A | B | C | D | E | F | G | H | CH | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
Fort Union Formation
...| Fort Union Formation | |
|---|---|
| Stratigraphic range: Maastrichtian-Selandian (Lancian-Clarkforkian) ~ | |
 Fossils from the Fort Union Formation | |
| Type | Geological formation |
| Sub-units | Atwell Gulch, China Butte, Ekalaka, Lebo, lower Ludlow, Overland, Rock Bench Quarry, Sentinel Butte, Shotgun, Somber beds, Tongue River, Tullock, upper Ludlow, Polecat Bench Formation |
| Underlies | Wasatch Formation |
| Overlies | Hell Creek Formation, Lance Formation |
| Lithology | |
| Primary | Sandstone, shale |
| Other | Coal |
| Location | |
| Region | Montana, North Dakota Wyoming, Colorado |
| Country |  United States |
| Extent | Powder River Basin |
The Fort Union Formation is a geologic unit containing sandstones, shales, and coal beds in Wyoming, Montana, and parts of adjacent states. In the Powder River Basin, it contains important economic deposits of coal, uranium, and coalbed methane.[1]
Description
The Fort Union is mostly of Paleocene age and represents a time of extensive swamps as well as fluvial and lacustrine conditions. The rocks are more sandy in southwestern Wyoming and more coal-bearing in northeast Wyoming and southeast Montana, reflecting a general change from rivers and lakes in the west to swamps in the east, but all three environments were present at various times in most locations.[2]
Coal in the Fort Union in the Powder River Basin occurs mainly in the Tongue River Member, where as many as 32 coal seams total more than 300 feet in thickness.[1] One such bed, the Wyodak Coal near Gillette, Wyoming, is as much as 110 feet (34 m) thick. Most of the coals in the Fort Union Formation are ranked subbituminous.[3]
Fossil content
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Mammals
Cimolestans
| Cimolestans reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Crustulus | C. fontanus | Northeastern Montana.[4] | Tullock Member.[4] | An isolated upper molar.[4] | A pantodont. | |
Leptictids
| Leptictids reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Prodiacodon | P. crustulum | Garfield & McCone counties, Montana.[5] | Tullock Member.[5] | Fragmentary dentary & isolated teeth.[5] | A leptictid. | |
Marsupials
| Marsupials reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Peradectes | P. sp. | Swain Quarry, Wyoming.[6] | Upper & lower molars.[6] | Reassigned to Swaindelphys. | ||
| Swaindelphys | S. cifellii | Swain Quarry, Wyoming.[6] | Upper & lower molars.[6] | An opossum. | ||
Primatomorphs
| Primatomorphs reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Carpodaptes | C. sp. | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | 2 isolated fourth lower premolars.[7] | A carpolestid. |  |
| Chiromyoides | C. caesor | Hell's Half Acre (UCM locality 78009), Mesa County, Colorado.[8] | A single upper incisor (UCM 53515).[8] | A plesiadapid. | ||
| C. gigas | Piceance Creek Basin, Colorado.[8] | Multiple teeth.[8] | A plesiadapid. | |||
| C. sp. | UCM locality 78060, Colorado.[8] | A left molar (UCM 41606).[8] | A plesiadapid. | |||
| Elphidotarsius | E. shotgunensis | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | Right ramus of mandible & isolated teeth.[7] | A carpolestid. | |
| Nannodectes | N. gazini | Fremont County, Colorado.[8] | A right maxilla (USGS 16872).[8] | A plesiadapid. | ||
| Palaechthon | P., near P. alticuspis | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | 3 upper molars & 4 lower molars.[7] | A plesiadapiform. | |
| P. woodi | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | A lower jaw & 13 isolated teeth.[7] | A plesiadapiform. | ||
| Palenochtha | P. cf. minor | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | 5 lower teeth.[7] | A plesiadapiform. | |
