Judith River Formation

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Judith River Formation
Stratigraphic range: Campanian, 79.8–75.2 Ma
↓
[1]
Leonardo mummified brachylophosaurus.jpg
"Leonardo," a rare intact mummified Brachylophosaurus canadensis uncovered in the Judith River Formation.
TypeGeological formation
Unit ofJudith River Group
Sub-unitsParkman Sandstone Member, McClelland Ferry Member, Coal Ridge Member, Woodhawk Member
UnderliesBearpaw Formation
OverliesClaggett Formation, Pakowki Formation
Thicknessmax 360 meters (1,180 ft)[2]
Lithology
PrimarySiltstone and sandstone
OtherCoal, coquinas
Location
Coordinates47°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 forConfluence of Judith River and Missouri River
Named byF.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 Late 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[]

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

Relationship with other units[]

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.

Sub-divisions[]

The Judith River Formation is divided into four members, the Parkman Sandstone Member, the McClelland Ferry Member, the Coal Ridge member, and the Woodhawk Member.[6] The McClelland Ferry Member is believed to be equivalent to the Oldman Formation, with the Coal Ridge Member equivalent to the Dinosaur Park Formation, but radiometric dates from the three formations do not support this, although this may be a problem with the dates themselves.[7]

Fauna[]

Faunal list follows a review published by Ashok Sahni in 1972 unless otherwise noted.[8]

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[]

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 salamander.

Opisthotriton

O. kayi

A possible lungless salamander.

Prodesmodon

P. copei

A lungless salamander.

Scapherpeton

S. tectum

A scapherpetonid salamander.

Bony fish[]

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

Belonostomus

Belonostomus longirostris

An aspidorhynchiform.

K. fragosa

A bowfin.

Lepisosteus

L. occidentalis

A gar.

?Paralbula

?P. sp.

A bonefish.

Cartilaginous fish[]

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

Myledaphus

M. bipartitus

A stingray.

Ornithischian dinosaurs[]

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

Albertaceratops

A. nesmoi[9]

Reclassified as Medusaceratops lokii

Avaceratops
Brachylophosaurus
Edmontonia
Judiceratops
Medusaceratops
Mercuriceratops
Monoclonius
Probrachylophosaurus
Spiclypeus
Zuul

Avaceratops

A. lammersi[9]

lower McClelland Ferry

"[Two] partial skulls, skeleton, juvenile,"[10] type specimen

A ceratopsid

Brachylophosaurus

B. canadensis

middle McClelland Ferry

A hadrosaurid which was one of the more common dinosaurs in the area.[11]

Ceratops

C. montanus

"occipital condyle, paired horn cores,"[12] type specimen

A dubious ceratopsid

Diclonius

D. calamarius

"Teeth."[13]

Nomen dubium

D. pentagonius

"Fragmentary dentary with teeth,"[13] type specimen

A dubious hadrosaurid

D. perengulatus

"Teeth."[13]

Nomen dubium

Dysganus

D. bicarinatus

"Isolated teeth."[12]

Nomen dubium

D. encaustus

"Single tooth and [five] tooth fragments."[13] "Isolated teeth."[12]

Nomen dubium

D. haydenianus

"Isolated teeth."[12]

Nomen dubium

D. peiganus

"Tooth."[12]

Nomen dubium

Edmontonia E. longiceps Isolated teeth[14]

Hadrosaurus

H. paucidens

Reclassified as Lambeosaurus? paucidens

Judiceratops[15]

J. tigris[15]

A ceratopsid

?"Kritosaurus"

?"K." breviceps

A dubious hadrosaurid

?Lambeosaurus

?L. paucidens

"Squamosal, maxilla."[13]

Nomen dubium. An indeterminate lambeosaurine.[16]

Medusaceratops

M. lokii[17]

lower McClelland Ferry

Bonebed[17]

A ceratopsid

Mercuriceratops

M. gemini[18]

lower Coal Ridge

"one apomorphic squamosal"[18]

A ceratopsid

Monoclonius

M. crassus[9]

lower Coal Ridge

"[Five] skulls, [one] complete."[10] Type specimen

A dubious ceratopsid

Paleoscincus

P. costatus

"Tooth,"[19] type specimen

A dubious ankylosaur

Probrachylophosaurus

P. bergei

lower McClelland Ferry

A brachylophosaurin hadrosaur

Pteropelyx

P. grallipes

"Skeleton lacking skull."[20]

A dubious hadrosaurid

Trachodon

T. mirabilis

Isolated teeth, type specimen

A dubious hadrosaurid

Spiclypeus S. shipporum McClelland Ferry[7] Partial skull, vertebrae, ribs, humerus, ilium, femur, tibia, and fibula. A ceratopsid
Zuul Z. crurivastator middle Coal Ridge Cranial and postcranial skeletal remains and soft tissue, type specimen An ankylosaurid

Choristoderes[]

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

Champsosaurus

C. sp.

Champsosaurus

Crocodilians[]

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

Brachychampsa

B. montana

An alligatorid.
Brachychampsa
Deinosuchus

Leidyosuchus

L. canadensis

An alligatorid.
Deinosuchus D. hatcheri[21]

Lizards[]

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

Chamops

C. segnis

A whiptail.

E. lancensis

A knob-scaled lizard.

