The Willow Tank Formation is a geologic formation which outcrops in the U.S. state of Nevada. Initially believed to be of Early Cretaceous (Albian) age, later studies have concluded that it was more likely to be of Late Cretaceous (Cenomanian) age, making it equivalent to the Cloverly and Cedar Mountain Formations. It was deposited in an anastomosed fluvial system.
All paleofauna listed are taken from a list compiled by Bonde (2008a) unless stated otherwise.