Judith River Formation Explained

The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Montana Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago,^[4] 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^[5] and the Oldman Formation of Alberta.^[6] 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.^[3] 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.^[3] 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.^[7] The McClelland Ferry Member (78.7-76.3 Ma) is believed to be equivalent to the Oldman Formation, with the Coal Ridge Member (76.3-75.3 Ma) equivalent to the Dinosaur Park Formation.

Fauna

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

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
Nezpercius[9]	N. dodsoni	Clambank Hollow			A frog known from a partial illium.
Opisthotriton	O. kayi				A possible lungless salamander
Prodesmodon	P. copei				A lungless salamander
Scapherpeton	S. tectum				A scapherpetonid salamander

Fish

Bony fish

Bony fishes of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Arotus	A. hieroglyphus				A holostean.[10]
Belonostomus	Belonostomus longirostris				An aspidorhynchiform.
Cyclurus	C. fragosus				A bowfin.[11]
Lepisosteus	L. occidentalis			Scales[12]	A gar.
?Paralbula	?P. sp.				A bonefish.
Priscosturion	P. longipinnis	McClelland Ferry[13]	Upper Campanian		A sturgeon.
Psammorhynchus	P. longipinnis	McClelland Ferry	Upper Campanian		Preoccupied name, renamed Priscosturion.[14]
Polyodontidae	Indeterminate				A paddlefish. Known remains exceeded size of Chinese paddlefish, total length would exceed 2m (07feet).[15]

Cartilaginous fish

Cartilaginous fishes of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Myledaphus	M. bipartitus				A stingray.
Cretalamna	C. sp	Montana			An Otodontid shark
Carcharias	Carcharias sp.				A sand tiger shark
Squalicorax	S.kaupi				An Anacoracid shark

Pterosaurs

Pterosaurs of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
?Quetzalcoatlus[17]		Hidden Valley Quarry
Pterosauria	indet	JDM Quarry	McClelland Ferry[18]

Crocodilians

Crocodilians of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Brachychampsa	B. montana				An alligatorid.
Leidyosuchus	L. canadensis				An alligatoroid.
Deinosuchus	D. hatcheri[19]			Two giant dorsal vertebrae and a number of osteoderms.	An enormous alligatoroid.

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.

Ornithischians

Ankylosaurs

Ankylosaurs reported from the Judith River Formation
Genus	Species	Location	Member	Material	Notes	Images
Edmontonia	E. longiceps			Isolated teeth[20]	A nodosaurid.
Zuul	Z. crurivastator		middle Coal Ridge	Cranial and postcranial skeletal remains and soft tissue, type specimen	An ankylosaurid.

Hadrosaurs

Hadrosaurs reported from the Judith River Formation
Genus	Species	Location	Member	Material	Notes	Images
Brachylophosaurus	B. canadensis		middle McClelland Ferry		A hadrosaurid which was one of the more common dinosaurs in the area.[21]
Corythosaurus	C. sp.[22]		middle Coal Ridge	two partial skeletons	A lambeosaurine hadrosaurid
Probrachylophosaurus	P. bergei		lower McClelland Ferry		A brachylophosaurin hadrosaur

Marginocephalians

Ceratopsians

Ceratopsians reported from the Judith River Formation
Genus	Species	Location	Member	Material	Notes	Images
Albertaceratops	A. nesmoi[23]				Reclassified as Medusaceratops lokii
Avaceratops	A. lammersi[24]		lower McClelland Ferry	"[Two] partial skulls, skeleton, juvenile,"[25] type specimen	A ceratopsid. Possibly dubious.
Chasmosaurinae	gen. et sp. nov.			A mostly complete skull	MOR 11940, An unnamed Chasmosaur housed at the Museum of the Rockies.
Furcatoceratops	F. elucidans	Fergus County, Montana[26]	Upper Coal Ridge	Nearly complete subadult skeleton.	A ceratopsid
Judiceratops[27]	J. tigris		lower McClelland Ferry		A ceratopsid
Lokiceratops	L. rangiformis[28]	Kennedy Coulee	lower McClelland Ferry	Disarticulated, associated skeleton including most of the skull and fragmentary postcrania	A ceratopsid
Medusaceratops	M. lokii[29]		lower McClelland Ferry	Bonebed	A ceratopsid
Mercuriceratops	M. gemini[30]		lower Coal Ridge	"one apomorphic squamosal"	A ceratopsid
Spiclypeus	S. shipporum		McClelland Ferry[31]	Partial skull, vertebrae, ribs, humerus, ilium, femur, tibia, and fibula.	A ceratopsid

Pachycephalosaurs

Pachycephalosaurs reported from the Judith River Formation
Genus	Species	Location	Member	Material	Notes	Images
Colepiocephale	C. lambei[32]	Kennedy Coulee	lower McClelland Ferry	"nearly complete frontoparietal dome"	A pachycephalosaurid closely related to Stegoceras.
Hanssuesia	H. sternbergi				A pachycephalosaurid. Also present in the Dinosaur Park and Oldman Formations. Possible synonym of Stegoceras.

