PLEISTOCENE VERTEBRATE FOSSILS FROM PINTO BASIN, JOSHUA TREE NATIONAL PARK, MOJAVE DESERT, SOUTHERN CALIFORNIA

The Pinto Basin in Joshua Tree National Park is a recognized but largely unexplored site for Quaternary fossil remains. Lacustrine exposures in this area have yielded abundant but fragmentary Pleistocene vertebrate fossils. Remains consist primarily of isolated dental and distal appendicular elements. Large and small horses and camels are most commonly represented, but specifically diagnostic fossils are rare.

New studies initiated by the San Bernardino County Museum (SBCM), in cooperation with the Joshua Tree National Park Association, focus on renewed recovery and preservation of vertebrate fossils as well as their geologic and taphonomic context. More than 100 discrete fossil localities have been identified since early 2002. Fossils recovered during this period are housed at the SBCM in preparation for eventual long-term curation at the Park. GPS data were acquired for all new localities, for inclusion in the Park’s digital overlay.

New discoveries include remains of Canis (wolf-sized) and an indeterminate proboscidean, both new records for the fauna. Teeth of extinct horses (Equus) exhibit morphology strongly suggestive of a Pleistocene age for the fossils; however, previous suggestions of a late Pleistocene (Rancholabrean) age are not supported at present. Most fossils occur as isolates, but some localized concentrations of fossils are indicative of more complete and extensive remains yet present in the subsurface.

Previous investigations in the region studied whether humans and extinct Pleistocene megafauna co-occurred in the area. The present study confirms the interpretation that Holocene artifacts present in Pinto Basin are associated with Pleistocene fossils because of deflation. Recommendations for future efforts to properly manage and conserve fossil resources include regular field inspection, ongoing laboratory analysis, and long-term preservation and storage in a federally recognized, accredited repository.