Wikipedia

Milk River Formation

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]

Milk River Formation
Stratigraphic range:
Santonian-Campanian
~84.1–83.6 Ma
↓
Outcrops along the Milk River
TypeGeological formation
Unit ofMontana Group
Sub-unitsDeadhorse Coulee Member
Virgelle Member
Telegraph Creek Member
UnderliesPakowki Formation
OverliesColorado Group
Thicknessup to 113 metres (370 ft)[1]
Lithology
PrimarySandstone
OtherSiltstone, shale, coal
Location
RegionAlberta
Country Canada
Type section
Named forMilk River
Named byD.B. Dowling, 1916[2]

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]

Stratigraphy and lithology edit

 
Sandstones of the Milk River Formation at Writing-on-Stone Provincial Park

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]

  • Telegraph Creek Member, at the base, consists primarily of mudstones and shales deposited in offshore marine settings. It has produced the ammonite index fossil Desmoscaphites bassleri, which indicates an age of ~84. Ma.[5][3]
  • Virgelle Member, the central member, is a sequence of massive, cliff-forming, yellow to white sandstones that were deposited in shoreface and tidal channel environments. It can be seen at Writing-on-Stone Provincial Park.[5]
  • Deadhorse Coulee Member, at the top, consists of predominantly nonmarine shales, siltstones, sandstones, and coal beds that were deposited in rivers, floodplains and swamps.[5] Most of the vertebrate fossils have come from this member.[5]

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

 
Belonostomus
 
Lepisosteus

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

 
Albanerpeton

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

N. lithographicus

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

Lithostrotia[6]

Indeterminate

Caudal Centrum

An indeterminate Titanosaurian sauropod, the first from Canada. Cited to be similar to caudals referred to Alamosaurus.[6]

Acrotholus[7]

A. audeti

Skull domes

A pachycephalosaur

 
Acrotholus
 
Saurornitholestes

Brachyceratops[8]

Indeterminate[8]

Continuoolithus[9] cf. C. canadensis One eggshell fragment Laid by a theropod.

Gryphoceratops[10]

G. morrisoni

Partial right dentary

A leptoceratopsid

Kritosaurus[11]

Indeterminate

Palaeoscincus[12]

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

Saurornitholestes[14]

S. langstoni[14]

Dromaeosauridae

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.

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

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 Images

Albertatherium

A. primus

Peradectidae

 
Alphadon
 
Didelphodon

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. ^ Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. ISBN 0-920230-23-7.
  2. ^ Dowling, D.B., 1916. Water Supply, Southeastern Alberta (Contains Geological Map 1604); Geological Survey of Canada, Summary Report 1915, pp. 102-110.
  3. ^ a b Fowler, Denver Warwick (2017-11-22). "Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America". PLOS ONE. 12 (11): e0188426. doi:10.1371/journal.pone.0188426. ISSN 1932-6203. PMC 5699823. PMID 29166406.
  4. ^ a b Payenberg, T.D.H., Braman, D.R. and Miall, A.D. 2003. Depositional environments and stratigraphic architecture of the Late Cretaceous and Eagle formations, southern Alberta and north-central Montana: Relationships to shallow gas. Bulletin of Canadian Petroleum Geology, vol. 51, no. 2, p. 155-176.
  5. ^ a b c d e f Payenberg, T.D.H., 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 the Eagle Formation in Montana utilising stratigraphy, U-Pb geochronology, and palynology, Canadian Journal of Earth Sciences, vol. 39, p. 1553-1577.
  6. ^ a b Evans, D. C.; Ryan, M. J. (2018). "The first occurrence of a sauropod body fossil in Canada, with implications for the "sauropod hiatus" in North America". Journal of Vertebrate Paleontology. 1: 207.
  7. ^ 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. Bibcode:2013NatCo...4.1828E. doi:10.1038/ncomms2749. PMID 23652016.
  8. ^ a b Listed as "cf. Brachyceratops sp." in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  9. ^ a b c d e Zelenitsky, Darla K.; Therrien, François; Tanaka, Kohei; Kobatashi, Yoshitsugu; DebBuhr, Christopher L. (2017). "Dinosaur eggshells from the Santonian Milk River Formation of Alberta, Canada". Cretaceous Research. 74: 181–187. doi:10.1016/j.cretres.2017.02.016.
  10. ^ Michael J. Ryan; David C. Evans; Philip J. Currie; Caleb M. Brown; 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.
  11. ^ Listed as "cf. Kritosaurus sp." in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  12. ^ Listed as "cf. Kritosaurus" in "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  13. ^ a b c d "1.4 Alberta, Canada; 5. Milk River Formation," in Weishampel, et al. (2004). Page 576.
  14. ^ 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 https://web.archive.org/web/20090815182206/http://www.museums.ualberta.ca/dig/search/vpaleo/index.html
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