Theropods

Dromaeosaurs

Dromeosaurs reported from the Judith River Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Dromaeosaurus	D. albertensis	Ox Hill Quarry, Careless Creek Quarry, Hidden Valley Quarry & Blackbird Ridge Quarry.[33]	lower McClelland Ferry	Teeth	A dromaeosaurid, also found in the Dinosaur Park Formation
Saurornitholestes	S. langstoni	Careless Creek, Emily's Ankle, Top Cat, Hidden Valley & Blackbird Ridge quarries.	Lower McClelland Ferry	Numerous teeth	A dromaeosaurid

Tyrannosaurs

Tyrannosaurs reported from the Judith River Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Daspletosaurus	D. torosus		Coal Ridge	Maxilla[34]	A large tyrannosaurid.
	D. wilsoni[35]	Jack's B2	lower Coal Ridge[36]	Partial skull, cervical, sacral, and caudal vertebrae, and a rib, chevron, and first metatarsal	Originally considered to be a transitional species between D. torosus and D. horneri, though the validity of this claim has been questioned [37] [38] [39]
	D. sp.		Coal Ridge[40]	Partial skeleton[41] [42]	While initially referred to D. torosus [43] [44], it is more recently classified as Daspletosaurus sp. as it contains some characters in common with other named species of the genus as well as its own unique features. Furthermore, most of the skull is not preserved and is therefore missing many crucial features required for a specific classification [45]
Gorgosaurus	G. libratus			Postorbital	A large tyrannosaurid, also found in the Dinosaur Park Formation and possibly the Two Medicine Formation.
?Tyrannosaurus	T. sp.	Fergus County		A Lacrimal	Found alongside a specimen of Deinosuchus,[46] but may not be from the Judith River Formation[47]

Other theropods

Theropods reported from the Judith River Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Hesperornis	H. altus			Partial tibiotarsus	One of the only known freshwater occurrences of a hesperornithid.[48]
Ornithomimosauria indet.[49]	Indeterminate		Coal Ridge Member	A left and right dentary	A large ornithomimosaur with potential affinities to the Deinocheiridae
Richardoestesia	R. gilmorei	Careless Creek, Emily's Ankle, Hidden Valley & Blackbird Ridge quarries.		12 teeth	A coelurosaur

Dubious Taxa

Many early American dinosaur discoveries were made in the Judith River Formation, and most of the early taxa are considered nomina dubia today.

