DetailsHoploscaphties sp. ammonite fossil collected from the Cretaceous Pierre Shale Formation of Dawson County, Montana, USA. Hoploscaphites is an extinct subgenus of Scaphites i.e. a genus of ammonite which became most dominant and widespread during the Late Cretaceous. This specimen measures 6.5 cm in diameter; it has an involute shell, abundant tubercles towards the venter and ribs which have worn and become some what indistinct. Supplied in a small plastic bag with an information label.