Hell Creek Formation

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Hell Creek Formation
Stratigraphic range: MaastrichtianDanian, 66.8–66 Ma
Hell Creek.jpg
Exposure in the badlands in the vicinity of Fort Peck Reservoir
Type Geological formation
Underlies Fort Union Formation
Overlies Fox Hills Formation
Location
Region  Montana  North Dakota  South Dakota
Country  USA

The Hell Creek Formation is an intensively-studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation includes portions of Montana, North Dakota, South Dakota, and Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation. "Pompey's Pillar" at the Pompeys Pillar National Monument is a small isolated section of the Hell Creek Formation.

It is a series of fresh and brackish-water clays, mudstones, and sandstones deposited during the Maastrichtian and Danian (respectively the end of the Cretaceous period and the beginning of the Paleogene) by fluvial activity in fluctuating river channels and deltas and very occasional peaty swamp deposits along the low-lying eastern continental margin fronting the late Cretaceous Western Interior Seaway. The climate was mild, and the presence of crocodilians suggests a sub-tropical climate, with no prolonged annual cold. The famous iridium-enriched Cretaceous–Paleogene boundary, which separates the Cretaceous from the Cenozoic, occurs as a discontinuous but distinct thin marker bedding above and occasionally within the formation, near its boundary with the overlying Fort Union Formation.

The world's largest collection of Hell Creek fossils is housed and exhibited at the Museum of the Rockies, in Bozeman, Montana. The specimens displayed are the result of the museum's Hell Creek Project, a joint effort between the museum, Montana State University, the University of California, Berkeley, the University of North Dakota and the University of North Carolina which began in 1998.

Geology[edit]

Map of the Hell Creek and Lance formations in western North America

The Hell Creek Formation in Montana overlies the Fox Hills Formation and underlies the Fort Union Formation, and the boundary with the latter occurs near the Cretaceous-Paleogene boundary, which defines the end of the Cretaceous period and has been dated to 66 ± 0.07 Ma old.[1] Fauna characteristic of the Hell Creek (Lancian land vertebrate age) are found as high as a few meters below the boundary.[2]

The K-Pg boundary is generally situated near the contact between the upper Hell Creek and the lower Ludlow member of the Fort Union Formation, though in some areas (e.g. in North Dakota) the boundary is well within the Ludlow Member, 3 meters above the boundary with the Hell Creek in some areas.[2] On the other hand, in some small regions of Montana, the Hell Creek Formation contains the K-Pg boundary, and extends slightly into the Paleogene.[3]

Paleobiota[edit]

The formation has produced impressive assemblages of invertebrates, plants, mammals, fish, reptiles (including the lizard Obamadon), Marine reptile, and amphibians. Notable dinosaur finds include Tyrannosaurus and Triceratops. The most complete Hadrosaurid dinosaur ever found was retrieved in 2000 from the Hell Creek Formation and widely publicised in a National Geographic documentary aired in December 2007. A few bird, mammal, and pterosaur fossils have also been found. Teeth of sharks and rays are sometimes found in the riverine Hell Creek Formation, suggesting that some of these taxa were then, as now, tolerant of fresh water. The "Lancian" fauna is overall more similar (Phylogenetically.) to East Asian and Canadian/Alaskan faunas then most Campanian N. American fauna's.

Amphibians[edit]

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.
Amphibians reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images
Barbourula[4]

Indeterminate[5]

A living Barbourula.

