| details |
Middle Cenomanian |
Late Cenomanian |
Iowa |
Ravn,R.L. et al. The palynostratigraphy of the Dakota Formation, (?Late Albian-Cenomanian) in its type area, northwestern Iowa and northeastern Nebraska, USA. |
1995 |
| original |
Cenomanian |
|
Iowa |
Hall,J.W. Megaspores and other fossils in the Dakota Formation, (Cenomanian), of Iowa, USA. |
1963 |
| details |
Cenomanian |
Coniacian |
Wyoming |
Griggs,P.H. Stratigraphy and palynology of the Frontier Formation, Big Horn Basin, Wyoming |
1970 |
| details |
Cenomanian |
|
Arizona |
Agasie,J.M. Late Cretaceous palynomorphs from northeastern Arizona. |
1969 |