Judith River Formation

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.

Judith River Formation
Stratigraphic range: Campanian, 79–74.9 Ma
Leonardo mummified brachylophosaurus
"Leonardo," a rare intact mummified Brachylophosaurus canadensis uncovered in the Judith River Formation.
TypeGeological formation
Unit ofJudith River Group
Sub-unitsBirch Lake Member, Ribstone Creek Member, Brosseau Member, Victoria Member
UnderliesBearpaw Formation
OverliesClaggett Formation, Pakowki Formation
Thicknessmax 360 meters (1,180 ft)[2]
PrimarySiltstone and sandstone
OtherCoal, coquinas
Coordinates47°40′N 109°39′W / 47.667°N 109.650°WCoordinates: 47°40′N 109°39′W / 47.667°N 109.650°W
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 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.


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.


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
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.


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


H. dilatus

A siren.


L. bairdi

A scapherpetonid salamander.


O. kayi

A possible lungless salamander.


P. copei

A lungless salamander.


S. tectum

A scapherpetonid salamander.

Bony fish

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


Belonostomus longirostris

An aspidorhynchiform.


K. fragosa

A bowfin.


L. occidentalis

A gar.


?P. sp.

A bonefish.

Cartilaginous fish

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


M. bipartitus

A stingray.

Ornithischian dinosaurs




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


C. segnis

A whiptail.


E. lancensis

A knob-scaled lizard.


L. denticulatus

A whiptail.


P. bogerti

A parasaniwid.


P. wyomingensis

A parasaniwid.

Theropod dinosaurs

An unnamed tyrannosaurine is known from the formation.[17]


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


B. sp.

A Mesoamerican river turtle.

See also


  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. ^ 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. ^ Schwimmer, David (2002). King of the Crocodylians: The Paleobiology of Deinosuchus. 601 North Morton Street, Bloomington, IN: Indiana University Press. p. 200.
  17. ^ 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.
  18. ^ "Table 4.1," in Weishampel, et al. (2004). Page 78.
  19. ^ a b "Table 5.1," in Weishampel, et al. (2004). Page 114.
  20. ^ Fox, R.C. (1974). "A middle Campanian, nonmarine occurrence of the Cretaceous toothed bird Hesperornis Marsh." Canadian Journal of Earth Sciences, 11: 1335-1338.
  21. ^ a b c "Table 9.1," in Weishampel, et al. (2004). Page 186.
  22. ^ "Table 6.1," in Weishampel, et al. (2004). Page 139.
  23. ^ 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
1856 in paleontology

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1856.


Albertaceratops (meaning "Alberta horned face") was a genus of centrosaurine horned dinosaur from the middle Campanian-age Upper Cretaceous Oldman Formation of Alberta, Canada.


Avaceratops is a genus of small herbivorous ceratopsian dinosaurs which lived during the late Campanian during the Late Cretaceous Period in what are now the Northwest United States. Most fossils come from the Judith River Formation.


Brachylophosaurus ( brə-KIL-ə-fo-SAWR-əs or brak-i-LOH-fə-SAWR-əs; meaning "short-crested lizard", Greek brachys = short + lophos = crest + sauros = lizard, referring to its small crest) was a mid-sized member of the hadrosaurid family of dinosaurs. It is known from several skeletons and bonebed material from the Judith River Formation of Montana and the Oldman Formation of Alberta, living about 78 million years ago.


Ceratops (meaning "horn face") is a dubious genus of herbivorous ceratopsian dinosaur which lived during the Late Cretaceous. Its fossils have been found in the Judith River Formation in Montana. Although poorly known, Ceratops is important in the history of dinosaurs, since it is the type genus for which both the Ceratopsia and the Ceratopsidae have been named. The material is too poor to be confidently referred to better specimens, and Ceratops is thus considered a nomen dubium.


Deinodon (Greek for "terrible tooth") is a dubious tyrannosaurid dinosaur genus containing a single species, Deinodon horridus. D. horridus is known only from a set of teeth found in the Late Cretaceous Judith River Formation of Montana and named by paleontologist Joseph Leidy in 1856. These were the first tyrannosaurid remains to be described and had been collected by Ferdinand Vandeveer Hayden. The teeth of Deinodon were slightly heterodont, and the holotype of Aublysodon can probably be assigned to Deinodon.


Diclonius (meaning "double sprout") is a genus of dinosaur from the Late Cretaceous. It was a hadrosaur based solely on teeth. Its fossils were found in the Judith River Formation of Montana, northern US. The name is in reference to the method of tooth replacement, in which newly erupting replacement teeth could be in functional use at the same time as older, more worn teeth. Thus, the number of "sprouting" teeth was doubled in comparison to Monoclonius ("single sprout"), which used only one set of teeth at a time and which Cope named in the same paper.The type species, Diclonius pentagonus, was named by Edward Drinker Cope in 1876, based on a single tooth specimen (AMNH 3972). Other formally undescribed species include D. calamarius and D. perangulatus. Although Cope referred several other batches of teeth to the genus, under several species, the name is considered a nomen dubium.


Dysganus (dis-GANN-us) (meaning "rough enamel") is a dubious genus of ceratopsian dinosaur from the Campanian stage of the Late Cretaceous. Its fossil teeth were discovered by Edward Drinker Cope in the Judith River Formation in Montana.


