# List of fossiliferous stratigraphic units in Montana

This article contains a list of fossil-bearing stratigraphic units in the state of Montana, U.S.

## Sites

| Group or Formation | Period |
| Alan Mountain Limestone | Carboniferous |
| Amsden Formation | Carboniferous |
| Arikaree Formation | Neogene |
| Bear Formation | Paleogene |
| Bearpaw Formation | Cretaceous |
| Bearpaw Shale | Cretaceous |
| Benton Shale | Cretaceous |
| Big Snowy Formation | Carboniferous |
| Big Snowy Group/Heath Formation | Carboniferous |
| Blackleaf Formation | Cretaceous |
| Blacktail Deer Creek Formation | Cretaceous |
| Cameron Creek Formation | Carboniferous |
| Castle Reef Dolomite | Carboniferous |
| Claggett Formation | Cretaceous |
| Claggett Shale | Cretaceous |
| Climbing Arrow Formation | Paleogene |
| Cloverly Formation | Cretaceous |
| Cody Shale | Cretaceous |
| Colorado Group/Belle Fourche Formation | Cretaceous |
| Cook Ranch Formation | Paleogene |
| Deadwood Formation | Ordovician, Cambrian |
| Dearborne Limestone | Cambrian |
| Deep River Formation | Neogene |
| Dell Beds Formation | Paleogene |
| Dinwoody Formation | Triassic |
| Dunbar Creek Formation | Paleogene |
| Eagle Formation | Cretaceous |
| Ellis Formation | Jurassic |
| Flaxville Gravels Formation | Neogene |
| Fort Union Formation | Paleogene, Cretaceous |
| Fort Union No. 3 Beds (Melville) Formation | Paleogene |
| Fort Union Group/Tullock Formation | Paleogene |
| Fox Hills Sandstone | Cretaceous |
| Graneros Shale | Cretaceous |
| Greyson Shale | Precambrian |
| Hell Creek Formation | Paleogene, Cretaceous |
| Hepburn's Mesa Formation | Neogene |
| Horsethief Formation | Cretaceous |
| Jefferson Formation | Devonian |
| Judith River Formation | Cretaceous |
| Kishenehn Formation | Paleogene |
| Kootenai Formation | Cretaceous |
| Lance Formation | Cretaceous |
| Lebo Formation | Paleogene |
| Livingston Formation | Paleogene |
| Lodgepole Limestone | Carboniferous |
| Ludlow Formation | Paleogene |
| Madison Group/Lodgepole and Mission Canyon Formation | Mississippian |
| Madison Valley Formation | Neogene |
| Madison Valley Equivalent Formation | Neogene |
| Madison Group/Allan Mountain Limestone | Carboniferous |
| Madison Group/Lodgepole Formation | Carboniferous |
| Madison Group/Lodgepole Limestone | Carboniferous |
| Marias River Shale | Cretaceous |
| Meagher Formation | Cambrian |
| Melville Formation | Paleogene |
| Montana Formation | Cretaceous |
| Montana Group/Eagle Sandstone | Cretaceous |
| Montana Group/Hell Creek Formation | Cretaceous |
| Montana Group/Judith River Formation | Cretaceous |
| Montana Group/Two Medicine Formation | Cretaceous |
| Morrison Formation | Jurassic |
| Mowry Shale | Cretaceous |
| Otter Formation | Carboniferous |
| Pagoda Formation | Cambrian |
| Park City Formation | Permian |
| Passamari Formation | Paleogene |
| Passamari Formation | Paleogene |
| Pentagon Formation | Cambrian |
| Phosphoria Formation | Permian |
| Pierre Shale | Cretaceous |
| Pilgrim Formation | Cambrian |
| Polecat Bench Formation | Paleogene |
| Renova Formation | Paleogene |
| Ruby River Basin Group/Renova Formation | Paleogene |
| Sage Creek Formation | Paleogene |
| Sappington Formation | Carboniferous, Devonian |
| Sawtooth Formation | Jurassic |
| Shedhorn Formation | Permian |
| Shedhorn Sandstone | Permian |
| Shell Creek Shale | Cretaceous |
| Sixmile Creek Formation | Neogene |
| Snowy Range Formation | Cambrian |
| St. Mary River Formation | Cretaceous |
| Telegraph Creek Formation | Cretaceous |
| Thaynes Formation | Triassic |
| Thermopolis Shale | Cretaceous |
| Three Forks Formation | Devonian |
| Three Forks Shale | Devonian |
| Tongue River Formation | Paleogene |
| Toston Formation | Paleogene |
| Tullock Formation | Paleogene |
| Two Medicine Formation | Cretaceous |
| Upper Hell Creek Formation | Cretaceous |
| Virgelle Sandstone | Cretaceous |
| White River Formation | Paleogene |
| Willow Creek Formation | Cretaceous |
| Wiota Gravels | Quaternary |
| Wolsey Formation | Cambrian |
| Wolsey Shale | Cambrian |