UPDATES AND OVERVIEW OF THE TAPHONOMY OF THE AARON SCOTT QUARRY (MORRISON FORMATION, JURASSIC PERIOD) CENTRAL UTAH

The Aaron Scott Quarry (Morrison Formation, Jurassic Period) preserves the remains of multiple taxa including the disarticulated remains of Barosaurus and isolated elements of Glyptops, Opisthias, Eutretauranosuchus, Allosaurus, Coelurus, Camarosaurus, Dryosaurus, Stegosaurus and a Tricondontia. The bones show a range of weathering from no weathering to highly weathered and includes numerous bone fragments. The remains are preserved in a regressive sequence of a delta that is prograding into a lake. Evidence of the fluvio-lacustrine environment is supported by both stratigraphic and taphonomic data. Sedimentologically, the quarry is distinct from the paleosols that comprise the majority of the Brushy Basin Member of the Morrison Formation. Clay rip-up clasts are present at the base of the quarry and no evidence of bioturbation is present. Rare earth element analysis of bones indicates that bones that are more weathered and fragmented have a fluvial signature while the more complete and better preserved bones have a lacustrine signature. Data suggests that a delta had formed at the mouth of a river where it flowed into a lake with a depth of approximately 30m. The lake level lowered as a response to drought conditions, which caused animals to congregate near the lake over a period of time. Eventually the lake level rose, burying the bones.