Judith River Formation

Judith River Formation
Stratigraphic range: Campanian, 80–75 Ma
↓
[1]
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
Named for Confluence of Judith River and Missouri River
Named by F.V. Hayden, 1871;[3] F.B. Meek, 1876.[4]
Region Montana, Alberta, Saskatchewan
Country  United States

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 the Two Medicine Formation of Montana and the Belly River Group of Alberta.[1] 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.

Contents

Lithology

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

Fauna

Faunal list follows a review published by Ashok Sahni in 1972 unless otherwise noted.[5]

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 scapherpetonid 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.

Kindleia

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 Stratigraphic position Material Notes Images

Albertaceratops

A. nesmoi[6]

A ceratopsid

Avaceratops

A. lammersi[6]

"[Two] partial skulls, skeleton, juvenile,"[7] type specimen

A ceratopsid

Brachylophosaurus

B. canadensis

A hadrosaurid

Ceratops

C. montanus

"Occipital condyle, paired horn cores,"[8] type specimen

A dubious ceratopsid

Diclonius

D. calamarius

"Teeth."[9]

Nomen dubium

D. pentagonius

"Fragmentary dentary with teeth,"[9] type specimen

A dubious hadrosaurid

D. perengulatus

"Teeth."[9]

Nomen dubium

Dysganus

D. bicarinatus

"Isolated teeth."[8]

Nomen dubium

D. encaustus

"Single tooth and [five] tooth fragments."[9] "Isolated teeth."[8]

Nomen dubium

D. haydenianus

"Isolated teeth."[8]

Nomen dubium

D. peiganus

"Tooth."[8]

Nomen dubium

Hadrosaurus

H. paucidens

Reclassified as Lambeosaurus? paucidens

Edmontonia

E. longiceps

Tooth

 Isolated tooth possibly belonging to Edmontonia

Euoplocephalus

E. tutus

?"Kritosaurus"

?"K." breviceps

A hadrosaurid

?Lambeosaurus

?L. paucidens

"Squamosal, maxilla."[9]

A hadrosaurid

Medusaceratops

M. lokii[10]

Bonebed[10]

A ceratopsid

Monoclonius

M. crassus[6]

"[Five] skulls, [one] complete."[7] Type specimen

A ceratopsid

"M. fissus"

"Isolated pterygoid."[8]

Nomen nudum

"M. recurvicornis"

"Braincase, [three] horns, isolated fragments."[8]

Nomen nudum

"M. sphenocerus"

"Nasal horn, premaxilla."[8]

Nomen nudum

Paleoscincus

P. costatus

"Tooth,"[11] type specimen

A dubious ankylosaur

Pteropelyx

P. grallipes

"Skeleton lacking skull."[12]

A dubious hadrosaurid

Stegoceras

?S. validum

Isolated teeth possibly belonging to Stegoceras or another pachycephalosaur

Thescelosaurus

Indeterminate

Isolated teeth possibly belonging to Thescelosaurus.

Trachodon

T. mirabilis

Isolated teeth, type specimen

A dubious hadrosaurid

Choristoderes

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

Champsosaurus

C. sp.

Crocodilians

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

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

An unnamed tyrannosaurine is known from the formation.[13]

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

Aublysodon

A. lateralis

"Isolated teeth,"[14][15] type specimen

Isolated tyrannosaur teeth assigned to the dubious genus Aublysodon

A. mirandus

Teeth, type specimen

Coniornis

C. altus

Partial tibiotarsus

One of the only known freshwater occurrences of a hesperornithid.[16]

Deinodon

D. falculus

Teeth

Isolated tyrannosaur teeth classified in the dubious genus Deinodon

D. hazenianus

Teeth

Isolated tyrannosaur teeth classified in the dubious genus Deinodon

D. horridus

"Teeth,"[15] type specimen

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

D. incrassatus

Teeth

Isolated tyrannosaur teeth classified in the dubious genus Deinodon

D. lateralis

Junior synonym of Aublysodon lateralis

Dromaeosaurus

D. albertensis

Teeth

A dromaeosaurid, also found in the Dinosaur Park, Mesaverde, and Prince Creek Formations

D. explanatus

"Tooth."[17]

D. falculus

Junior synonym of Deinodon falculus

D. laevifrons

"Tooth."[17]

Dryptosaurus

D. explanatus (formerly Laelaps, preoccupied)

Reclassified as Dromaeosaurus explanatus

D. falculus (formerly Laelaps, preoccupied)

Junior synonym of Deinodon falculus

D. hazenianus (formerly Laelaps, preoccupied)

Junior synonym of Deinodon hazenianus

D. incrassatus (formerly Laelaps, preoccupied)

Junior synonym of Deinodon incrassatus

D. laevifrons (formerly Laelaps, preoccupied)

Reclassified as Dromaeosaurus laevifrons

Gorgosaurus

G. libratus

Incomplete skeleton

A tyrannosaurid, also present in the Dinosaur Park and Oldman Formations

Ornithomimus

O. tenuis

"Fragmentary metatarsal."[18]

A possible troodontid or juvenile tyrannosaurid

Paronychodon

P. lacustris

Teeth, type specimen

An indeterminate maniraptoran, also found in the Dinosaur Park, Milk River, Frenchman, Horseshoe Canyon, Scollard, and Lance and Kirtland Formations

Troodon

T. formosus

Teeth (type specimen), vertebra, egg

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

Zapsalis

Z. abradens

"Teeth,"[17] type specimen

Possible junior synonym of Paronychodon lacustris

Turtles

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

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

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

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". http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:007256. 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. ^ Sahni, A. (1972). "The vertebrate fauna of the Judith River Formation, Montana." Bulletin of the AMNH, v. 147 article 6: 321-415.
  6. ^ a b c Ryan and Evans, 2005
  7. ^ a b "Table 23.1," in Weishampel, et al. (2004). Page 495.
  8. ^ a b c d e f g h "Table 23.1," in Weishampel, et al. (2004). Page 496.
  9. ^ a b c d e "Table 20.1," in Weishampel, et al. (2004). Page 442.
  10. ^ 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 0253353580.
  11. ^ "Table 17.1," in Weishampel, et al. (2004). Page 368.
  12. ^ "Table 20.1," in Weishampel, et al. (2004). Page 443.
  13. ^ 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.
  14. ^ "Table 4.1," in Weishampel, et al. (2004). Page 78.
  15. ^ a b "Table 5.1," in Weishampel, et al. (2004). Page 114.
  16. ^ Fox, R.C. (1974). "A middle Campanian, nonmarine occurrence of the Cretaceous toothed bird Hesperornis Marsh." Canadian Journal of Earth Sciences, 11: 1335-1338.
  17. ^ a b c "Table 9.1," in Weishampel, et al. (2004). Page 186.
  18. ^ "Table 6.1," in Weishampel, et al. (2004). Page 139.