Willow Tank Formation

The Willow Tank Formation in Nevada preserves part of the region’s Cretaceous past in surface outcrops. Once thought to be Early Cretaceous in age, it is now more often placed in the Late Cretaceous Cenomanian, aligning it broadly with the Cloverly and Cedar Mountain formations in the western United States. It was deposited in an anastomosed river system of interconnected channels and floodplains, a setting reflected in fossils of fish, turtles, crocodyliforms, gastropods, coprolites, trace fossils, dinosaurs, and dinosaur eggs. Its dinosaur record includes several fragmentary groups, the ootaxon Macroelongatoolithus carlylei, and Nevadadromeus schmitti, helping document inland river environments and terrestrial life in the Cretaceous American West.

Nevada · United States