DINOSAUR-BEARING ONCOIDS FROM EPHEMERAL LAKES OF THE LOWER CRETACEOUS CEDAR MOUNTAIN FORMATION, UTAH

摘要

Here we document the occurrence of locally common oncoids in the Cedar Mountain Formation of Utah in the Woodside Anticline area of the San Rafael Swell and use them to understand changes in the Early Cretaceous landscape and their effects on the dinosaur fauna. Detailed facies analysis is required to understand the context of these changes within the broader patterns of Mesozoic tectonics and the fossil record. Oncolite crops out in the Cedar Mountain Formation, directly overlying the Buckhorn Conglomerate. Oncolite is not widely distributed outside of the Woodside Anticline area. The oncoids are found in a bimodal population with the majority in the 2–5-cm-diameter range and a smaller population