Milk River Formation
Encyclopedia
The Milk River Formation is a near- shore to terrestrial sedimentary unit deposited during the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

 (late Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...

 to early Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

) in southern Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

. It is equivalent to the marine Lea Park Formation
Lea Park Formation
The Lea Park Formation is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin, Canada.It takes the name from the settlement of Lea Park, Alberta, located north-west of Lloydminster on the banks of the North Saskatchewan River. It was first defined in an outcrop...

 of eastern Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...

, and the Eagle
Eagle Sandstone
The Eagle Sandstone is a geological formation in Montana whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-References:...

 and Telegraph Creek Formation
Telegraph Creek Formation
The Telegraph Creek Formation is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.-See also:* List of dinosaur-bearing rock formations...

s of north-central Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

, and to the upper part of the Niobrara Formation
Niobrara Formation
The Niobrara Formation, also called the Niobrara Chalk , is a geologic formation in North America that was laid down between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian ages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member...

 in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...

.

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

  • Telegraph Creek – The lowest member, it represents mudstone
    Mudstone
    Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

     deposited just offshore in a marine setting. It has produced the ammonite
    Ammonite
    Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...

     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
    Shalës
    Shalës is a municipality in the Elbasan District, Elbasan County, central Albania. The municipality consists of the villages Shalës, Licaj, Kurtalli, Xibrake, Xherie and Kodras....

    , 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

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

Cartilaginous fishes

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

Remains of Acipenseridae, Amiidae
Amiidae
Amiidae is a family of primitive ray-finned fish. Only one species, Amia calva, the bowfin, survives today, although additional species in all four subfamilies are known from Jurassic, Cretaceous, and Eocene fossils....

, Esocidae, indeterminate genera and species.
Bony fishes reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes Images

Belonostomus
Belonostomus
Belonostomus or Diphyodus is a genus of prehistoric fish that was described by Louis Agassiz in 1844. Fossils range from to Belonostomus (meaning "big long mouth") or Diphyodus (meaning "double tooth") is a genus of prehistoric fish that was described by Louis Agassiz in 1844. Fossils range...


Indeterminate

Aspidorhynchidae


Lepisosteus
Lepisosteus
Lepisosteus is a genus of gars in the family Lepisosteidae.There are four species:* Lepisosteus oculatus Winchell, 1864 * Lepisosteus osseus...


L. occidentalis

Lepisosteidae

Palaeolabrus

Indeterminate

Lepisosteidae

Amphibians

Amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

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

Albanerpeton
Albanerpeton
Albanerpeton is an extinct genus of salamander-like lissamphibian found in North America and Europe. Members of the genus have a robust head and neck which likely allowed them to actively burrow and they lived in a wide range of environments...


A. galaktion

Albanerpetontidae
Albanerpetontidae
Albanerpetontodae is an extinct family of lissamphibians.-External links:*...



A. nexuosus

Albanerpetontidae
Albanerpetontidae
Albanerpetontodae is an extinct family of lissamphibians.-External links:*...


Opisthotriton
Opisthotriton
Opisthotriton is an extinct genus of prehistoric salamanders that lived in North America between at least the Upper Cretaceous and the Paleocene....


Indeterminate

Batrachosauroididae

Squamates

Indeterminate Anguidae
Anguidae
The Anguidae is a large and diverse family of lizards native to the northern hemisphere. The group includes the slowworms, glass lizards, and alligator lizards, among others. Anguidae is divided into three subfamilies and contains 94 species in eight genera. Their closest living relatives are the...

 and Xenosauridae
Xenosauridae
The Xenosauridae is a family of lizards native to Central America and China. Also known as knob-scaled lizards, they have rounded, bumpy scales and osteoderms. Most species prefer moist or semi-aquatic habitats, although they are widespread within their native regions, with some even inhabiting...

 genera and species.
Squamates reported from the Milk River Formation
Genus Species Location Stratigraphic position Material Notes

Aocnodromeus

A. corrugatus

Scincidae

Chamops

Indeterminate

Teiidae
Teiidae
Teiidae is a family of lizards native to the Americas, generally known as whiptails. The group includes the parthenogenic genera Cnemidophorus and Aspidoscelis, and the non-parthenogenic Tupinambis. It has over 230 member species in ten genera...


Coniophis

cf. C. precedens

Aniliidae
Aniliidae
The Aniliidae are a monotypic family created for the monotypic genus Anilius that contains the species A. scytale, found in South America. This snake possesses a vestigial pelvic girdle that is visible as a pair of cloacal spurs. It is ovoviviparous. The diet consists mainly of amphibians and...


Cnephasaurus

C. locustivorus

Iguanidae
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...


Glyptogenys

G. ornata

Teiidae
Teiidae
Teiidae is a family of lizards native to the Americas, generally known as whiptails. The group includes the parthenogenic genera Cnemidophorus and Aspidoscelis, and the non-parthenogenic Tupinambis. It has over 230 member species in ten genera...


Parasaniwa?

