PALEOECOLOGY OF A RANCHOLABREAN COMMUNITY PRESERVED IN FLOODPLAIN DEPOSITS OF MEADOW VALLEY WASH, LINCOLN COUNTY, NEVADA

This study involves fossiliferous exposures in a gravel quarry owned by Jim Wilkin near Panaca, Nevada. Previous sedimentological studies have shown that the site represents fluvial deposits of an abandoned floodplain of Pleistocene Meadow Valley Wash. The biota includes freshwater gastropods (collected from pockets of fine-grained sediment), pollen and plant fragments, tusk material (probably from Columbian mammoth), and a horn core and skull fragments from Bison latifrons. While no radiometric dates have yet been obtained, the presence of Bison material constrains this deposit to the Rancholabrean land mammal age.

This is not a typical late Pleistocene Great Basin biota. While Bison antiquus is relatively common within the late Pleistocene of Nevada, B. latifrons is very rare. Pollen analysis shows the presence of a highly diverse flora including, among other taxa, Larrea, Alnus, Pinus, Quercus, and Artemesia. It is surprising to find Larrea and Artemesia co-occurring with Alnus.

To better characterize the paleoecology of this deposit, and to place it within the context of other Rancholabrean sites in the Southwest, future work will include carbon and oxygen stable isotopic analyses of enamel from B. latifrons and M. columbi to address questions of diet and climate, additional pollen and macrofloral analyses to address questions concerning the co-occurrence of Alnus and Larrea, radiometric dating of bone material and snail shells, and examination of other exposures of these deposits in the region.