Turtles of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Aublysodon	A. lateralis			"Isolated teeth,"[50] [51] type specimen	Junior synonym of Deinodon horridus
	A. mirandus			Teeth, type specimen	Possible junior synonym of Deinodon horridus
Ceratops	C. montanus			"occipital condyle, paired horn cores,"[52] type specimen	A dubious ceratopsid
Deinodon	D. falculus			Teeth	Isolated tyrannosaur teeth classified in the dubious genus Deinodon
D. hazenianus			Teeth	Junior synonym of Deinodon horridus
D. horridus			"Teeth," type specimen	Isolated tyrannosaur teeth that formed the basis of the dubious genus Deinodon
D. incrassatus			Teeth	Junior synonym of Deinodon horridus
D. lateralis				Junior synonym of Deinodon horridus
Diclonius	D. calamarius			"Teeth."[53]	Nomen dubium
	D. pentagonius			"Fragmentary dentary with teeth," type specimen	A dubious hadrosaurid
	D. perengulatus			"Teeth."	Nomen dubium
Dromaeosaurus	D. explanatus			"Tooth."[54]	Possible relative of Saurornitholestes
	D. laevifrons			"Tooth."	Possible relative of Saurornitholestes
Dysganus	D. bicarinatus			"Isolated teeth."	Nomen dubium
	D. encaustus			"Single tooth and [five] tooth fragments." "Isolated teeth."	Nomen dubium
	D. haydenianus			"Isolated teeth."	Nomen dubium
	D. peiganus			"Tooth."	Nomen dubium
Hadrosaurus	H. paucidens				A dubious hadrosaur, sometimes known as Lambeosaurus paucidens
?"Kritosaurus"	?"K." breviceps				A dubious hadrosaurid
Monoclonius	M. crassus[55]		lower Coal Ridge	"[Five] skulls, [one] complete." Type specimen	A dubious ceratopsid
Ornithomimus	O. tenuis			"Fragmentary metatarsal."[56]	A possible troodontid or juvenile tyrannosaurid
Paleoscincus	P. costatus			"Tooth," type specimen	A dubious ankylosaur
Paronychodon	P. lacustris			Teeth, type specimen	An indeterminate maniraptoran, also found in the Dinosaur Park, Milk River, and Kirtland Formations
Pteropelyx	P. grallipes			"Skeleton lacking skull."[57]	A dubious hadrosaurid
Trachodon	T. mirabilis			Isolated teeth, type specimen	A dubious hadrosaurid
Troodon	T. formosus	Antelope Head, Careless Creek, Emily's Ankle, Top Cat & Hidden Valley quarries.		Teeth (type specimen), egg	A troodontid, possibly dubious. A neotype from the Two Medicine Formation has been proposed.
Zapsalis[58]	Z. abradens			"Teeth," type specimen	A dromaeosaurid

Turtles

Turtles of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Adocus[59]	A. sp.
Aspideretoides	A. sp
Aspideretoides	A. foveatus
Axestemys	A. spledidus
Basilemys	B. sp.				A Mesoamerican river turtle.
Boremys	B. sp
Boremys	B. pulchra
Chelydridae	indet.
Neuankylus	N. sp.
Neuankylus	N. eximius
Plesiobaena	P. antiqua

Flora

All the flora stated below is pulled from the PBDB.^{[60] [61] [62] [63]}

Ferns

Ferns of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Azollopsis	A. coccoides	Montana
Azolla	A. simplex	Montana
Biretisporites	B. deltoideus	Montana
Baculatisporites	B. sp	Montana
Cyathidites	C. sp	Montana
Deltoidospora	D. diaphana	Montana
Echinatisporis	E. sp	Montana
Laevigatosporites	L. haardtii	Montana
Todisporites	T. dubius	Montana

Gymnosperms

Conifers

Ferns of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Araucariales	Indeterminate	Montana
Pityosporites	P. constrictus	Montana
Taxodiaceaepollenites	T. hiatus	Montana

Angiosperms

Ferns of the Judith River Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Scabrastephanocolpites	S. lepidus	Montana
Monosulcites	M. riparius	Montana
Tubulifloridites	T. aedicula	Montana
Erdtmanipollis	E. procumbentiformis	Montana
Liliacidites	L. sp.	Montana