Eopelobates[7]

Indeterminate[5]

Habrosaurus[5]

H. dilatus[5]

Lisserpeton[5]

L. bairdi[5]

Opisthotriton[5]

O. kayi[5]

Paranecturus[8]

P. garbanii[8]

A member of Proteidae.[8]

Proamphiuma[5]

P. cretacica[5]

Prodesmodon[5]

P. copei[5]

Scapherpeton[5]

S. tectum[5]

Scotiophryne[5]

S. pustulosa[5]

Fishes[edit]

Bony fishes[edit]

Bony fishes reported from the Hell Creek Formation
Genus Species Location Stratigraphic position Material Notes Images

Acipenser[9]

A. eruciferus[9]

A sturgeon

A Belonostomus fossil
A living Lepisosteus

Amia[9]

A. fragosa[9]

small amiid fish (ubiquitous). Closely related to the modern Bowfin

Belonostomus[9]

B. longirostris[9]

A long-snouted slender fish (affinity= ?Aspidorhynchidae). Rare

Coriops[11]

C. amnicolus[11]

Lepisosteus[9]

L. occidentalis[9]

garfish ("gar pike") (extremely common)

Palaeolabrus[9]

P. montanensis[9]

Paleopsephurus[9]

P. wilsoni[9]

A paddlefish

Paralbula[13]

P. casei[13]

Platacodon[11]

P. nanus[11]

small teleost fish

Protamia[9]

Indeterminate[9]

Protoscaphirhynchus[9]

P. squamosus[9]

a sturgeon

Cartilaginous fishes[edit]

Cartilaginous fishes reported from the Hell Creek Formation
Genus Species Location Stratigraphic position Material Notes

Ischyrhiza[14]

I. avonicola[14]

Lonchidion[14]

L. selachos[14]

Myledaphus[16]

M. pustulosus[16]

A member of Rajiformes related to guitarfishes.[16] Described on the basis of teeth formerly assigned to the species M. bipartitus.[16]

Restesia[16]

R. americana[16]

A wobbegong.[16]

Marine reptiles[edit]

Marine reptile reported from the Hell Creek Formation
Genus Species Location Stratigraphic position Material Notes

Mosasaurus[16]

M. hoffmannii[16]

A Mosasaur.[16]

Dinosaurs[edit]

Ornithischians[edit]

Ankylosaurs[edit]

Ankylosaurs reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Ankylosaurus[17]

Ankylosaurus magniventris[17]

An ankylosaur. Also found in the Lance and Scollard Formations.

Edmontonia[17]

indeterminate[17]

A nodosaur.

Ceratopsians[edit]

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.
Ceratopsians reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Leptoceratops[17]

Indeterminate[20]

A small primitive-looking ceratopsian.


Tatankaceratops

T. sacrisonorum

  • South Dakota

A ceratopsian possibly synonymous with Triceratops[21]

Torosaurus[17]

T. latus[17]

A ceratopsian possibly synonymous with Triceratops.[22] Also found in the Frenchman and Lance Formations.

Triceratops[17]

T. horridus[17]

  1. Very common.

A ceratopsian, very common. Also found in the Evanston, Frenchman, Kirtland, Lance, Laramie, and Scollard Formations.

T. maximus[17]

"[Eight] vertebrae, [two] ribs."[23]

Later found to be indeterminate ceratopsid remains.[17]

T. prorsus[17]

Very common.[citation needed]

Also found in the Frenchman and Lance Formations.

T. serratus[17]

Later referred to T. horridus.[17]

Ornithopods[edit]

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.
Ornithopods reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Anatosaurus

A. annectens

Reclassified as Edmontosaurus annectens, thought occasionally considered a separate genus.[24]

Anatotitan

A. copei

Junior synonym of Edmontosaurus annectens.[24]

Bugenasaura

B. garbanii

Junior synonym of Thescelosaurus garbanii

B. infernalis

Reclassified as Thescelosaurus

Edmontosaurus

E. annectens

Very common.

A hadrosaur. Also found in the Denver, Frenchman, Lance, Laramie, and Scollard Formations.

Parasaurolophus[25]

P. walkeri[25]

A lambeosaurine hadrosaur that may have lived in the Hell Creek Formation however lack of more evidence makes this unclear.

Thescelosaurus[19]

T. garbanii[26]

T. infernalis

Nomen dubium

T. neglectus[19]

A small ornithopod. Also found in the Frenchman, Lance, Laramie, and Scollard Formations.[28]

Indeterminate[29]

Pachycephalosaurs[edit]

An undescribed Pachycephalosaur is present in North Dakota.[18]

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.
Pachycephalosaurs reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Dracorex[30]

D. hogwartsia[30]

A pachycephalosaur, possibly synonymous with Pachycephalosaurus.