Eodelphis (ee-o-DEL-fiss), from eo- plus [Di]delphis, thus meaning "very early opossum", is a genus of stagodont metatherians from the Late Cretaceous of North America, with distinctive crushing dentition. Named species include E. browni and the more advanced E. cutleri. Both come from the Late Campanian (Judithian "Land Mammal Age") of Dinosaur Provincial Park, Alberta. Specimens are also known from the Judith River Formation of Montana. E. cutleri is related to the Maastrichtian genus Didelphodon as indicated by its enlarged premolars and more robust jaw. Eodelphis was probably an aquatic predator like its relative Didelphodon, and may have weighed about 0.6 kg (1.3 lb), making it one of the largest mammals of its time.


Hanssuesia is a genus of pachycephalosaurid dinosaurs from the late Cretaceous period. It lived in what is now Alberta and Montana, and contains the single species Hanssuesia sternbergi.

Hanssuesia is based on a skull dome originally named Troodon sternbergi by Barnum Brown and Erich Maren Schlaikjer in 1943. The specific name honoured Charles Mortram Sternberg who found the dome in 1928 near Steveville in south Alberta. In 1945, it was transferred to Stegoceras by C.M. Sternberg himself, as a Stegoceras sternbergi.The genus Hanssuesia was first named by Robert M. Sullivan in 2003. It honours paleontologist Hans-Dieter Sues. In the publication also the spelling variant "Hanssuessia" appeared; the same year Sullivan chose for Hanssuesia as the valid name. Its type species is Troodon sternbergi, the combinatio nova is Hanssuesia sternbergi.

H. sternbergi is known from the holotype NMC 8817 and six referred specimens (mainly frontoparietals) which were collected from two formations of the Belly River Group of Alberta, Canada, the Dinosaur Park Formation (late Campanian, 76.5–75 ma) in the Dinosaur Provincial Park, and the Oldman Formation (middle Campanian, 77.5-76.5 ma), as well as from the upper Judith River Formation of Montana, United States (late Campanian, 76–75 ma).Like other pachycephalosaurs, Hanssuesia had a thick skull roof. However, Hanssuesia is distinguished from other pachycephalosaurs by having a depressed parietal region, a frontoparietal dome that is wide in front as well as in the rear, a broad nasal boss on the frontals, reduced but swollen prefrontal lobes, and a reduced parietosquamosal shelf at the dome rear.

Judith River Group

The Judith River Group is a group of geologic formations in western North America dating from the late Cretaceous and noted as a site for the extensive excavation of dinosaur fossils. The formation is named after the Judith River in Montana. The group is also called the Judith River Wedge. It is stratigraphically equivalent with the Belly River Group in Alberta.It comprises the Judith River Formation in north central Montana, as well as the Foremost, Oldman, and Dinosaur Park formations in Alberta and Saskatchewan in Canada. Within Canada, the name term Belly River Group is more widely used for what is essentially the same stratigraphic interval as the Judith River. The wedge is exposed discontinuously in river drainages.

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 on the river banks, located in section 15-11-54-3W4M by J.A. Allan in 1918. The early campanian age was determined from its foraminifera and mollusks found in the formation.


Medusaceratops is an extinct genus of centrosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation (middle Campanian stage) of Montana, northern United States. It contains a single species, Medusaceratops lokii.


Palaeoscincus (meaning "ancient skink" from the Greek παλαιός and σκίγγος) is a dubious genus of ankylosaurian dinosaur based on teeth from the mid-late Campanian-age Upper Cretaceous Judith River Formation of Montana. Like several other dinosaur genera named by Joseph Leidy (Deinodon, Thespesius, and Trachodon), it is an historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists. Because of its wide use in the early 20th century, it was somewhat well known to the general public, often through illustrations of an animal with the armor of Edmontonia and the tail club of an ankylosaurid.


Probrachylophosaurus bergei is a species of large herbivorous brachylophosaurin hadrosaurid dinosaur known from the Late Cretaceous Campanian Judith River Formation, of Montana.

The significance of this particular hadrosaur taxon is that it is a transitional species between the genera Acristavus and Brachylophosaurus evolving from a crestless ancestor (the former genus) to its crested descendant (the latter genus) while changing the morphology of its nasal bones.


Pteropelyx is a dubious genus of Late Cretaceous hadrosaurid dinosaur from the Judith River Formation of Montana, named by Edward Drinker Cope in 1889. Historically, several species were assigned to it, all based on extremely fragmentary remains, but there is no evidence to support these assignments. Most of these other species' remains likely belong to better-known hadrosaurs, such as Lambeosaurus and Gryposaurus. It is probable that the type material of Pteropelyx, a skeleton lacking a skull, is from Corythosaurus (making Pteropelyx its senior synonym) (Brett-Surman, 1989), but the lack of a skull makes such a synonymy impossible to determine with sure certainty as no certain evidence pertain to prove the organ to be present.


Spiclypeus (meaning "spike shield") is an extinct genus of chasmosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation (late Campanian stage) of Montana, United States.


Trachodon (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-age Upper Cretaceous Judith River Formation of Montana, U.S. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists.Despite being used for decades as the iconic duckbill dinosaur per antonomasia the material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double root), and its describer, Joseph Leidy, came to recognize the difference and suggested limiting the genus to what would now be seen as ceratopsid teeth. Restricted to the duckbill teeth, it may have been a lambeosaurine.


Zuul is a genus of herbivorous ankylosaurine dinosaur from the Campanian Judith River Formation of Montana. The type species is Zuul crurivastator. It is known from a complete skull and tail, which represents the first ankylosaurin known from a complete skull and tail club, as well as the most complete ankylosaurid specimen thus far recovered from North America. The specimen also preserved in situ osteoderms, keratin, and skin remains.

Hydrocarbon history
Depositional regions
Central Alberta


This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.