Indeterminate

Necrosauridae

Penemabuya

P. antecessor

Scincidae

Sphenosiagon

S. simplex

Teiidae
Teiidae
Teiidae is a family of lizards native to the Americas, generally known as whiptails. The group includes the parthenogenic genera Cnemidophorus and Aspidoscelis, and the non-parthenogenic Tupinambis. It has over 230 member species in ten genera...


Turtles

Indeterminate Solemydidae and Trionychidae
Trionychidae
Trionychidae is a taxonomic family which comprises a number of turtle genera commonly known as softshells. They are also sometimes called pancake turtles. Softshells consist of some of the world's largest fresh water turtles, though many can adapt to living in highly brackish areas. Members of this...

 genera and species.
Turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...

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

Adocus

Indeterminate

Adocidae

Basilemys

Indeterminate

Nanhsiungchelyidae

?Boremys

Indeterminate

Baenidae
Baenidae
Baenidae is an extinct family of cryptodiran turtles.-External links:* http://www.nhm.org/site/sites/default/files/dinosaur_institute/pdf/NHM_DI_proytecto_dino_Erika_Canola_Baenidae_Turtle_experience.pdf...


?Compsemys
Compsemys
Compsemys is a genus of prehistoric turtle from the Late Cretaceous and Paleocene of North America. Although several species have been described, they are all considered synonyms of one species, C. victa, first described by Joseph Leidy in 1856...


Indeterminate

Family indeterminant

Neurankylus

Indeterminate

Baenidae
Baenidae
Baenidae is an extinct family of cryptodiran turtles.-External links:* http://www.nhm.org/site/sites/default/files/dinosaur_institute/pdf/NHM_DI_proytecto_dino_Erika_Canola_Baenidae_Turtle_experience.pdf...


Plesiobaena
Plesiobaena
Plesiobaena is an extinct genus of turtle which existed in the Belly River Formation, Canada during the late Cretaceous period . It was first named by Lambe, L. M. in 1972 and the type species is Plesiobaena antiqua....


Indeterminate

Baenidae
Baenidae
Baenidae is an extinct family of cryptodiran turtles.-External links:* http://www.nhm.org/site/sites/default/files/dinosaur_institute/pdf/NHM_DI_proytecto_dino_Erika_Canola_Baenidae_Turtle_experience.pdf...


Crocodilians

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

Gilchristosuchus
Gilchristosuchus
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...


G. palatinus

Dinosaurs

Indeterminate Ankylosauridae
Ankylosauridae
An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event...

, Aves, Ceratopsidae
Ceratopsidae
Ceratopsidae is a speciose group of marginocephalian dinosaurs including Triceratops and Styracosaurus...

, Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...

, Hadrosauridae, Nodosauridae
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...

, Ornithomimidae, Pachycephalosauridae, Protoceratopsid
Protoceratopsid
A protoceratopsid is a dinosaur of the family Protoceratopsidae. The name 'protoceratopsid' is derived from Greek for 'first horned face'. They resembled and were closely related to, ceratopsids but were generally smaller and more primitive...

ae, Thescelosauridae, and Tyrannosauridae
Tyrannosauridae
Tyrannosauridae is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The exact number of genera is controversial, with some experts recognizing as few as three...

 genera and species.
Dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

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

Brachyceratops
Brachyceratops
Brachyceratops is a dubious genus of ceratopsian dinosaur known only from partial juvenile specimens dating to the late Cretaceous Period of Montana, United States....


Indeterminate


Kritosaurus
Kritosaurus
Kritosaurus is an incompletely known but historically important genus of hadrosaurid dinosaur. It lived about 73 million years ago, in the Late Cretaceous of North America...


Indeterminate

Palaeoscincus
Palaeoscincus
Palaeoscincus is a dubious genus of ankylosaurian dinosaur based on teeth from the mid-late Campanian-age Upper Cretaceous Judith River Formation of Montana...


Indeterminate

cf. Paronychodon
Paronychodon
Paronychodon was a theropod dinosaur genus. It is a tooth taxon, considered dubious because of the fragmentary nature of the fossils, which include "buckets" of teeth but no other remains...


cf. P. lacustris

Theropoda
Theropoda
Theropoda is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants . Dinosaurs belonging to the suborder theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory...

 incertae sedis

cf. Richardoestesia

cf. R. gilmorei

Maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...

 incertae sedis

cf. R. isosceles

Maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...

 incertae sedis

Saurornitholestes
Saurornitholestes
Saurornitholestes is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Alberta, Montana and New Mexico....


S. langstoni

Dromaeosauridae
Dromaeosauridae
Dromaeosauridae is a family of bird-like theropod dinosaurs. They were small- to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek dromeus meaning 'runner' and sauros meaning 'lizard'...


Other mammals

Other Mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

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

Alticonodon

A. lindoei

Triconodontidae
Triconodontidae
Triconodontidae is an extinct family of actively mobile mammal, endemic to what would be North America, Europe, and Africa during the Jurassic through Cretaceous periods from 155.7—70.6 mya, existing for approximately .-Taxonomy:...