Pachycephalosaurus[17]

P. wyomingensis[17]

A pachycephalosaur. Also found in the Lance Formation.

Sphaerotholus[17]

S. buchholtzae[17]

"Skull material."[31]

A pachycephalosaur, possibly synonymous with Prenocephale.

Stygimoloch[17]

S. spinifer[17]

A pachycephalosaur, possibly synonymous with Pachycephalosaurus. Also found in the Lance Formation.

Indeterminate[19]

Theropods[edit]

Theropod tracks have been found in South Dakota.[19] An unnamed alvarezsaurid is known from Montana.[32]

Tyrannosaurids[edit]

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.
Tyrannosaurids reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Albertosaurus

A. megagracilis"[17]

Remains later referred to Tyrannosaurus rex.[17]

Aublysodon[17]

A. cf. mirandus[17]

Now considered indeterminate tyrannosauroid remains.[17]

A. molnari[17]

Remains later referred to Tyrannosaurus rex.[17]

Dinotyrannus

D. megagracilis

  • Montana

Remains later referred to Tyrannosaurus rex.

Gorgosaurus

G. lancensis

  • Montana

Remains later referred to Nanotyrannus lancensis.

Nanotyrannus[17]

N. lancensis[17]

"Nearly complete skull."[33]

A small tyrannosaur, possibly synonymous with Tyrannosaurus.

Tyrannosaurus[17]

T. rex[17]

A tyrannosaur, known from several specimens including a juvenile nicknamed "Jane". Also found in the Denver, Frenchman, Hill Creek South, Javelina, Kirtland, Lance, McRae, North Horn, Scollard, and Willow Creek Formations.

Ornithomimosaurs[edit]

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.
Ornithomimids reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

"Orcomimus"

unnamed

An ornithomimid. Numem nudum

Ornithomimus[17]

O. velox[17]

An ornithomimid. Hell Creek remains actually intermediate ornthimimids.

Struthiomimus[19]

S. sedens[36]

A large ornithomimid.[36]

Indeterminate[19]

Oviraptorosaurs[edit]

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.
Oviraptorosaurs reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Anzu[17][38]

A. wyliei

  • North Dakota
  • South Dakota
Reconstructed Anzu skull, CMNH

Leptorhynchos (dinosaur)[38]

L. elegans

  • Montana

Alternately classified as a species of Leptorhynchos, L. elegans is originally known from the Campanian Dinosaur Park Formation. A partial caenagnathid foot, specimen MOR 752, from the Hell Creek Formation has sometimes been referred to E. elegans.

Eumaniraptorans[edit]

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.
Eumaniraptorans reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Avisaurus[17]

A. archibaldi[17]

Two adult and one juvenile specimens, all based on lower leg elements.[citation needed]

An enantiornithine.

Acheroraptor[39]

A. temertyorum [39]

  • Montana[39]
  • North Dakota?
  • South Dakota?

Partial skull (one isolated maxilla, one dentary), teeth.[39]

A velociraptorine dromaeosaurid. Teeth previously referred to Campanian dromaeosaurids Saurornitholestes and Dromaeosaurus, frequently found throughout the formation, probably belong to this one species. Evans et al. conclude that there is little evidence for more than a single dromaeosaurid taxon, A. temertyorum, in the Hell Creek-Lance assemblages.[39]

Brodavis[40]

B. baileyi[40]

Left tarsometatarsus missing proximal end, trochleae II and III.[40]

A hesperornithiform.[40]

Dromaeosaurus[41]

D. cf. albertensis[41]

  • Montana
  • South Dakota

Teeth

Evans et al. conclude that there is little evidence for more than a single dromaeosaurid taxon, A. temertyorum, in the Hell Creek-Lance assemblages, which may render these taxa invalid.[39]

Saurornitholestes[41]