See also

• List of dinosaur-bearing rock formations

Notes and References

1. Hayden, F.V., 1871. Geology of the Missouri Valley: Preliminary report (4th annual) of the Geol. Surv. of Wyoming and portions of contiguous territories.
2. 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
3. Web site: Judith River Formation. Lexicon of Canadian Geologic Units. 2009-02-06.
4. Ramezani . Jahandar . Beveridge . Tegan L. . Rogers . Raymond R. . Eberth . David A. . Roberts . Eric M. . 2022-09-26 . Calibrating the zenith of dinosaur diversity in the Campanian of the Western Interior Basin by CA-ID-TIMS U–Pb geochronology . Scientific Reports . 12 . 1 . 16026 . 10.1038/s41598-022-19896-w . 2045-2322 . 9512893 . 36163377.
5. 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.
6. Book: Eberth, David A. . 1997 . Judith River Wedge . Currie, Philip J. . Phil Currie . Padian Kevin. Encyclopedia of Dinosaurs . limited . Academic Press . San Diego . 379–380 . 0-12-226810-5.
7. 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. 10.1086/684289. 2016JG....124...99R . 130555911. 0022-1376.
8. Sahni, A. (1972). "The vertebrate fauna of the Judith River Formation, Montana." Bulletin of the AMNH, v. 147 article 6: 321-415.
9. Web site: Nezpercius Blob, Carrano, Rogers, Forster et Espinoza, 2001 . Martín . C. . Sanchiz . B. . 2014 . Lisanfos KMS . 1.2 . Museo Nacional de Ciencias Naturales, MNCN-CSIC, Madrid (Spain) . 20 February 2014 . https://web.archive.org/web/20140224115111/http://www.lisanfos.mncn.csic.es/?module=taxon&id=1055&lang=en . 24 February 2014 .
10. Gardner . James D. . Brinkman . Donald B. . Murray . Alison M. . 2025-06-01 . Reidentification of the holotype of ‘Ceratodus’ hieroglyphus Cope from the Upper Cretaceous (Campanian) of Montana, USA, as the scale of a holostean fish . Palaeobiodiversity and Palaeoenvironments . en . 105 . 2 . 545–572 . 10.1007/s12549-025-00663-4 . 1867-1608.
11. Grande . Lance . Bemis . William E. . 1998-04-10 . A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History . Journal of Vertebrate Paleontology . en . 18 . sup1 . 1–696 . 10.1080/02724634.1998.10011114 . 0272-4634. subscription .
12. Leidy . J. . 1856-12-31 . Notice of remains of extinct reptiles and fishes, discovered by Dr. FV Hayden in the Bad Lands of the Judith River, Nebraska Territory. . Proceedings of the Academy of Natural Sciences of Philadelphia . 8 . 72–73 . 10.5281/zenodo.1038128.
13. Grande . Lance . Hilton . Eric J. . July 2006 . An Exquisitely Preserved Skeleton Representing a Primitive Sturgeon from the Upper Cretaceous Judith River Formation of Montana (Acipenseriformes: Acipenseridae: N. Gen. and Sp.) . Journal of Paleontology . en . 80 . S65 . 1–39 . 10.1666/05032.1 . 131689748 . 0022-3360. subscription .
14. Grande . Lance . Hilton . Eric J. . March 2009 . A replacement name for †Psammorhynchus Grande & Hilton, 2006 (Actinopterygii, Acipenseriformes, Acipenseridae) . Journal of Paleontology . en . 83 . 2 . 317–318 . 10.1666/08-137.1 . 85233540 . 0022-3360. subscription .
15. Grande . Lance . Bemis . William E. . 1991 . Osteology and Phylogenetic Relationships of Fossil and Recent Paddlefishes (Polyodontidae) with Comments on the Interrelationships of Acipenseriformes . Memoir (Society of Vertebrate Paleontology) . 1 . ii–121 . 10.2307/3889328 . 1062-161X. subscription .
16. Web site: Cow Creek (Cretaceous to of the United States) . PBDB.org.
17. Fiorillo . Anthony R. . January 1989 . The Vertebrate Fauna from the Judith River Formation (Late Cretaceous) of Wheatland and Golden Valley Counties, Montana . The Mosasaur . 4 . 127-142 .
18. Prieto-Marquez . Albert . 2005-03-11 . https://doi.org/10.1671/0272-4634(2005)025[0144:NIOTCO2.0.CO;2 New information on the cranium of Brachylophosaurus canadensis (Dinosauria, Hadrosauridae), with a revision of its phylogenetic position ]. Journal of Vertebrate Paleontology . 25 . 1 . 144–156 . 10.1671/0272-4634(2005)025[0144:NIOTCO]2.0.CO;2 . 0272-4634.
19. Book: Schwimmer, David. King of the Crocodylians: The Paleobiology of Deinosuchus. Indiana University Press. 2002. Bloomington, IN. 200.
