Milk River Formation

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Milk River Formation
Stratigraphic range: Upper Cretaceous
Milkriverpan.jpg
Type Geological formation
Unit of Montana Group
Sub-units Telegraph Creek, Virgelle, Deadhorse Coulee Members
Overlies Colorado Group
Thickness up to 112 feet (30 m)[1]
Lithology
Primary Sandstone
Other Shale
Location
Region Alberta, Montana
Country  Canada,  United States
Type section
Named for Milk River
Named by Dowling, D.B., 1916[2]

The Milk River Formation is a near- shore to terrestrial sedimentary unit deposited during the Late Cretaceous (late Santonian to early Campanian) in southern Alberta. It is equivalent to the marine Lea Park Formation of eastern Alberta, and the Eagle and Telegraph Creek Formations of north-central Montana, and to the upper part of the Niobrara Formation in Kansas.

In Alberta, the Milk River Formation is subdivided into the Telegraph Creek, Virgelle, and Deadhorse Coulee Members. The formation has produced an extensive but little known vertebrate fauna (see Table). Radiometric dates place deposition of the Milk River Formation between ~84.5 Ma and 83.5 Ma (Payenberg et al. 2002).

Members[edit]

  • Telegraph Creek – The lowest member, it represents mudstone deposited just offshore in a marine setting. It has produced the ammonite index fossil Desmoscaphites bassleri (Payenberg et al. 2002), which has an age of ~84.5 Ma.
  • Virgelle – Overlying the Telegraph Creek Member, it is a massive cliff-forming yellow to white sandstones. It was deposited in a shoreface environment, including beach, etc. (Payenberg et al. 2002).
  • Deadhorse Coulee – Consists of shales, siltsones, sandstones, and coal beds. The Member was deposited in rivers, floodplains and swamps. Most of the vertebrate fossils come from this member.

There are some dinosaur remains from the Formation, but these are not very well known. A more concerted effort at locating specimens would undoubtedly produce many new taxa.

Vertebrates[edit]

(references: Brinkman 2003; Gao and Fox 1995; Hilton and Grande 2006; Larson 2008; Sullivan 2003; University of Alberta webpage)

Cartilaginous fishes[edit]

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

Lonchidion

Indeterminate

Hybodontoidea

Myledaphus

M. bipartitus

Rhinobatoidei

Bony fishes[edit]

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

Belonostomus

Indeterminate

Aspidorhynchidae

Lepisosteus

L. occidentalis

Lepisosteidae

Palaeolabrus

Indeterminate

Lepisosteidae

Amphibians[edit]

Amphibians reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes Images

Albanerpeton

A. galaktion

Albanerpetontidae

A. nexuosus

Albanerpetontidae

Opisthotriton

Indeterminate

Batrachosauroididae

Squamates[edit]

Indeterminate Anguidae and Xenosauridae genera and species.

Squamates reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Aocnodromeus

A. corrugatus

Scincidae

Chamops

Indeterminate

Teiidae

Coniophis

cf. C. precedens

Aniliidae

Cnephasaurus

C. locustivorus

Iguanidae

Glyptogenys

G. ornata

Teiidae

Parasaniwa?

Indeterminate

Necrosauridae

Penemabuya

P. antecessor

Scincidae

Sphenosiagon

S. simplex

Teiidae

Turtles[edit]

Indeterminate Solemydidae and Trionychidae genera and species.

Turtles reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Adocus

Indeterminate

Adocidae

Basilemys

Indeterminate

Nanhsiungchelyidae

?Boremys

Indeterminate

Baenidae

?Compsemys

Indeterminate

Family indeterminant

Neurankylus

Indeterminate

Baenidae

Plesiobaena

Indeterminate

Baenidae

Crocodilians[edit]

Crocodilians reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Gilchristosuchus

G. palatinus

Dinosaurs[edit]

Indeterminate Ankylosauridae, Aves, Ceratopsidae, Dromaeosauridae, Hadrosauridae, Nodosauridae, Ornithomimidae, Pachycephalosauridae, Protoceratopsidae, Thescelosauridae, and Tyrannosauridae genera and species.

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Dinosaurs reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes Images

Acrotholus[3]

A. audeti

Skull domes

A pachycephalosaur

Brachyceratops[4]

Indeterminate[4]

Gryphoceratops[5]

G. morrisoni

Partial right dentary

A leptoceratopsid

Kritosaurus[6]

Indeterminate

Palaeoscincus[7]

Indeterminate

cf. Paronychodon[8]

cf. P. lacustris[8]

Theropoda incertae sedis

cf. Richardoestesia[8]

cf. R. gilmorei[8]

Maniraptora incertae sedis

cf. R. isosceles

Maniraptora incertae sedis

Saurornitholestes[9]

S. langstoni[9]

Dromaeosauridae

Mammals[edit]

Other mammals[edit]

Other Mammals reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Alticonodon

A. lindoei

Triconodontidae

Cimexomys

C. antiquus

Neoplagiaulacidae?