S. langstoni[41]

  • Montana
  • South Dakota
  • North Dakota

Teeth

Evans et al. conclude that there is little evidence for more than a single dromaeosaurid taxon, A. temertyorum, in the Hell Creek-Lance assemblages, which may render these taxa invalid.[39]

cf. Paronychodon[17]

Indeterminate

Teeth

Indeterminate troodontid

Richardoestesia[42]

R. isosceles

  • Montana
  • North Dakota
  • South Dakota

Teeth

Evans et al. conclude that there is little evidence for more than a single dromaeosaurid taxon, A. temertyorum, in the Hell Creek-Lance assemblages, which may render these taxa invalid.[39]

R. cf. gilmorei

  • North Dakota

Teeth

  • Indeterminate
  • South Dakota

Teeth

cf. Troodon[17]

T. formosus[17]

Teeth

Troodontid teeth similar to the older Troodon formosus

"Unnamed ornithurine B"[43]

Indeterminate[44]

Partial coracoid

An ornithurine possibly similar to Cimolopteryx[43][44]

"Unnamed ornithurine C"[43]

Indeterminate

Partial coracoid

An ornithurine, also present in the Fort Union Formation, the only individual bird species known to have survived the Cretaceous–Paleogene extinction[43]

"Unnamed ornithurine D"[43]

Indeterminate

Partial coracoid

An ornithurine[43]

"Unnamed hesperornithiform A"[43]

Indeterminate

Tarsometatarsus

A primitive hesperornithiform.[43] In addition to fossils from the Hell Creek Formation, Longrich, Tokaryk and Field (2011) assigned specimen RSM P 2315.1 from the Canadian Frenchman Formation to this taxon as well; [43] subsequently Martin, Kurochkin and Tokaryk (2012) made this particular specimen the holotype of the species Brodavis americanus.[40]

Pterosaurs[edit]

Pterosaurs of the Hell Creek Formation
Taxa Species Location Description Images

Quetzalcoatlus[46]

Q. northropi[47]

A single azhdarchid neck bone may belong to the genus Quetzalcoatlus, thought are not diagnostic to the generic level.[47]

Crocodylomorphs[edit]

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.
Crocodylomorphs reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes

Borealosuchus[48]

  • B. sternbergii[48]
  • Montana

Brachychampsa[48]

  • Montana

Thoracosaurus[48]

  • T. neocesariensis[48]

Turtles[edit]

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.
Turtles reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes

Adocus[49]

Indeterminate[49]

Compsemys[49]

C. victa[49]

Emarginachelys

E. cretacea

  • Montana

A relative of chelydrids.[51]

Eubaena[49]

E. cephalica[49]

Gamerabaena

G. sonsalla

  • North Dakota

Hoplochelys[51]

H. clark[51]

A kinosternoid related to the Central American river turtle.[51]

Trionyx[49]

Indeterminate[49]

Squamates[edit]

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.
squamates reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes

Cemeterius[52][53]

A platynotan lizard of uncertain phylogenetic placement, also known from the Lance Formation.[52]

Cerberophis[52][53]

An alethinophidian snake of uncertain phylogenetic placement.[52]

Obamadon[52][53]

A polyglyphanodontian lizard of uncertain phylogenetic placement. Also known from the Lance Formation.[52]

Peneteius[52]

A chamopsiid polyglyphanodontian lizard.[52]

Choristoderans[edit]

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.
Choristoderans reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes

Champsosaurus[48]

Mammals[edit]

Multituberculates[edit]

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.
Multituberculates reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Cimexomys[54]

A multituberculate of uncertain phylogenetic placement.

Cimolodon[54]

  • C. nitidus
  • C. sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

A cimolodontid multituberculate.

Cimolomys[54]

  • C. gracilis
  • C. cf. gracilis[54]
  • Montana
  • South Dakota[54]

A cimolomyid multituberculate.

Essonodon[54]

A cimolomyid multituberculate.

Meniscoessus[54]

  • M. conquistus
  • M. robustus
  • M. cf. robustus
  • M. sp.
  •  ?M. sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

A cimolomyid multituberculate.

