VERTEBRATE ICHNOFOSSILS FROM THE UPPER JURASSIC STUMP TO MORRISON FORMATIONAL TRANSITION--FLAMING GORGE RESERVOIR, UT

The United States Bureau of Reclamation commissioned the Utah Geological Survey to organize a preliminary survey for paleontological resources along the shoreline of Flaming Gorge Reservoir in northeastern Utah in the spring of 2002. During that work, the authors discovered sauropod trackways on a vertical sandstone cliff of the uppermost Stump Formation. Closer investigation of the strata revealed not only the under tracks of a small adult sauropod but a trackway representing a juvenile sauropod as well. In addition, there are well-preserved casts of sauropod manus and pes prints weathering from an overlying dinoturbated horizon. Approximately 4 m below the sauropod tracks, there are a series of thin-bedded, ripple-marked sandstone units with several pterosaur trackways preserved as well as a small quadrapedal trackway. These tracks are preserved in marginal marine deposits along the retreating shoreline of the Sundance Seaway that interfinger with the fluvial and overbank units of Salt Wash Member of the Morrison Formation in northeastern Utah. The typical fluvial crossbedded sandstone units of the Salt Wash Member are well exposed a couple of meters above the sauropod trackway.