Ammonite Fossil from the Hopewell Mound Group: Source and Significance

Among the thousands of artifacts recovered in 1891–1892 from Mound 25 of the Middle Woodland Hopewell Mound Group in Ross County, Ohio, is a Cretaceous scaphitid ammonite fossil. We have identified the ammonite as Hoploscaphites brevis, a well-known and well-studied index fossil used to subdivide the Upper Cretaceous deposits of the western interior of North America into biostratigraphic zones. The North American extent of this species is limited to parts of the Northern Great Plains, with the probable source of the Hopewell Mound Group specimen being the Sage Creek area in Pennington County, South Dakota. This probable source area for the fossil is consistent with that proposed by Charles Willoughby in the late 1800s. Both ethnological information and archaeological data, including from sites contemporaneous with Mound 25, indicate that ammonite fossils were highly prized among the people of the Northern Great Plains for curing the sick and bringing success in hunting, war, and other endeavors. Conversely, both ethnological information and archaeological data from Eastern Woodland cultures indicate ammonite fossils did not have the same allure among Eastern Woodland people. This and other information suggest that the Hopewell Mound Group ammonite fossil was indirectly procured through interaction with people living in the area where it originated.