| Mississippian
Order Goniatida
Family Anthracoceratidae
Bear Gulch Limstone |
Cambrian
Trilobite Order Ptychopariida
Family Alokistocaridae
Walsey Formation
|
Cretaceous
Subclass Diapsida
Order Crocodilia
Hell Creek Formation |
Mississippian
Order Paleonisciformes
Bear Gulch Limstone |