Mesodma[54]

  • M. formosa
  • M. cf. formosa
  • M. hensleighi
  • M. cf. hensleighi
  • M. thompsoni
  • M. cf. thompsoni
  •  ?M sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

A neoplagiaulacid multituberculate.

?Neoplagiaulax[54]

  •  ?N. burgessi[54]

A neoplagiaulacid multituberculate.

Paracimexomys[54]

A multituberculate of uncertain phylogenetic placement.

Paressonodon[55]

A cimolomyid multituberculate.

Metatherians[edit]

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.
Metatherians reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Alphadon[54]

  • A. marshi
  • A. cf. marshi
  • A. wilsoni
  • A. cf. wilsoni
  • A. sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

An alphadontid.

Didelphodon[54]

  • D. padanicus
  • D. vorax
  • D. cf. vorax
  • D. sp.
  • cf. D. sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

A stagodontid.

Glasbius[54]

  • G. twitchelli
  • G. cf. twitchelli[54]

A glasbiid.

Leptalestes[56]

  • L. cooki
  • L. krejcii[56]
  • Montana
  • South Dakota

A pediomyid.

Nanocuris[55]

A deltatheridiid.

Nortedelphys

  • Montana
  • South Dakota

A herpetotheriid.

Pediomys[54]

  • Montana
  • South Dakota[54]

A pediomyid.

Protalphadon[54]

  • P. foxi
  • P. lulli[54]

An alphadontid.

Protolambda[56]

  • P. florencae
  • P. hatcheri[56]
  • Montana
  • North Dakota
  • South Dakota

A pediomyid.

Turgidodon[54]

An alphadontid.

Eutherians[edit]

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.
Eutherians reported from the Hell Creek Formation
Genus Species State Stratigraphic position Material Notes Images

Alostera[54]

  • A. saskatchewanensis[54]

An eutherian of uncertain phylogenetic placement.

Batodon[54]

A cimolestid eutherian.

Cimolestes[54]

  • C. cf. cerberoides
  • C. incisus
  • C. magnus
  • C. propalaeoryctes
  • C. stirtoni[54]
  • Montana
  • North Dakota[54]

A cimolestid eutherian.

Gypsonictops[54]

  • G. hypoconus
  • G. illuminatus
  • G. cf. illuminatus
  • G. sp.[54]
  • Montana
  • North Dakota
  • South Dakota[54]

A gypsonictopsid eutherian.

cf. Paranyctoides[54]

  • cf. Paranyctoides sp.[54]

A nyctitheriid eutherian.

Protungulatum[56]

An eutherian of uncertain phylogenetic placement; a basal eutherian or an arctocyonid condylarth.

Plants[edit]

Plants of the Hell Creek Formation
Genus Species Presence Description Images

Metasequoia

Indeterminate

Casts of Dawn Redwood seed cones are known from the Hell Creek.

Cobbania

C. corrugata

A prehistoric species of water lettuce, previously assigned to the genus Pistia.

Araucaria

A. araucana

Casts of Monkey-puzzle leaves are found in Hell Creek.

See also[edit]

Footnotes[edit]