L. denticulatus

A whiptail.

P. bogerti

A parasaniwid.

P. wyomingensis

A parasaniwid.

Theropod dinosaurs[]

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

Aublysodon

A. lateralis

"Isolated teeth,"[22][23] type specimen

Junior synonym of Deinodon horridus[8]

Gorgosaurus
Daspletosaurus
Hesperornis
Dromaeosaurus

A. mirandus

Teeth, type specimen

Possible junior synonym of Deinodon horridus[8]

Hesperornis

H. altus

Partial tibiotarsus

One of the only known freshwater occurrences of a hesperornithid.[24]

Daspletosaurus D. torosus Maxilla[25] A large tyrannosaurid.

Deinodon

D. falculus

Teeth

Isolated tyrannosaur teeth classified in the dubious genus Deinodon

D. hazenianus

Teeth

Junior synonym of Deinodon horridus[8]

D. horridus

"Teeth,"[23] type specimen

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

D. incrassatus

Teeth

Junior synonym of Deinodon horridus[8]

D. lateralis

Junior synonym of Deinodon horridus[8]

Dromaeosaurus

D. albertensis

Teeth

A dromaeosaurid, also found in the Dinosaur Park Formation

D. explanatus

"Tooth."[26]

Possible relative of Saurornitholestes

D. laevifrons

"Tooth."[26]

Possible relative of Saurornitholestes

Gorgosaurus G. libratus Postorbital[25] A large tyrannosaurid, also found in the Dinosaur Park Formation and possibly the Two Medicine Formation.

Ornithomimus

O. tenuis

"Fragmentary metatarsal."[27]

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), egg

A troodontid, possibly dubious.

Zapsalis[28]

Z. abradens

"Teeth,"[26] type specimen

A dromaeosaurid

Turtles[]

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

Basilemys

B. sp.

A Mesoamerican river turtle.

See also[]

  • List of dinosaur-bearing rock formations

References[]

  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. 379–380. ISBN 0-12-226810-5.
  6. ^ Rogers, Raymond R.; Kidwell, Susan M.; Deino, Alan L.; Mitchell, James P.; Nelson, Kenneth; Thole, Jeffrey T. (2016-01-01). "Age, Correlation, and Lithostratigraphic Revision of the Upper Cretaceous (Campanian) Judith River Formation in Its Type Area (North-Central Montana), with a Comparison of Low- and High-Accommodation Alluvial Records". The Journal of Geology. 124 (1): 99–135. doi:10.1086/684289. ISSN 0022-1376. S2CID 130555911.
  7. ^ 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.
  8. ^ 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.
  9. ^ a b c Ryan and Evans, 2005
  10. ^ a b "Table 23.1," in Weishampel, et al. (2004). Page 495.
  11. ^ Trexler, David; Murphy, Nate; Thompson, Mark (June 2007). ""Leonardo," a Mummified Brachylophosaurus (Ornithischia: Hadrosauridae) from the Judith River Formation of Montana". In Carpenter, Kenneth (ed.). Horns and Beaks. IU Office of Scholarly Publishing Herman B Wells Library E350 1320 E 10th Street E4 Bloomington, IN 47405-3907: Indiana University Press. pp. 117–133.CS1 maint: location (link)
  12. ^ a b c d e "Table 23.1," in Weishampel, et al. (2004). Page 496.
  13. ^ a b c d e "Table 20.1," in Weishampel, et al. (2004). Page 442.
  14. ^ Sahni, Ashok (1972). "The vertebrate fauna of the Judith River Formation, Montana. Bulletin of the AMNH ; v. 147, article 6". hdl:2246/1099. Cite journal requires |journal= (help)
  15. ^ 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. S2CID 129801786.
  16. ^ Prieto-Márquez, Alberto; Weishampel, David B.; Horner, John R. (2006). "The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus" (PDF). Acta Palaeontologica Polonica. 51 (1): 77–98.
  17. ^ 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.
  18. ^ 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
  19. ^ "Table 17.1," in Weishampel, et al. (2004). Page 368.
  20. ^ "Table 20.1," in Weishampel, et al. (2004). Page 443.
  21. ^ Schwimmer, David (2002). King of the Crocodylians: The Paleobiology of Deinosuchus. 601 North Morton Street, Bloomington, IN: Indiana University Press. p. 200.CS1 maint: location (link)
  22. ^ "Table 4.1," in Weishampel, et al. (2004). Page 78.
  23. ^ a b "Table 5.1," in Weishampel, et al. (2004). Page 114.
  24. ^ Fox, R.C. (1974). "A middle Campanian, nonmarine occurrence of the Cretaceous toothed bird Hesperornis Marsh." Canadian Journal of Earth Sciences, 11: 1335-1338.
  25. ^ a b Carr, Thomas D. (2018). "Significant geographic range extension for the sympatric tyrannosaurids Albertosaurus libratus and Daspletosaurus torosus from the Judith River Formation (Late Campanian) of northern Montana" (PDF). Journal of Vertebrate Paleontology. 38 (Supplement 1): 102.
  26. ^ a b c "Table 9.1," in Weishampel, et al. (2004). Page 186.
  27. ^ "Table 6.1," in Weishampel, et al. (2004). Page 139.
  28. ^ 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
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