C. magister

Neoplagiaulacidae?

Cimolodon

C. electus

Cimolodontidae

C. similis

Cimolodontidae

Cimolomys

Indeterminate

Cimolomyidae

Ectypodus

cf. E. powelli

Meniscoessus

M. ferox

Cimolomyidae

Mesodma

Mesodma senecta

Indeterminate

Mesodma

Mesodma senecta

Neoplagiaulacidae

Indeterminate

Neoplagiaulacidae

Mictodon

Mictodon simpsoni

Tinodontidae

Paracimexomys

P. magister

Family indeterminent

Paranyctoides

Paranyctoides maleficus

Nyctitheriidae

Picopsis

P. pattersoni

Picopsidae

Indeterminate

Picopsidae

Potamotelses

P. aquilensis

Potamotelsidae

Symmetrodontoides

S. canadensis

Spalacotheriidae

Viridomys

V. orbatus

Neoplagiaulacidae?

Didelphomorphs[edit]

Didelphomorphs reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Albertatherium

A. primus

Peradectidae

A. secundus

Peradectidae

Alphadon

A. halleyi

Peradectidae

Indeterminate

Peradectidae

Aquiladelphis

A. incus

Aquiladelphidae

A. minor

Aquiladelphidae

Didelphodon

Indeterminate

Stagodontidae

Eodelphis

Indeterminate

Stagodontidae

Iqualadelphis

I. lactea

Pediomyidae

Pediomys

cf. P. clemensi

Pediomyidae

P. exiguus

Pediomyidae

P. florencae

Pediomyidae

Protalphadon

P. creber

Peradectidae

See also[edit]

Footnotes[edit]

  1. ^ Lexicon of Canadian Geological Units. "Milk River Formation". Retrieved 2009-02-06. 
  2. ^ Dowling, D.B., 1916. Water Supply, Southeastern Alberta (Contains Geological Map 1604); Geological Survey of Canada, Summary Report 1915, pp. 102-110.
  3. ^ Evans, D. C.; Schott, R. K.; Larson, D. W.; Brown, C. M.; Ryan, M. J. (2013). "The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs". Nature Communications 4: 1828. doi:10.1038/ncomms2749.  edit
  4. ^ a b Listed as "cf. Brachyceratops sp." in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  5. ^ Michael J. Ryan, David C. Evans, Philip J. Currie, Caleb M. Brown and Don Brinkman (2012). "New leptoceratopsids from the Upper Cretaceous of Alberta, Canada". Cretaceous Research 35: 69–80. doi:10.1016/j.cretres.2011.11.018. 
  6. ^ Listed as "cf. Kritosaurus sp." in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  7. ^ Listed as "cf. Kritosaurus" in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  8. ^ a b c d "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  9. ^ a b Listed as "cf. Saurornitholestes langstoni" in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.

References[edit]

  • Brinkman, D. 2003. A review of nonmarine turtlesfrom the Late Cretaceous of Alberta. Canadian Journal of Earth Sciences 40:557-571.
  • Gao, K., Fox, R.C. 1996. Taxonomy and evolution of late Cretaceous lizards (Reptilia: Squamata) from Western Canada. Bulletin of the Carnegie Museum 33: 1-107.
  • Hilton, E.J. And Grande, L. 2006. Review of the fossil record of sturgeons, family Acipenseridae (Actinopterygii: Acipenseriformes), from North America. Journal of Paleontology 80: 672-683.
  • Larson, D.W. 2008. Diversity and variation of theropod dinosaur teeth from the uppermost Santonian Milk River Formation (Upper Cretaceous), Alberta: a quantitative method supporting identification of the oldest dinosaur tooth assemblage in Canada. Canadian Journal of Earth Sciences 45: 1455-1468.
  • Payenberg, T.H.D., Braman, D.R., Davis, D.W., and Miall, A.D. 2002. Litho- and chronostratigraphic relationships of the Santonian–Campanian Milk River Formation in southern Alberta and Eagle Formation in Montana utilising stratigraphy, U–Pb geochronology, and palynology. Canadian Journal of Earth Sciences 39:1553-1577.
  • Sullivan, R.M. 2003. Revision of the dinosaur Stegoceras Lambe (Ornithischia, Pachycephalosauridae). Journal of Vertebrate Paleontology 23: 181-207.
  • University of Alberta Museum http://www.museums.ualberta.ca/dig/search/vpaleo/index.html