Milk River Formation | |
---|---|
Stratigraphic range: Santonian-Campanian ~ | |
Type | Geological formation |
Unit of | Montana Group |
Sub-units | Deadhorse Coulee Member Virgelle Member Telegraph Creek Member |
Underlies | Pakowki Formation |
Overlies | Colorado Group |
Thickness | up to 113 metres (370 ft) [1] |
Lithology | |
Primary | Sandstone |
Other | Siltstone, shale, coal |
Location | |
Region | Alberta |
Country | Canada |
Type section | |
Named for | Milk River |
Named by | D.B. Dowling, 1916 [2] |
The Milk River Formation is a sandstone-dominated stratigraphic unit of the Western Canada Sedimentary Basin in southern Alberta, Canada. It was deposited in near-shore to coastal environments during Late Cretaceous (late Santonian to early Campanian) time. Based on uranium-lead dating, palynology and stratigraphic relationships, deposition occurred between ~84.1 and 83.6 Ma. [3]
The sandstones of the Virgelle Member in the centre of the formation are well-exposed at Writing-on-Stone Provincial Park in southwestern Alberta, where they bear petroglyphs carved into them by First Nations people.
The formation is fossiliferous and has yielded an extensive vertebrate fauna (see Tables below), as well as fossil ammonites. In some areas it hosts shallow natural gas reservoirs. [4]
The Milk River Formation is an eastward-thinning wedge of clastic sediments that was deposited along the western margin of the Western Interior Seaway during Late Cretaceous (late Santonian to early Campanian) time. It is age-equivalent to the marine shales of the Lea Park Formation in southeastern Alberta, and to the Eagle and Telegraph Creek Formations of north-central Montana. [5] [4]
In Alberta it is subdivided into the following three members: [5]
(references: Brinkman 2003; Gao and Fox 1995; Hilton and Grande 2006; Larson 2008; Sullivan 2003; University of Alberta webpage)
Remains of an indeterminate lamnid genus and species are present.
Cartilaginous fishes reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | |
Indeterminate | ||||||
M. bipartitus | ||||||
Remains of Acipenseridae, Amiidae, Esocidae, indeterminate genera and species.
Bony fishes reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Indeterminate | ||||||
L. occidentalis | ||||||
Indeterminate | ||||||
Amphibians reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
A. galaktion | ||||||
A. nexuosus | ||||||
Indeterminate | ||||||
Indeterminate Anguidae and Xenosauridae genera and species.
Squamates reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | |
A. corrugatus | ||||||
Indeterminate | ||||||
cf. C. precedens | ||||||
C. locustivorus | ||||||
G. ornata | ||||||
Indeterminate | ||||||
P. antecessor | ||||||
S. simplex | ||||||
Indeterminate Solemydidae and Trionychidae genera and species.
Turtles reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | |
Indeterminate | ||||||
Indeterminate | ||||||
? Boremys | Indeterminate | |||||
Indeterminate | Family indeterminant | |||||
N. lithographicus | ||||||
Indeterminate | ||||||
Crocodilians reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | |
G. palatinus | ||||||
Indeterminate Ankylosauridae, Aves, Ceratopsidae, Dromaeosauridae, Hadrosauridae, Nodosauridae, Ornithomimidae, Pachycephalosauridae, Protoceratopsidae, Thescelosauridae, and Tyrannosauridae genera and species.
Color key
| Notes Uncertain or tentative taxa are in small text; |
Dinosaurs reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Indeterminate | Caudal Centrum | An indeterminate Titanosaurian sauropod, the first from Canada. Cited to be similar to caudals referred to Alamosaurus . [6] | ||||
A. audeti | Skull domes | |||||
Indeterminate [8] | ||||||
Continuoolithus [9] | cf. C. canadensis | One eggshell fragment | Laid by a theropod. | |||
G. morrisoni | Partial right dentary | |||||
Indeterminate | ||||||
Indeterminate | ||||||
cf. Paronychodon [13] | cf. P. lacustris [13] | Theropoda incertae sedis | ||||
Porituberoolithus [9] | cf. P. warnerensis | One eggshell fragment | Laid by a theropod | |||
Prismatoolithus [9] | Indeterminate | 6 isolated eggshell fragments | Laid by a theropod. | |||
cf. Richardoestesia [13] | cf. R. gilmorei [13] | Maniraptora incertae sedis | ||||
cf. R. isosceles | Maniraptora incertae sedis | |||||
S. langstoni [14] | ||||||
Spheroolithus [9] | cf. S. choteauensis | 313 isolated eggshell fragments | Laid by an ornithopod. | |||
Triprismatoolithus [9] | Indeterminate | 60 isolated eggshell fragments | Laid by a bird or theropod. | |||
Other Mammals reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | |
A. lindoei | ||||||
C. antiquus | ||||||
C. magister | ||||||
C. electus | ||||||
C. similis | ||||||
Indeterminate | ||||||
cf. E. powelli | ||||||
M. ferox | ||||||
Mesodma senecta | ||||||
Indeterminate | ||||||
P. magister | Family indeterminent | |||||
Paranyctoides maleficus | ||||||
P. pattersoni | ||||||
Indeterminate | ||||||
P. aquilensis | ||||||
S. canadensis | ||||||
V. orbatus | ||||||
Didelphomorphs reported from the Milk River Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
A. primus | ||||||
A. secundus | ||||||
A. halleyi | ||||||
Indeterminate | ||||||
A. incus | ||||||
A. minor | ||||||
Indeterminate | ||||||
Indeterminate | ||||||
I. lactea | ||||||
cf. P. clemensi | ||||||
P. exiguus | ||||||
P. florencae | ||||||
P. creber | ||||||
Montanoceratops is an extinct genus of small ceratopsian dinosaur that lived approximately 70 million years ago during the latter part of the Cretaceous Period in what is now Montana and Alberta. Montanoceratops was a small sized, moderately-built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 2.5 m (8.2 ft) in length and 170 kg (370 lb) in body mass.
