Face and counterface of ammonite Hoploscaphites nebrascensis, USA (South Dakota, Fox Hill Formation), Upper Cretaceous, Maastrichtian (65.5 to 70.6 million years), diam. 13 cm (ammonite)
Face and counterface of ammonite Hoploscaphites nebrascensis, USA (South Dakota, Fox Hill Formation), Upper Cretaceous, Maastrichtian (65.5 to 70.6 million years), diam. 13 cm (ammonite)