquus. These latter fossils constitute the youngest reliably-dated Bison remains known from the Mojave Desert.

The depositional setting is a series of fine-grained ground water discharge deposits of the informally designated Las Vegas Formation. Seven stratigraphically-ascending units (A through G) have been recognized. Units B, D, and E were known to be fossiliferous in earlier studies; recent efforts confirm unit C is also sparsely fossiliferous. Radiometric and other dating techniques indicate the deposits span as much as the last 200 ka, and therefore encompass a sedimentary and faunal record of multiple climatic shifts between glacial and interglacial conditions, including the end-Pleistocene transition.