  1. ^ Husson, D., Galbrun, B., Laskar, J., Hinnov, L. A., Thibault, N., Gardin, S., & Locklair, R. E. (2011). "Astronomical calibration of the Maastrichtian (late Cretaceous)". Earth and Planetary Science Letters 305 (3): 328–340. doi:10.1016/j.epsl.2011.03.008. 
  2. ^ a b Pearson, D. A., Schaefer, T., Johnson, K. R., Nichols, D. J., & Hunter, J. P. (2002). Vertebrate biostratigraphy of the Hell Creek formation in southwestern North Dakota and northwestern South Dakota. Hartman et al, 145-167.
  3. ^ Johnson, K. R., Nichols, D. J., & Hartman, J. H. (2002). Hell Creek Formation: A 2001 synthesis. The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the northern Great Plains: Geological Society of America Special Paper, 361, 503-510.
  4. ^ Listed as "cf. Barbourula sp." in "Class Amphibia," Estes and Berberian, (1970). Page 4.
  5. ^ a b c d e f g h i j k l m n o p "Class Amphibia," in Estes and Berberian, (1970). Page 4.
  6. ^ a b c d e f g h i "Class Amphibia," in Estes and Berberian, (1970). Page 4. All taxa listed occur in Montana, see page 1.
  7. ^ Listed as "Eopelobates? sp." in "Class Amphibia," Estes and Berberian, (1970). Page 4.
  8. ^ a b c d David G. Demar Jr. (2013). "A new fossil salamander (Caudata, Proteidae) from the Upper Cretaceous (Maastrichtian) Hell Creek Formation, Montana, U.S.A.". Journal of Vertebrate Paleontology 33 (3): 588–598. doi:10.1080/02724634.2013.734887. 
  9. ^ a b c d e f g h i j k l m n o p "Class Osteichthyes," in Estes and Berberian, (1970). Page 3.
  10. ^ a b c d e f g h "Class Osteichthyes," in Estes and Berberian, (1970). Page 3. All taxa listed occur in Montana, see page 1.
  11. ^ a b c d "Class Osteichthyes," in Estes and Berberian, (1970). Page 4.
  12. ^ a b c "Class Osteichthyes," in Estes and Berberian, (1970). Page 4. All taxa listed occur in Montana, see page 1.
  13. ^ a b Listed as "cf. Paralbula casei" in "Class Osteichthyes," Estes and Berberian, (1970). Page 4.
  14. ^ a b c d "Class Chondrichthyes," in Estes and Berberian, (1970). Page 3.
  15. ^ a b "Class Chondrichthyes," in Estes and Berberian, (1970). Page 3. All taxa listed occur in Montana, see page 1.
  16. ^ a b c d e f g h i j k l m Todd D. Cook, Michael G. Newbrey, Donald B. Brinkman and James I. Kirkland (2014). "Euselachians from the freshwater deposits of the Hell Creek Formation of Montana". GSA Special Papers 503: 229–246. doi:10.1130/2014.2503(08). 
  17. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi "Dinosaur distribution (Late Cretaceous; North America; Montana)." Weishampel, et al. (2004). Page 584.
  18. ^ a b c d e f g "Dinosaur distribution (Late Cretaceous; North America; North Dakota)." Weishampel, et al. (2004). Page 585.
  19. ^ a b c d e f g h i j k l m n o p q r "Dinosaur distribution (Late Cretaceous; North America; South Dakota)." Weishampel, et al. (2004). Page 586.
  20. ^ Listed as "Leptoceratops c.f. gracilis" in "Dinosaur distribution (Late Cretaceous; North America; Montana)." Weishampel, et al. (2004). Page 584.
  21. ^ Nicholas R. Longrich (2011). "Titanoceratops ouranous, a giant horned dinosaur from the Late Campanian of New Mexico". Cretaceous Research 32. doi:10.1016/j.cretres.2010.12.007. 
  22. ^ Scannella, J. and Horner, J.R. (2010). "Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny." Journal of Vertebrate Paleontology, 30(4): 1157 - 1168. doi:10.1080/02724634.2010.483632
  23. ^ "Table 23.1," in Weishampel, et al. (2004). Page 496.
  24. ^ a b Campione, N.E. and Evans, D.C. (2011). "Cranial Growth and Variation in Edmontosaurs (Dinosauria: Hadrosauridae): Implications for Latest Cretaceous Megaherbivore Diversity in North America." PLoS ONE, 6(9): e25186. doi:10.1371/journal.pone.0025186
  25. ^ a b Listed as "?Parasaurolophus walkeri" in "Dinosaur distribution (Late Cretaceous; North America; Montana)." Weishampel, et al. (2004). Page 584.
  26. ^ a b Listed as "?Thescelosaurus garbanii" in "Dinosaur distribution (Late Cretaceous; North America; Montana)." Weishampel, et al. (2004). Page 584.
  27. ^ Noted as being present, although misspelled as "Thescelosaurus garbani, in " "Dinosaur distribution (Late Cretaceous; North America; South Dakota)." Weishampel, et al. (2004). Page 586.
  28. ^ Boyd, Brown, et al. (2009)
  29. ^ Listed as "c.f. Thescelosaurus sp." in "Dinosaur distribution (Late Cretaceous; North America; North Dakota)." Weishampel, et al. (2004). Page 585.
  30. ^ a b c d Bakker et al. (2006)
  31. ^ "Table 21.1," in Weishampel, et al. (2004). Page 465.
  32. ^ Hutchinson and Chiappe, 1998. The first known alvarezsaurid (Theropoda: Aves) from North America. Journal of Vertebrate Paleontology. 18(3), 447-450.
  33. ^ "Table 5.1," in Weishampel, et al. (2004). Page 113.
