Paleontology of nonmarine Cretaceous--not marine Triassic--limestone in the Salt anticline, southeastern Utah.
— Spencer G. Lucas, Kenneth K. Kietzke, and Thomas H. Goodspeed

A thin limestone in the Salt Valley, northeast of Moab, Utah, was assigned to the Early Triassic Sewemup Member of the Moenkopi Formation based on the supposed presence of juvenile specimens of the Smithian ammonoid Meekoceras. Most workers view this outcrop as the easternmost extent of the Sinbad Formation, and thus the eastern limit of the Smithian seaway. We collected silicified micro- and macrofossils from this unit. The planorbid freshwater gastropod Gyraulus veternus superficially resembles juvenile specimens of Meekoceras, and dominates the assemblage. Other macrofauna includes the gastropods Reesidella, Mesopyrgium, Physa and Zaptychius? and the bivalve Unio?. Microfossils are the charophytes Atopochara trivolvis and cf. Obtusochara and the ostracods Cypridea compta, Bisulcocypris persulata and Cyclocypris?. These fossils are clearly of freshwater origin and indicate an Early Cretaceous (Aptian) age. Age and lithology suggest the limestone in the Salt Valley is in the Cedar Mountain Formation. The easternmost extent of the Sinbad Formation is along the Colorado River in the Canyonlands, 39 km southwest of the Salt Valley.