| System |
Series |
Stage |
Western Interior US Biozone |
| Cretaceous |
Upper Cretaceous | Maastrichtian |
|
| Campanian (part) |
Scaphites hippocrepis |
||
| Scaphites leei |
|||
| Santonian |
Desmoscaphites bassleri |
||
| Desmoscaphites erdmanni |
|||
| Clioscaphites choteauensis |
|||
| Clioscaphites
vermiformis |
|||
| Clioscaphites saxitonianus |
|||
| Coniacian | Scaphites
depressus |
||
| Scaphites ventricosus |
|||
| Forresteria
alluaudi |
|||
| Forresteria peruana |
|||
| Turonian |
Prionocyclus germari |
||
| Prionocyclus quadratus |
|||
| Prionocyclus
novimexicanus |
|||
| Prionocyclus wyomingensis | |||
| Prionocyclus
macombi |
|||
| Prionocyclus
hyatti |
|||
| Collignoniceras praecox |
|||
| Collignoniceras
woollgari |
|||
| Mammites nodosoides |
|||
| Vascoceras birchbyi |
|||
| Pseudaspidoceras flexuosum |
|||
| Watinoceras devonense |
|||
| Cenomanian (part) |
Nigericeras scotti |
||
| Neocardioceras juddii |
|||
| Burroceras clydense |
|||
| Euomphaloceras
septemseriatum |
|||
| Vascoceras diartianum |
|||
| Dunveganoceras conditum |
|||
| Dunveganoceras albertense |
|||
| Lower Cretaceous |
|||