| Paromomys | P., near P. depressidens | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | Approximately 12 upper teeth, 8 isolated lower teeth & a jaw fragment.[7] | A paromomyid. | |
| Phenacolemur | P. fremontensis | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | A lower jaw & isolated teeth.[7] | A paromomyid. | |
| P. cf. frugivorus | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | 2 upper molars & 8 isolated lower molars.[7] | A paromomyid. | ||
| Plesiadapis | P. dubius | Piceance Creek Basin, Colorado.[8] | Jaw elements & teeth.[8] | A plesiadapid. |  | |
| P. fodinatus | Piceance Creek Basin, Colorado.[8] | Jaw elements & teeth.[8] | A plesiadapid. | |||
| P. sp. | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | 5 lower molars, 3 anterior upper molars & a premolar.[7] | A plesiadapid. |  | |
| Plesiolestes | P. cf. problematicus | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | Approximately 45 isolated teeth.[7] | A plesiadapiform. | |
| Pronothodectes | P. intermedius | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | Jaw elements & teeth.[7] | A plesiadapid. | |
| Purgatorius | P. janisae | 'Harley's Point’ UCMP locality V77087, Garfield County, Montana.[9] | Tullock Member.[9] | UCMP 150018 (right m1), and UCMP 192398 (left m3).[9] | A purgatoriid. | |
| P. mckeeveri | Garfield County, Montana.[9] | Tullock Member.[9] | Dentary remains & teeth.[9] | A purgatoriid. | ||
| P. cf. P. mckeeveri | Harley's Point’ UCMP locality V77087, Garfield County, Montana.[9] | Tullock Member.[9] | UCMP 150019 (right M2), and UCMP 150020 (right M2).[9] | A purgatoriid. | ||
| Torrejonia | Cf. T. wilsoni | Wind River Basin, Wyoming.[7] | Shotgun Member.[7] | About 14 lower teeth & possibly 3 upper molars.[7] | A plesiadapiform. | |
| Zanycteris | Z. honeyi | UMC locality number 92177, Colorado.[10] | Atwell Gulch Member.[10] | Right maxilla (UCM 87378).[10] | A plesiadapiform. | |
Ungulates
| Ungulates reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Dissacus | D. argenteus | Princeton Quarry, Park County, Wyoming.[11] | Upper part of the formation.[11] | Jaw elements & teeth.[11] | A mesonychid. | |
| D. cf. navajovius | Princeton Quarry, Park County, Wyoming.[11] | Upper part of the formation.[11] | Jaw elements & teeth.[11] | Specimens reassigned to D. argenteus. | ||
| D. praenuntius | Park County, Wyoming.[11] | Upper part of the formation.[11] | Mandible (YPM-PU 16159).[11] | A mesonychid also known from the Willwood Formation. | ||
| Ectocion | E. mediotuber | Princeton Quarry, Wyoming.[12] | Dentary.[12] | A phenacodontid. | ||
| Periptychus | P. carinidens | Makoshika State Park, Montana.[13] | A periptychid also found in the Nacimiento, North Horn, Black Peaks & Animas formations. |  | ||
| Sigynorum | S. magnadivisus | Great Divide Basin, southern Wyoming.[14] | China Butte Member.[14] | An arctocyonid. | ||
Reptiles
Birds
A partial ornithurine coracoid bone found in this formation is identical to others found in the older Hell Creek Formation. At present, this unnamed species is the only known individual bird species that have survived the Cretaceous–Paleogene extinction event.[15]
| Birds reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Locality | Stratigraphic member | Material | Notes | Images |
| Lithornis | L. celetius | Bangtail Quarry, Sedan Quadrangle, Park County, Montana.[16] | A lithornithid. |  | ||
Crocodilians
| Crocodilians reported from the Fort Union Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic member | Material | Notes | Images |
| Allognathosuchus | A. sp. | Princeton Quarry, Park County, Wyoming.[17] | Anterior end of left dentary (PU 16988).[17] | A crocodilian. |  | |