Hoploscaphites gilberti from the Campanian Pierre Shale of Butte County, South Dakota (AMNH 64615). Specimen whitened to highlight aspects of shell morphology. Images used with permission from Landman et al. (2013, fig. 11i-k).Holotype of Hoploscaphites gilberti from the Campanian Pierre Shale of Butte County, South Dakota (AMNH 64559). Specimen whitened to highlight aspects of shell morphology. Images used with permission from Landman et al. (2013, fig. 6s-u).Paratype of Hoploscaphites gilberti from the Campanian Pierre Shale of Butte County, South Dakota (AMNH 64573). Specimen whitened to highlight aspects of shell morphology. Images used with permission from Landman et al. (2013, fig. 11s-v).