| original |
Cenomanian |
|
Iowa |
Ravn,R.L. Montiapollis, n.gen., possible Portulaceae pollen from the Cenomanian of Iowa. |
1987 |
| details |
Cenomanian |
|
Iowa |
Ravn,R.L. et al. The Mid-Cretacous boundary in the western interior seaway, central United States: Implications of palynostratigraphy from the type Dakota Formation. (In: Perspectives on the eastern Margin of the Cretaceous Western Interior Basin. G.W. Shurr et al, editors) |
1994 |
| 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 |