20. Sahni . Ashok . 1972 . The vertebrate fauna of the Judith River Formation, Montana . Bulletin of the AMNH . 147 . 6 . 2246/1099 . en-US.
21. Book: Trexler . David . Murphy . Nate . Thompson . Mark . Carpenter . Kenneth . Horns and Beaks . June 2007 . Indiana University Press . Bloomington, IN . 117–133 . "Leonardo," a Mummified Brachylophosaurus (Ornithischia: Hadrosauridae) from the Judith River Formation of Montana.
22. Takasaki . Ryuji . Chiba . Kentaro . Fiorillo . Anthony R. . Brink . Kirstin S. . Evans . David C. . Fanti . Federico . Saneyoshi . Mototaka . Maltese . Anthony . Ishigaki . Shinobu . 2022-10-23 . Description of the first definitive Corythosaurus (Dinosauria, Hadrosauridae) specimens from the Judith River Formation in Montana, USA and their paleobiogeographical significance . The Anatomical Record . 306 . 7 . 1918–1938 . 10.1002/ar.25097 . 36273398 . 253081338 . 1932-8486.
23. Ryan and Evans, 2005
24. Ryan and Evans, 2005
25. "Table 23.1," in Weishampel, et al. (2004). Page 495.
26. Ishikawa . Hiroki . Tsuihiji . Takanobu . Manabe . Makoto . 2023-07-20 . Furcatoceratops elucidans, a new centrosaurine (Ornithischia: Ceratopsidae) from the upper Campanian Judith River Formation, Montana, USA. . Cretaceous Research . 151 . en . 105660 . 10.1016/j.cretres.2023.105660 . 260046917 . 0195-6671. subscription .
27. 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 . 10.3374/014.054.0103 . 129801786 .
28. Loewen . Mark A. . Sertich . Joseph J. W. . Sampson . Scott . Scott D. Sampson . O'Connor . Jingmai K. . Jingmai O'Connor . Carpenter . Savhannah . Sisson . Brock . Øhlenschlæger . Anna . Farke . Andrew A. . Makovicky . Peter J. . Longrich . Nick . Evans . David C. . David C. Evans (paleontologist) . 2024-06-20 . Lokiceratops rangiformis gen. et sp. nov. (Ceratopsidae: Centrosaurinae) from the Campanian Judith River Formation of Montana reveals rapid regional radiations and extreme endemism within centrosaurine dinosaurs . . en . 12 . e17224 . 10.7717/peerj.17224 . free . 2167-8359 . 11193970 .
29. 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. .
30. 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
31. 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 . 2017PLoSO..1288426F . 10.1371/journal.pone.0188426 . 1932-6203 . 5699823 . 29166406 . free.
32. Schott . Ryan K. . Evans . David C. . Williamson . Thomas E. . Carr . Thomas D. . Goodwin . Mark B. . 2009-09-12 . The anatomy and systematics of Colepiocephale lambei (Dinosauria: Pachycephalosauridae) . Journal of Vertebrate Paleontology . en . 29 . 3 . 771–786 . 10.1671/039.029.0329 . 0272-4634.
33. Fiorillo . Anthony R. . Currie . Philip J. . 1994-03-31 . Theropod teeth from the Judith River Formation (Upper Cretaceous) of south-central Montana . Journal of Vertebrate Paleontology . en . 14 . 1 . 74–80 . 10.1080/02724634.1994.10011539 . 0272-4634.
34. 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. Journal of Vertebrate Paleontology. 38. Supplement 1. 102.
35. Warshaw . Elías A.. Fowler . Denver W. . 2022 . A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana . . 10 . e14461 . 10.7717/peerj.14461 . 36452080 . 9703990 . free.
36. Warshaw . Elías A. . Guevara . Daniela Barrera . Fowler . Denver W. . November 2024 . Anagenesis and the tyrant pedigree: A response to "Re-analysis of a dataset refutes claims of anagenesis within Tyrannosaurus-line tyrannosaurines (Theropoda, Tyrannosauridae)" . Cretaceous Research . 163 . 105957 . 10.1016/j.cretres.2024.105957 . 0195-6671. free .
37. Scherer . Charlie Roger . Voiculescu-Holvad . Christian . November 28, 2023 . Re-analysis of a dataset refutes claims of anagenesis within Tyrannosaurus-line tyrannosaurines (Theropoda, Tyrannosauridae) . . In press . 105780 . 10.1016/j.cretres.2023.105780 . 0195-6671. free .
38. Warner-Cowgill . E. . Storrs . G. W. . Rogers . R. R. . Maltese . A. E. . Cranial anatomy and stratigraphy of a new specimen of the tyrannosaurine dinosaur Daspletosaurus from the Judith River Formation of Central Montana, USA . 2025 . Acta Palaeontologica Polonica . 70 . 1 . 159–174 . 10.4202/app.01143.2024 . free .
