Willwood Formation (Early Eocene, ca. 55–52 Ma) Wyoming, U.S.A.

Goler Formation (Middle–Late Paleocene, ca. 60–56 Ma) California, U.S.A.

Fort Union Formation (Paleocene, ca. 66–56 Ma) Montana & Wyoming, U.S.A.

Denver Formation, D1 Sequence (Paleocene, ca. 66–65 Ma) Colorado, U.S.A.

Intertrappean Beds (Late Cretaceous–Early Paleocene, ca. 68–65 Ma) Maharashtra, India

Hell Creek Formation (Late Cretaceous, ca. 68–66 Ma) Montana, U.S.A.

Lance Formation (Late Cretaceous, ca. 68–66 Ma) Wyoming, U.S.A.

Meeteetse Formation (Late Cretaceous, ca. 72–68 Ma) Wyoming, U.S.A.

Judith River Formation (Late Cretaceous, ca. 80–75 Ma) Montana, U.S.A.

Mesaverde Formation (Late Cretaceous, ca. 82–74 Ma)

Egg Mountain, Two Medicine Formation (Late Cretaceous, ca. 75.5 Ma) Montana, U.S.A.

Cloverly Formation (Early Cretaceous, ca. 140–100 Ma) Montana & Wyoming, U.S.A.

Morrison Formation (Late Jurassic, ca. 156–146 Ma) Wyoming, U.S.A.

Chinle Formation (Late Triassic, 225–205 Ma) Arizona, U.S.A.

Bighorn Basin, Wyoming Field Mapping (Cambrian–Paleogene rocks) Iowa State University/U. Nebraska-Lincoln Geology Field School