Zapsalis is a genus of dromaeosaurine theropod dinosaurs. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include teeth but no other remains.
The Dinosaur Park Formation is the uppermost member of the Belly River Group, a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 76.5 and 74.4 million years ago. It was deposited in alluvial and coastal plain environments, and it is bounded by the nonmarine Oldman Formation below it and the marine Bearpaw Formation above it.
The Oldman Formation is a stratigraphic unit of Late Cretaceous age that underlies much of southern Alberta, Canada. It consists primarily of sandstones that were deposited in fluvial channel and floodplain environments. It was named for exposures along the Oldman River between its confluence with the St. Mary River and the city of Lethbridge, and it is known primarily for its dinosaur remains and other fossils.
The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between 83.5 ± 0.7 Ma and 70.6 ± 3.4 Ma, during Campanian time. It crops out to the east of the Rocky Mountain Overthrust Belt, and the western portion of this formation is folded and faulted while the eastern part, which thins out into the Sweetgrass Arch, is mostly undeformed plains. Below the formation are the nearshore deposits of the Virgelle Sandstone, and above it is the marine Bearpaw Shale. Throughout the Campanian, the Two Medicine Formation was deposited between the western shoreline of the Late Cretaceous Interior Seaway and the eastward advancing margin of the Cordilleran Overthrust Belt. The Two Medicine Formation is mostly sandstone, deposited by rivers and deltas.
The Kirtland Formation is a sedimentary geological formation.
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It was laid down during the same time period as portions of the Two Medicine Formation of Montana and the Oldman Formation of Alberta. It is an historically important formation, explored by early American paleontologists such as Edward Drinker Cope, who named several dinosaurs from scrappy remains found here on his 1876 expedition. Modern work has found nearly complete skeletons of the hadrosaurid Brachylophosaurus.
The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944.
The Bearpaw Formation, also called the Bearpaw Shale, is a geologic formation of Late Cretaceous (Campanian) age. It outcrops in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, and was named for the Bear Paw Mountains in Montana. It includes a wide range of marine fossils, as well as the remains of a few dinosaurs. It is known for its fossil ammonites, some of which are mined in Alberta to produce the organic gemstone ammolite.
The Kaiparowits Formation is a sedimentary rock formation found in the Kaiparowits Plateau in Grand Staircase–Escalante National Monument, in the southern part of Utah in the western United States. It is over 2800 feet thick, and is Campanian in age. This Upper Cretaceous formation was formed from alluvial floodplains of large rivers in coastal southern Laramidia; sandstone beds are the deposit of rivers, and mudstone beds represent floodplain deposits. It is fossiliferous, with most specimens from the lower half of the formation, but exploration is only comparatively recent, with most work being done since 1982. It has been estimated that less than 10% of the Kaiparowits formation has been explored for fossils. Most fieldwork has been conducted by The Natural History Museum of Utah.
The Kanguk Formation is a geological formation in the Northwest Territories and Nunavut, Canada whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.
The Foremost Formation is a stratigraphic unit of Late Cretaceous (Campanian) age that underlies much of southern Alberta, Canada. It was named for outcrops in Chin Coulee near the town of Foremost and is known primarily for its dinosaur remains and other fossils.
The Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and northeastern British Columbia, Canada. Its deposition spanned the time interval from the lower Campanian through to the upper Maastrichtian, between approximately 80 and 68 Ma. It was named by G.M. Dawson in 1881, presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.
The St. Mary River Formation is a geologic formation of Late Cretaceous age of the Western Canada Sedimentary Basin in southwestern Alberta and northwesternmost Montana. It was first described from outcrops along the St. Mary River by George Mercer Dawson in 1883, and it takes its name from the river.
The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. Fossil palms have also been unearthed here.
The Mooreville Chalk is a geological formation in North America, within the U.S. states of Alabama and Mississippi, which were part of the subcontinent of Appalachia. The strata date back to the early Santonian to the early Campanian stage of the Late Cretaceous. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment. It is a unit of the Selma Group and consists of the upper Arcola Limestone Member and an unnamed lower member. Dinosaur, mosasaur, and primitive bird remains are among the fossils that have been recovered from the Mooreville Chalk Formation.
The Demopolis Chalk is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment during the middle Campanian stage of the Late Cretaceous. It is a unit of the Selma Group and consists of the upper Bluffport Marl Member and a lower unnamed member. Dinosaur and mosasaur remains are among the fossils that have been recovered from the Demopolis Chalk.
The Cerro del Pueblo Formation is a geological formation in Coahuila, Mexico whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. The formation is believed to correlate with the Baculites reesidesi and Baculites jenseni ammonite zones, which dates it to 73.63-72.74 Ma.
Gilchristosuchus is an extinct genus of neosuchian crocodyliform. Its fossils have been found in the upper Milk River Formation of Alberta, Canada, in rocks of either latest Santonian or earliest Campanian age. Gilchristosuchus was described in 1993 by Wu and Brinkman. The type species is G. palatinus, in reference to its distinctive palatine bones.