  34. ^ Triebold, 1997. The Sandy Site: Small Dinosaurs from the Hell Creek Formation of South Dakota. in Wolberg, Stump and Rosenberg (eds). Dinofest International: Proceedings of a Symposium sponsored by Arizona
  35. ^ Listed as "?Ornithomimus sp." in "Dinosaur distribution (Late Cretaceous; North America; North Dakota)." Weishampel, et al. (2004). Page 585.
  36. ^ a b Longrich (2008), pages 983-996.
  37. ^ Listed as "c.f. Struthiomimus sp." in "Dinosaur distribution (Late Cretaceous; North America; North Dakota)." Weishampel, et al. (2004). Page 585.
  38. ^ a b Lamanna, M. C.; Sues, H. D.; Schachner, E. R.; Lyson, T. R. (2014). "A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America". PLoS ONE 9 (3): e92022. doi:10.1371/journal.pone.0092022.  edit
  39. ^ a b c d e f g h Evans, D. C.; Larson, D. W.; Currie, P. J. (2013). "A new dromaeosaurid (Dinosauria: Theropoda) with Asian affinities from the latest Cretaceous of North America". Naturwissenschaften. doi:10.1007/s00114-013-1107-5.  edit
  40. ^ a b c d e f Larry D. Martin, Evgeny N. Kurochkin and Tim T. Tokaryk (2012). "A new evolutionary lineage of diving birds from the Late Cretaceous of North America and Asia". Palaeoworld 21. doi:10.1016/j.palwor.2012.02.005. 
  41. ^ a b c d "Dinosaur distribution (Late Cretaceous; North America; Yukon Territory, Canada)." In: Weishampel et al. Page 578.
  42. ^ Referenced by the original, obsolete spelling "Ricardoestesia" in "Dinosaur distribution (Late Cretaceous; North America; North Dakota)." Weishampel, et al. (2004). Page 585.
  43. ^ a b c d e f g h i j Longrich, N.R., Tokaryk, T. and Field, D.J. (2011). "Mass extinction of birds at the Cretaceous–Paleogene (K–Pg) boundary." Proceedings of the National Academy of Sciences, 108(37): 15253-15257. doi:10.1073/pnas.1110395108
  44. ^ a b "Class Aves," in Estes and Berberian, (1970). Page 7.
  45. ^ "Class Aves," in Estes and Berberian, (1970). Page 7. All taxa listed occur in Montana, see page 1.
  46. ^ Listed as "cf. Quetzalcoatlus sp." in Henderson and Peterson (2006) 192–195.
  47. ^ a b c Henderson and Peterson (2006) 192–195.
  48. ^ a b c d e f g h R. Matsumoto, S. E. Evans (2010). "Choristoderes and the freshwater assemblages of Laurasia". Journal of Iberian Geology 36 (2): 253–274. 
  49. ^ a b c d e f g h "Order Testudinata," in Estes and Berberian, (1970). Page 5.
  50. ^ a b c d "Order Testudinata," in Estes and Berberian, (1970). Page 5. All taxa listed occur in Montana, see page 1.
  51. ^ a b c d e Georgia E. Knauss, Walter G. Joyce, Tyler R. Lyson and Dean Pearson (2011). "A new kinosternoid from the Late Cretaceous Hell Creek Formation of North Dakota and Montana and the origin of the Dermatemys mawii lineage". Paläontologische Zeitschrift 85 (2): 124–142. doi:10.1007/s12542-010-0081-x. 
  52. ^ a b c d e f g h i j k l m n o p Nicholas R. Longrich, Bhart-Anjan S. Bhullar and Jacques A. Gauthier (2012). "Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary". Proceedings of the National Academy of Sciences of the United States of America 109 (52): 21396–21401. doi:10.1073/pnas.1211526110. PMC 3535637. PMID 23236177. 
  53. ^ a b c d e f Nicholas R. Longrich, Bhart-Anjan S. Bhullar and Jacques A. Gauthier (2013). "Correction for "Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary," by Nicholas R. Longrich, Bhart-Anjan S. Bhullar, and Jacques A. Gauthier, which appeared in issue 52, December 26, 2012, of Proc Natl Acad Sci USA (109:21396–21401; first published December 10, 2012; 10.1073/pnas.1211526110)". Proceedings of the National Academy of Sciences of the United States of America 110 (16): 6608. doi:10.1073/pnas.1303907110. 
  54. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be Zofia Kielan-Jaworowska, Richard L. Cifelli, and Zhe-Xi Luo, Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure, Columbia University Press, New York, 2004 ISBN 0-231-11918-6, p. 98-99
  55. ^ a b c d e Gregory P. Wilson (2013). "Mammals across the K/Pg boundary in northeastern Montana, U.S.A.: dental morphology and body-size patterns reveal extinction selectivity and immigrant-fueled ecospace filling". Paleobiology 39 (3): 429–469. doi:10.1666/12041. 
  56. ^ a b c d e f g J. David Archibald, Yue Zhang, Tony Harper and Richard L. Cifelli (2011). "Protungulatum, confirmed Cretaceous occurrence of an otherwise Paleocene eutherian (placental?) mammal". Journal of Mammalian Evolution 18 (3): 153–161. doi:10.1007/s10914-011-9162-1. 
  57. ^ Thomas E. Williamson, Stephen L. Brusatte, Thomas D. Carr, Anne Weil and Barbara R. Standhardt (2012). "The phylogeny and evolution of Cretaceous–Palaeogene metatherians: cladistic analysis and description of new early Palaeocene specimens from the Nacimiento Formation, New Mexico". Journal of Systematic Palaeontology 10 (4): 625–651. doi:10.1080/14772019.2011.631592. 

