The Tongue River Member is the uppermost geologic member of the Fort Union Formation in Montana, North Dakota, Wyoming. The strata are yellow or light-colored massive sandstones and numerous thick coal beds.Thom, W.T., Jr., and Dobbin, C.E., 1924, Stratigraphy of Cretaceous-Eocene transition beds in eastern Montana and the Dakotas: Geological Society of America Bulletin, v. 35, no. 9, p. 481-505.

The vertebrate fossil fauna includes fishes, turtles, crocodiles, and mammals. Mammalian genera known from rocks of both the Torrejonian and the Tiffanian land mammal ages (middle and late Paleocene) are present.

See also

List of fossiliferous stratigraphic units in North Dakota Paleontology in North Dakota Paleontology in Wyoming

References