Judith River Formation

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Judith River Formation
Stratigraphic range: Campanian, 80–75Ma
[1]
Leonardo mummified brachylophosaurus.jpg
"Leonardo," a rare intact mummified Brachylophosaurus canadensis uncovered in the Judith River Formation.
Type Geological formation
Unit of Judith River Group
Sub-units Birch Lake Member, Ribstone Creek Member, Brosseau Member, Victoria Member
Underlies Bearpaw Formation
Overlies Claggett Formation, Pakowki Formation
Thickness max 360 meters (1,180 ft)[2]
Lithology
Primary Siltstone and sandstone
Other Coal, coquinas
Location
Coordinates 47°40′N 109°39′W / 47.667°N 109.650°W / 47.667; -109.650 (Judith River Formation)Coordinates: 47°40′N 109°39′W / 47.667°N 109.650°W / 47.667; -109.650 (Judith River Formation)
Region Montana
Country  United States
Type section
Named for Confluence of Judith River and Missouri River
Named by F.V. Hayden, 1871;[3] F.B. Meek, 1876.[4]

The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the upper Cretaceous, between 80 and 75 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[1] and the Oldman Formation of Alberta.[5] 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 (such as Monoclonius). Modern work has found nearly complete skeletons of the hadrosaurid Brachylophosaurus.

Lithology[edit]

The Judith River Formation is composed of mudstone, siltstone and sandstone.[2] Coal beds, bentonite and coquinas are also observed.

Fauna[edit]

Faunal list follows a review published by Ashok Sahni in 1972 unless otherwise noted.[6]

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[edit]

There are three potential species of discoglossid frogs. Hip bones, possibly representing a North American member of the European spadefoot toad family are also known from the formation.

Amphibians of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Habrosaurus

H. dilatus

A siren.

Lisserpeton

L. bairdi

A scapherpetonid salamander.

Opisthotriton

O. kayi

A possible lungless salamander.

Prodesmodon

P. copei

A lungless salamander.

Scapherpeton

S. tectum

A scapherpetonid salamander.

Bony fish[edit]

Bony fishes of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Belonostomus

Belonostomus longirostris

An aspidorhynchiform.

Kindleia

K. fragosa

A bowfin.

Lepisosteus

L. occidentalis

A gar.

?Paralbula

?P. sp.

A bonefish.

Cartilaginous fish[edit]

Cartilaginous fishes of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Myledaphus

M. bipartitus

A stingray.

Ornithischian dinosaurs[edit]

Ornithischians reported from the Judith River Formation
Genus Species Location Stratigraphic position Material Notes Images

Albertaceratops

A. nesmoi[7]

A ceratopsid

Avaceratops

A. lammersi[7]

"[Two] partial skulls, skeleton, juvenile,"[8] type specimen

A ceratopsid

Brachylophosaurus

B. canadensis

A hadrosaurid

Ceratops

C. montanus

"occipital condyle, paired horn cores,"[9] type specimen

A dubious ceratopsid

Diclonius

D. calamarius

"Teeth."[10]

Nomen dubium

D. pentagonius

"Fragmentary dentary with teeth,"[10] type specimen

A dubious hadrosaurid

D. perengulatus

"Teeth."[10]

Nomen dubium

Dysganus

D. bicarinatus

"Isolated teeth."[9]

Nomen dubium

D. encaustus

"Single tooth and [five] tooth fragments."[10] "Isolated teeth."[9]

Nomen dubium

D. haydenianus

"Isolated teeth."[9]

Nomen dubium

D. peiganus

"Tooth."[9]

Nomen dubium

Hadrosaurus

H. paucidens

Reclassified as Lambeosaurus? paucidens

Judiceratops[11]

J. tigris[11]

A ceratopsid

?"Kritosaurus"

?"K." breviceps

A hadrosaurid

?Lambeosaurus

?L. paucidens

"Squamosal, maxilla."[10]

A hadrosaurid

Medusaceratops

M. lokii[12]

Bonebed[12]

A ceratopsid

Mercuriceratops

M. gemini[13]

"one apomorphic squamosal"[13]

A ceratopsid

Monoclonius

M. crassus[7]

"[Five] skulls, [one] complete."[8] Type specimen

A dubious ceratopsid

Paleoscincus

P. costatus

"Tooth,"[14] type specimen

A dubious ankylosaur

Pteropelyx

P. grallipes

"Skeleton lacking skull."[15]

A dubious hadrosaurid

Trachodon

T. mirabilis

Isolated teeth, type specimen

A dubious hadrosaurid

Choristoderes[edit]

Choristoderes of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Champsosaurus

C. sp.

Crocodilians[edit]

Crocodillians of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Brachychampsa

B. montana

An alligatorid.

Leidyosuchus

L. canadensis

An alligatorid.

Lizards[edit]

Lizards of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Chamops

C. segnis

A whiptail.

Exostinus

E. lancensis

A knob-scaled lizard.

Leptochamops

L. denticulatus

A whiptail.

Paraderma

P. bogerti

A parasaniwid.

Parasaniwa

P. wyomingensis

A parasaniwid.