References[edit]

  • Bakker, R. T., Sullivan, R. M., Porter, V., Larson, P. and Saulsbury, S.J. (2006). "Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota." in Lucas, S. G. and Sullivan, R. M., eds., Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35, pp. 331–345. [1]
  • Boyd, Clint A.; Brown, Caleb M.; Scheetz, Rodney D.; Clarke; Julia A. (2009). "Taxonomic revision of the basal neornithischian taxa Thescelosaurus and Bugenasaura". Journal of Vertebrate Paleontology 29 (3): 758–770. doi:10.1671/039.029.0328. 
  • Estes, R., and P. Berberian. 1970. Paleoecology of a late Cretaceous vertebrate community from Montana. Breviora volume 343, 35 pages.
  • Henderson, M.D. and Peterson, J.E. "An azhdarchid pterosaur cervical vertebra from the Hell Creek Formation (Maastrichtian) of southeastern Montana." Journal of Vertebrate Paleontology, 26(1): 192–195.
  • Longrich, N. (2008). "A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: Implications for the study of dissociated dinosaur remains." Palaeontology, 54(1): 983-996.
  • Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropoda) dinosaurs from Montana. pp. 42–57 in D. H. Tanke and K. Carpenter (eds.), Mesozoic Vertebrate Life. Indiana University Press, Indianapolis, Indiana.
  • Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.

External links[edit]