User:Abyssal/Prehistory of North America/Selected picture/10

Fossil shells of the scaphitid ammonoids Hoploscaphites (left) and Discoscaphites (right). The shell dates back to the Maastrichtian age (66–72.1 million years ago) of the Late Cretaceous epoch. The Specimen was collected in South Dakota, USA.
Photo credit: H. Zell