39. Voris . Jared T. . Zelenitsky . Darla K. . Darla Zelenitsky . Kobayashi . Yoshitsugu . Yoshitsugu Kobayashi . Modesto . Sean P. . Therrien . François . Tsutsumi . Hiroki . Chinzorig . Tsogtbaatar . Tsogtbaatar . Khishigjav . June 11, 2025 . A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria . . 642 . 8069 . 973–979 . 10.1038/s41586-025-08964-6 . 40500434 . 2025Natur.642..973V . en . 0028-0836.
40. Maltese, Anthony E. "DIFFICULT EXCAVATION AND PREPARATION OF A LARGE DASPLETOSAURUS SPECIMEN." Methods in Preparation: 63.
41. Maltese, Anthony E. "DIFFICULT EXCAVATION AND PREPARATION OF A LARGE DASPLETOSAURUS SPECIMEN." Methods in Preparation: 63.
42. Warner-Cowgill . E. . Storrs . G. W. . Rogers . R. R. . Maltese . A. E. . Cranial anatomy and stratigraphy of a new specimen of the tyrannosaurine dinosaur Daspletosaurus from the Judith River Formation of Central Montana, USA . 2025 . Acta Palaeontologica Polonica . 70 . 1 . 159–174 . 10.4202/app.01143.2024 . free .
43. Maltese, Anthony E. "DIFFICULT EXCAVATION AND PREPARATION OF A LARGE DASPLETOSAURUS SPECIMEN." Methods in Preparation: 63.
44. Scherer . Charlie Roger . Voiculescu-Holvad . Christian . November 28, 2023 . Re-analysis of a dataset refutes claims of anagenesis within Tyrannosaurus-line tyrannosaurines (Theropoda, Tyrannosauridae) . . In press . 105780 . 10.1016/j.cretres.2023.105780 . 0195-6671. free .
45. Warner-Cowgill . E. . Storrs . G. W. . Rogers . R. R. . Maltese . A. E. . Cranial anatomy and stratigraphy of a new specimen of the tyrannosaurine dinosaur Daspletosaurus from the Judith River Formation of Central Montana, USA . 2025 . Acta Palaeontologica Polonica . 70 . 1 . 159–174 . 10.4202/app.01143.2024 . free .
46. Urban . Michael A. . Lamanna . Matthew C. . December 2006 . Evidence of a Giant Tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous (?Campanian) of Montana . Annals of Carnegie Museum . en . 75 . 4 . 231–235 . 10.2992/0097-4463(2006)75[231:EOAGTD]2.0.CO;2 . 0097-4463. subscription .
47. Dalman . Sebastian G. . Lucas . Spencer G. . Malinzak . D. Edward . 2018 . Tyrannosaurid teeth from the upper Cretaceous (Campanian) Two Medicine Formation of Montana . New Mexico Museum of Natural History and Science Bulletin . 79 . 125–139.
48. Fox, R.C. (1974). "A middle Campanian, nonmarine occurrence of the Cretaceous toothed bird Hesperornis Marsh." Canadian Journal of Earth Sciences, 11: 1335-1338.
49. Chinzorig. Tsogtbaatar. Takasaki. Ryuji. Chiba. Kentaro. Fiorillo. Anthony R.. Kobayashi. Yoshitsugu. Saneyoshi. Mototaka. Ishigaki. Shinobu. 2025-09-10. A potential deinocheirid ornithomimosaur from the Judith River Formation (Upper Cretaceous: Montana, U.S.A.) and its paleobiogeographic implications. Journal of Vertebrate Paleontology. en. e2536844. (13 pages). 10.1080/02724634.2025.2536844.
50. "Table 4.1," in Weishampel, et al. (2004). Page 78.
51. "Table 5.1," in Weishampel, et al. (2004). Page 114.
52. "Table 23.1," in Weishampel, et al. (2004). Page 496.
53. "Table 20.1," in Weishampel, et al. (2004). Page 442.
54. "Table 9.1," in Weishampel, et al. (2004). Page 186.
55. Ryan and Evans, 2005
56. "Table 6.1," in Weishampel, et al. (2004). Page 139.
57. "Table 20.1," in Weishampel, et al. (2004). Page 443.
58. 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
59. Smith . Heather F. . Berg . Madison . Adrian . Brent . 2023 . A well-preserved cranium from the Judith River Formation (Montana, USA) reveals the inner ear and neuroanatomy of a Campanian baenid turtle . The Anatomical Record . en . 306 . 6 . 1431–1451 . 10.1002/ar.25185 . 1932-8494.
60. Web site: JWHall #223, Phillips Co., MT (Cretaceous to of the United States) . PBDB.org.
61. Web site: Leo Site, Malta (Cretaceous of the United States) . PBDB.org.
62. Web site: West end of the Fort Peck reservoir at the Robinson Bridge (Cretaceous to of the United States) . PBDB.org.
63. Web site: Loki Quarry, Kennedy Coulee (Cretaceous of the United States) . PBDB.org.