PRELIMINARY REPORT ON LATE PLEISTOCENE VERTEBRATES FROM LAKE MEAD NATIONAL RECREATION AREA, MOJAVE DESERT, SOUTHERN NEVADA

Vertebrate fossils of late Pleistocene age were first identified near Glendale, Nevada by National Park Service personnel during surveys in 1937-38 in what is presently Lake Mead National Recreation Area. This assemblage was not previously described; only remains of snapping turtle (Cheledra serpentina) from the site were reported in any detail. The collection was housed for many years at the Laboratory of Paleontology, University of Arizona, Tucson, but was recently transferred to the Quaternary Sciences Department, Northern Arizona University, Flagstaff. Examination and analysis of the fauna was initiated in 2003 and is ongoing.

The assemblage was recovered from gypsum-rich lacustrine and floodplain sediments in Meadow Valley Wash, associated with a radiocarbon date of >38,500 +/- 500 ybp. The most common animal in the mammal fauna is Castor canadensis (beaver), represented by several dozen fossils and at least seven individuals including juveniles, subadults and adults. The large mammal fauna consists primarily of postcranial remains; fossils of Odocoileus are numerically most common, followed in decreasing abundance by remains of Ovis, Camelops, Mammuthus, and Equus. Camelops is represented by a minimum of two individuals; for the remaining large mammals, the MNI=1. Small mammals from the site include Thomomys, Peromyscus, Microtus, and Neotoma. Fossils of amphibians, reptiles and birds are also preserved from the site.

In southern Nevada and the eastern Mojave Desert, late Pleistocene lacustrine faunas with diverse species representation and abundant, well-preserved bones are rare (exclusive of the Tule Springs complex in North Las Vegas). Because of this, the vertebrate assemblage from Lake Mead National Recreation Area provides a unique source of data for studying and understanding late Pleistocene depositional and paleoenvironmental regimes in this region