Albright, L. B. III, ed., 2009. Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne. Museum of Northern Arizona Bulletin 65, Flagstaff, Arizona. THE DIAMOND VALLEY LAKE LOCAL FAUNA: LATE PLEISTOCENE VERTEBRATES FROM INLAND SOUTHERN CALIFORNIA KATHLEEN SPRINGER, 1* ERIC SCOTT, 2 J. CHRISTOPHER SAGEBIEL, 3 AND LYNDON K. MURRAY 4 1 Division of Geological Sciences, San Bernardino County Museum, 2024 Orange Tree Lane, Redlands, California 92374; kspringer@sbcm.sbcounty.gov 2 Division of Geological Sciences, San Bernardino County Museum, 2024 Orange Tree Lane, Redlands, California 92374; escott@sbcm.sbcounty.gov 3 Division of Geological Sciences, San Bernardino County Museum, 2024 Orange Tree Lane, Redlands, California 92374; jsagebiel@sbcm.sbcounty.gov 4 J. J. Pickle Research Campus, University of Texas at Austin, 10100 Burnet Road, Austin, Texas 78758- 4445; lkmurray@mail.utexas.edu ABSTRACT–The Diamond Valley Lake fauna is the largest open, non-asphaltic late Pleistocene assemblage known from the American southwest. A classic suite of Rancholabrean vertebrates characterizes the fauna, which includes nearly 100,000 identifiable fossils representing more than 105 vertebrate, invertebrate, and plant taxa from 2646 localities. Because of the volume, diversity, and excellent preservation of fossils recovered, this assemblage warrants designation as a local fauna. Located within the northern Peninsular Range physiographic province of southern California, the Diamond and Domenigoni Valleys are bounded by bedrock highlands and form a contiguous east-west drained trough, 9 km long and 2.5 km wide. The alluvium-filled valleys contain bedded silts and clays intercalated with coarse-grained channel fill representing a braided stream environment, which yielded AMS dates from ~19 ka to ~13 ka. These fluvial sediments unconformably truncate silts, clays and an organic black clay at depth. The clay is lacustrine in origin, with AMS dates from ~46 ka to ~41 ka. Both of these distinct sediment packages yielded abundant vertebrate remains; the lacustrine sediments produced a rare floral assemblage, as well. The relative abundance of Bison and Equus in the fauna resembles that reported from Rancho La Brea, while representation of Camelops approximates that from Mojave Desert localities. The rare co-occurrence of Paramylodon harlani, Megalonyx jeffersonii, and Nothrotheriops shastensis is also notable. Remains of Mammut americanum are abundant, far more so than at any other regional late Pleistocene site, and include very large individuals compared to other mastodons in the American West. Large carnivorans are rare, suggesting an unbiased distribution for the sample population. Pollen data indicate grassland, scrub, chaparral, forest, and riparian communities present in older sediments, while younger fluvial sediments suggest a forest/chaparral mosaic. INTRODUCTION Late Pleistocene vertebrate fossils are relatively abundant in the sediments of southern California, particularly from coastal regions (Miller, 1971; Stock and Harris, 1992) and the Mojave Desert (Jefferson, 1991; Scott and Cox, 2008). The fossil record of the region for this time period is dominated by the colossal late Pleistocene fossil assemblage from the Rancho La Brea asphalt deposits in Los Angeles, California. Boasting more than three million fossils representing over 640 species of vertebrates, invertebrates, and plants, Rancho La Brea is the single richest concentration of late Pleistocene terrestrial fossils known (Shaw and Quinn, 1986; Stock and Harris, 1992). Perhaps because of the numerous intensive and detailed investigations conducted over the past century at Rancho La Brea, the late Pleistocene fossil record from elsewhere in southern California has received less thorough attention. Miller (1971) described and analyzed in detail several late Pleistocene vertebrate faunas from the Los Angeles Basin, exclusive of Rancho La Brea, but this study is somewhat exceptional in this respect. Other late Pleistocene vertebrate faunas from the Mojave Desert (e.g., Jefferson, 1991) and from inland southern California valleys (e.g., Reynolds and Reynolds, 1991) have been incidentally reported, with published records generally consisting of faunal lists with little or no 217