Theropod dinosaurs[edit]

An unnamed tyrannosaurine is known from the formation.[16]

Theropods reported from the Judith River Formation
Genus Species Location Stratigraphic position Material Notes Images

Aublysodon

A. lateralis

"Isolated teeth,"[17][18] type specimen

Junior synonym of Deinodon horridus[6]

A. mirandus

Teeth, type specimen

Possible junior synonym of Deinodon horridus[6]

Coniornis

C. altus

Partial tibiotarsus

One of the only known freshwater occurrences of a hesperornithid.[19]

Deinodon

D. falculus

Teeth

Isolated tyrannosaur teeth classified in the dubious genus Deinodon

D. hazenianus

Teeth

Junior synonym of Deinodon horridus[6]

D. horridus

"Teeth,"[18] type specimen

Isolated tyrannosaur teeth that formed the basis of the dubious genus Deinodon

D. incrassatus

Teeth

Junior synonym of Deinodon horridus[6]

D. lateralis

Junior synonym of Deinodon horridus[6]

Dromaeosaurus

D. albertensis

Teeth

A dromaeosaurid, also found in the Dinosaur Park

D. explanatus

"Tooth."[20]

Possible relative of Saurornitholestes

D. laevifrons

"Tooth."[20]

Possible relative of Saurornitholestes

Ornithomimus

O. tenuis

"Fragmentary metatarsal."[21]

A possible troodontid or juvenile tyrannosaurid

Paronychodon

P. lacustris

Teeth, type specimen

An indeterminate maniraptoran, also found in the Dinosaur Park, Milk River, and Kirtland Formations

Troodon

T. formosus

Teeth (type specimen), vertebra, egg

A troodontid, also found in the Oldman, Dinosaur Park, and Two Medicine Formations

Zapsalis[22]

Z. abradens

"Teeth,"[20] type specimen

A dromaeosaurid

Turtles[edit]

Turtles of the Judith River Formation
Genus Species Location Stratigraphic position Abundance Notes Images

Basilemys

B. sp.

A Mesoamerican river turtle.

Relationship with other units[edit]

The Judith River Formation conformably overlies the Claggett Formation and Pakowki Formation. It is overlain by the Bearpaw Formation.[2] It is equivalent to the Belly River Formation in the southern Canadian Rockies foothills, the Lea Park Formation in central Alberta and the Wapiti Formation in the northwestern plains. To the east, it correlates with the sum of Oldman Formation and Foremost Formation.

Sub-divisions[edit]

The Birch Lake Member and Ribstone Creek Member are sandstone units recognized inside the Judith River Formation. Other informal subdivisions include the Brosseau Member and Victoria Member, which are considered obsolete due to their inconsistent lateral distribution.

See also[edit]

References[edit]

  1. ^ a b Sullivan, R.M. and Lucas, S. G. (2006). "The Kirtlandian land-vertebrate “age”–faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America." Pp. 7-29 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.
  2. ^ a b c Lexicon of Canadian Geological Units. "Judith River Formation". Retrieved 2009-02-06. 
  3. ^ Hayden, F.V., 1871. Geology of the Missouri Valley: Preliminary report (4th annual) of the Geol. Surv. of Wyoming and portions of contiguous territories.
  4. ^ Meek, Fielding Bradford, 1876. A report on the invertebrate Cretaceous and Tertiary fossils of the upper Missouri country, Hayden, F.V., Geologist in Charge; United States Geologic and Geographic Survey of the Territories, vol. 9, page 629
  5. ^ Eberth, David A. (1997). "Judith River Wedge". In Currie, Philip J. & Padian, Kevin (eds.). Encyclopedia of Dinosaurs. San Diego: Academic Press. pp. 199–204. ISBN 0-12-226810-5. 
  6. ^ a b c d e f Sahni, A. (1972). "The vertebrate fauna of the Judith River Formation, Montana." Bulletin of the AMNH, v. 147 article 6: 321-415.
  7. ^ a b c Ryan and Evans, 2005
  8. ^ a b "Table 23.1," in Weishampel, et al. (2004). Page 495.
  9. ^ a b c d e "Table 23.1," in Weishampel, et al. (2004). Page 496.
  10. ^ a b c d e "Table 20.1," in Weishampel, et al. (2004). Page 442.
  11. ^ a b Nicholas R. Longrich (2013). "Judiceratops tigris, a New Horned Dinosaur from the Middle Campanian Judith River Formation of Montana". Bulletin of the Peabody Museum of Natural History 54 (1): 51–65. doi:10.3374/014.054.0103. 
  12. ^ a b Ryan, Michael J.; Russell, Anthony P., and Hartman, Scott. (2010). "A New Chasmosaurine Ceratopsid from the Judith River Formation, Montana", In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, 656 pp. ISBN 0-253-35358-0.
  13. ^ a b Ryan, Michael J.; Evans, David C.; Currie, Phillip J.; Loewen, Mark A. (2014). "A New chasmosaurine from northern Laramidia expands frill disparity in ceratopsid dinosaurs". Naturwissenschaften. doi:10.1007/s00114-014-1183-1
  14. ^ "Table 17.1," in Weishampel, et al. (2004). Page 368.
  15. ^ "Table 20.1," in Weishampel, et al. (2004). Page 443.
  16. ^ Stein and Triebold (2005). "Preliminary analysis of a sub-adult tyrannosaurid skeleton, known as "Sir William" from the Judith River Formation of Petroleum County, Montana." In The origin, systematics, and paleobiology of Tyrannosauridae, a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University, p. 27-28.
  17. ^ "Table 4.1," in Weishampel, et al. (2004). Page 78.
  18. ^ a b "Table 5.1," in Weishampel, et al. (2004). Page 114.
  19. ^ Fox, R.C. (1974). "A middle Campanian, nonmarine occurrence of the Cretaceous toothed bird Hesperornis Marsh." Canadian Journal of Earth Sciences, 11: 1335-1338.
  20. ^ a b c "Table 9.1," in Weishampel, et al. (2004). Page 186.
  21. ^ "Table 6.1," in Weishampel, et al. (2004). Page 139.
  22. ^ Larson, D. W.; Currie, P. J. (2013). "Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time". In Evans, Alistair Robert. PLoS ONE 8: e54329. doi:10.1371/journal.pone.0054329. edit