Description
The Coyote Badlands in northwestern Anza-Borrego Desert State Park, San Diego County, California is among three of the most fossil rich areas in the park. Only Ash Wash, a canyon on the northwestern edge of the badlands, has previously been described in terms of its stratigraphy and paleontology. The central Coyote Badlands, which contain numerous fossil localities, remains unstudied. Four stratigraphic sections were measured and correlated based on the presence of sedimentologically unique calcareous mudstone beds. The northwestern most of these sections contains an ash lens which is believed to be part of 759 ka Bishop Ash series, exposed in ash wash. In addition to a 250 meter thick composite stratigraphic section, a structural map was also produced for the badlands. This map presents the exposures of the correlative mudstone beds, bed attitudes and observed faults. An Irvingtonian Land Mammal age vertebrate fauna was collected prior to this study. The taxa within the fauna is identified and described in this study. The assemblage is restricted to mammals and include typical carnivores and herbivores for other North American lrvingtonian aged faunal assemblages. More rare Irvingtonian taxa from the fauna include Canis sp. cf. C. armbrusteri, Homotherium sp. cf. H. crenatidens, Tapirus merriami, and Paleolama. An analysis of the temporal ranges of all the taxa identified from the assemblage shows an overlap within the middle Pleistocene or late Irvingtonian. This age assignment corroborates the correlated 759 ka age for the ash in the section. The Coyote Badlands assemblage was compared to other late Irvingtonian faunal assemblages from western North America using three comparison coefficients. These other faunal assemblages include from southern California Ash Wash, Borrego Badlands, Vallecito Badlands, Bautista Creek, and Pauba Formation. Other assemblages compared are: Irvington, California; El Golfo, Sonora, Mexico; Curtis Ranch, Arizona; and Porcupine Cave, Colorado. The fauna was most similar to the Borrego and Vallecito Badlands. Lastly, an analysis of the sedimentololgy of the deposits and paleoenvironments for the fauna indicate a savanna-type habitat on an alluvial fan and braided stream depositional system.
