CONSTRAINING THE AGE OF THE EOCENE TALEGA BONEBED THROUGH MICROFOSSIL VERTEBRATE INDEX TAXA

The Talega Bonebed is the only Eocene bonebed in California, providing a unique window into the fauna of Western North America at this time. The Talega Bonebed was discovered in 1998 in San Clemente during a paleontological mitigation of a housing development. The 10 cm thick bonebed was deposited as an attritional deposit in a fluvial environment and is part of the Eocene-aged Santiago Formation. There are 46 jackets of the Talega Bonebed in the Orange County Paleontological Collection housed at the John D. Cooper Center. Despite the large amount of collected material and diversity of taxa discovered, the age of the Talega Bonebed is not well constrained. Most the larger vertebrate taxa are known across the Eocene fossil record of Southern California and are not useful in constraining the age the locality. The use of microfossil vertebrate taxa can better constrain of the Talega Bonebed, and rodents and primates are known from the site. For this reason, matrix from the bonebed was processed using screen washing and heavy liquid separation techniques to obtain more microfossil specimens in order to better constrain the age range of the Talega Bonebed. The microfossil taxa so far identified from the bonebed, such as Microparamys, Sespedectes, and Simimys, are typical of middle to late Eocene taxa from Southern California, but the occurrence of the California endemic primate, Dyseolemur pacificus, indicates that the bonebed can be constrained to the late Uintan (44-41.5 mya). Determining the age of the bonebed is important, as a more constrained age will aid in faunal comparisons to other Eocene sites from California. By recovering, identifying, and studying the small mammals from the Talega Bonebed a better reconstruction of the paleoenvironment of the Talega Bonebed can be hypothesized. Combined with additional faunal comparisons of Southern Californian Eocene localities, study of the Talega Bonebed may also lead to more precise reconstructions of the overall paleoenvironment and paleoecology of Eocene Southern California.