Cimexomys
Cimexomys
Cimexomys is an extinct North American mammal that lived from the Upper Cretaceous to the Paleocene. For a while, it shared the world with dinosaurs, but outlived them. It was a member of the extinct order Multituberculata and lies within the suborder Cimolodonta...


C. antiquus

Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....

?

C. magister

Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....

?

Cimolodon
Cimolodon
Cimolodon is a genus of mammal from the Upper Cretaceous of North America. It was a member of the extinct order of Multituberculata within the suborder Cimolodonta and possibly the family Cimolodontidae....


C. electus

Cimolodontidae
Cimolodontidae
Cimolodontidae is a family of fossil mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America. There is some doubt as to whether Cimolodon is within this taxon. If not, the name of the family would still be valid...


C. similis

Cimolodontidae
Cimolodontidae
Cimolodontidae is a family of fossil mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America. There is some doubt as to whether Cimolodon is within this taxon. If not, the name of the family would still be valid...


Cimolomys
Cimolomys
Cimolomys is a mammal genus from the Upper Cretaceous of North America. It was a member of the extinct order Multituberculata within the suborder Cimolodonta and family Cimolomyidae.The genus Cimolomys was named by Othniel Charles Marsh in 1889...


Indeterminate

Cimolomyidae
Cimolomyidae
Cimolomyidae is a family of fossil mammal within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and the Paleocene of North America and perhaps Mongolia. The family is part of the suborder Cimolodonta. Other than that, their systematic relationships are hard...


Ectypodus

cf. E. powelli

Meniscoessus
Meniscoessus
Meniscoessus is a genus of extinct mammal from the Upper Cretaceous Period of what is now North America. It lived toward the end of the "age of the dinosaurs" and was a member of the extinct order Multituberculata. It lies within the suborder Cimolodonta and family Cimolomyidae.The genus...


M. ferox

Cimolomyidae
Cimolomyidae
Cimolomyidae is a family of fossil mammal within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and the Paleocene of North America and perhaps Mongolia. The family is part of the suborder Cimolodonta. Other than that, their systematic relationships are hard...


Mesodma
Mesodma
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America...


Mesodma senecta

Indeterminate

Mesodma
Mesodma
Mesodma is an extinct genus of mammal, a member of the extinct order Multituberculata within the suborder Cimolodonta, family Neoplagiaulacidae. It lived during the upper Cretaceous and Paleocene Periods of what is now North America...


Mesodma senecta

Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....


Indeterminate

Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....


Mictodon

Mictodon simpsoni

Tinodontidae
Tinodontidae
Tinodontidae is an extinct family of actively mobile mammal, endemic to what would now be North America, Asia, Europe, and Africa during the Jurassic and Cretaceous periods.-Taxonomy:Tinodontidae...


Paracimexomys
Paracimexomys
Paracimexomys is a genus of extinct mammals in the also extinct Multituberculata order. Paracimexomys lived during the Cretaceous period. The few fossils remains come from North America. Some Romanian fossils were also tentatively assigned to this genus, though that classification now seems...


P. magister

Family indeterminent

Paranyctoides

Paranyctoides maleficus

Nyctitheriidae

Picopsis

P. pattersoni

Picopsidae

Indeterminate

Picopsidae

Potamotelses

P. aquilensis

Potamotelsidae

Symmetrodontoides

S. canadensis

Spalacotheriidae

Viridomys
Viridomys
Viridomys is a genus of extinct mammal from the Upper Cretaceous of North America. It was a member of the extinct order of Multituberculata, and lived during the Mesozoic, also known as the "age of the dinosaurs." It's within the suborder of Cimolodonta, though its further affinities are...


V. orbatus

Neoplagiaulacidae
Neoplagiaulacidae
Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through the Eocene. Representatives have been found in North America, Europe and Asia....

?

Didelphomorphs

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

Albertatherium

A. primus

Peradectidae

A. secundus

Peradectidae

Alphadon
Alphadon
Alphadon was a genus of small, primitive mammal that was a member of the metatherians, a group of mammals that includes modern-day marsupials. Its fossils were first discovered and named by George Gaylord Simpson in 1929....


A. halleyi

Peradectidae

Indeterminate

Peradectidae

Aquiladelphis

A. incus

Aquiladelphidae

A. minor

Aquiladelphidae

Didelphodon
Didelphodon
Didelphodon is a genus of stagodont marsupials from the Late Cretaceous of North America. Three species are known: Didelphodon vorax, D. padanicus, and D. coyi. Although perhaps little larger than a Virginia Opossum, it was one of the largest mammals of the Mesozoic...


Indeterminate

Stagodontidae

Eodelphis
Eodelphis
Eodelphis meaning "early opossum" is a genus of stagodont marsupials from the Late Cretaceous of North America, with distinctive crushing dentition. Named species include E. browni and the more advanced E. cutleri...


Indeterminate

Stagodontidae

Iqualadelphis

I. lactea

Pediomyidae

Pediomys

cf. P. clemensi

Pediomyidae

P. exiguus

Pediomyidae

P. florencae

Pediomyidae

Protalphadon

P. creber

Peradectidae
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