STRATIGRAPHY, DEPOSITIONAL ENVIRONMENT, AND TAPHONOMY OF A MASS BONE BED IN THE JURASSIC MORRISON FORMATION, OJITO WILDERNESS, NEW MEXICO: EXPANDING OUR UNDERSTANDING OF NEW MEXICO FOSSIL LOCALITIES

To date, there have been few mass bone beds discovered within Jurassic strata in New Mexico. This study puts forth a newly discovered mass bone bed in the Brushy Basin Member of the Morrison Formation. The site lies in the Ojito Wilderness where fossils crop out in the Brushy Basin, Salt Wash, and Jackpile Members of the Morrison Formation. In the Ojito, the largest concentration of bones occurs on a thin mesa (0.013 km²) in the Brushy Basin Member. The mesa sediments represent a fluvial environment with a succession of floodplain mudstones and isolated channel/crevasse splay deposits capped at the mesa top by amalgamated channel sandstones and conglomerates. Bones commonly crop out just below or in the base of channel scours and concentrate in the amalgamated channel sandstones. Greater than 100 individual bones in cliff face exposures and eroded boulders surrounding the mesa include femur, rip, tibia, scapula, vertebrae, etc. likely from diplodocidae, allosauridae, and other families. Overall, this newly discovered site represents one of the most prolific bone beds in Jurassic strata in New Mexico and provides new opportunities to understand the biodiversity and geographic mobility of Jurassic-aged dinosaurs in New Mexico.