Judith River Formation

Troodon ( ; Troödon in older sources) is a controversial genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period (about 77 million years ago). It includes at least one species, Troodon formosus, known from Montana. Discovered in October 1855, T. formosus was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877.

Gorgosaurus ( ; ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (Campanian), between about 76.5 and 75 million years ago. Fossil remains have been found in the Canadian province of Alberta and the U.S. state of Montana. Paleontologists recognize only the type species, G. libratus, although other species have been erroneously referred to the genus.

Daspletosaurus ( ; meaning "frightful lizard") is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 77 and 74.4 million years ago, during the Late Cretaceous Period. The genus Daspletosaurus contains three named species. Fossils of the earlier type species, D. torosus, have been found in Alberta, while fossils of a later species, D. horneri, have been found in Montana and Alberta. D. wilsoni has been suggested as an intermediate species between D. torosus and D. horneri that evolved through anagenesis, though further research may be required to definitively support the th

Monoclonius (meaning "single sprout") is an extinct dubious genus of herbivorous ceratopsian dinosaur found in the Late Cretaceous layers of the Judith River Formation in Montana, United States, and the uppermost rock layers of the Dinosaur Park Formation in Alberta, Canada dated to between 75 and 74.6 million years ago.

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

Aublysodon (“backwards-flowing tooth") is a dubious genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago).

Ceratops (meaning ) 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.

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.

Brachylophosaurus ( or ) is a genus of hadrosaurid dinosaur that lived during the Late Cretaceous period of western North America. It was first named in 1953 by Charles Mortram Sternberg for a skull and skeleton he discovered in 1936 in the Oldman Formation of Alberta, Canada, for which he named the new taxon Brachylophosaurus canadensis. While this single specimen was the only known material of Brachylophosaurus for a long time, extensive discoveries in the Judith River Formation of Montana, USA have uncovered not only additional skulls and skeletons with extensive impressions of skin, but al

Deinodon (Greek for "terrible tooth") is a dubious genus of tyrannosaurid dinosaur containing a single species, Deinodon horridus, which 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 the former.

Paronychodon (meaning "beside claw tooth") is an extinct theropod dinosaur genus. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include "buckets" of teeth from many disparate times and places but no other remains, and should be considered a form taxon.

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. thumb|left|Life restoration 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.

Trachodon (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian-aged (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 hadrosaurid dinosaur, the material it is based on is composed of teeth from both hadrosaurids and ceratopsids (their teeth have a distinctive double root), and its describer, Joseph Leidy, came to recognize the difference and suggested limiting the

Lokiceratops (meaning "Loki horned face") is an extinct genus of centrosaurine ceratopsian dinosaurs from the Late Cretaceous (Campanian) Judith River Formation of Montana, United States. The genus contains a single species, L. rangiformis, known from most of the skull and a partial skeleton. Four other ceratopsians are known from the same stratigraphic interval as Lokiceratops—more than in any other locality—suggesting that this clade was very diverse during the Late Cretaceous of northern Laramidia.

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.

Mercuriceratops is an extinct genus of herbivorous chasmosaurine ceratopsid dinosaur known from the Late Cretaceous (Campanian stage) of Alberta, Canada and Montana, United States. It contains a single species, Mercuriceratops gemini.

Dysganus (dis-GANN-us) (meaning "rough enamel") is a dubious genus of ceratopsian dinosaur from the Campanian stage of the Late Cretaceous. The fossil teeth referred to Dysganus were first collected by Charles Sternberg from the Judith River Formation of Montana and later described by Edward Drinker Cope. All of the species are now seen as dubious ceratopsians, though referred material from tyrannosaurids and hadrosaurids were found in New Mexico.

Palaeoscincus (meaning "ancient lizard" from and ) 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 t

Judiceratops ( ; meaning "Judith River horned face") is an extinct horned dinosaur. It lived around 78 million years ago, during the Late Cretaceous Period in what is now Montana, United States. Like other horned dinosaurs, Judiceratops was a large, quadrupedal herbivore. It is the oldest known chasmosaurine.

Cionodon (meaning 'column tooth') is a dubious genus of hadrosaurid dinosaur from the Late Cretaceous. The type species, C. arctatus, was found in the Denver Formation of Lodge Pole Creek, Colorado and was formally described by Edward Drinker Cope in 1874 based on the holotype AMNH 3951, collected in 1873. It is a nomen dubium because it is based on very fragmentary remains. Two other species have since been described: Cionodon kysylkumensis (Riabinin, 1931), based on the holotype CCMGE 1/3760 (a set of vertebrae) from Uzbekistan, and Cionodon stenopsis (Cope, 1875), discovered in rocks from t

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.

Probrachylophosaurus is a genus of large herbivorous brachylophosaurin hadrosaurid dinosaur known from the Late Cretaceous (Campanian) Judith River Formation of Montana and the Foremost Formation of Alberta. The type (and only named) species is Probrachylophosaurus bergei. First discovered in Montana in 1981 and not fully excavated until 2008, it was initially suspected to be a new species of Brachylophosaurus. However, in 2015 it was named as a distinct genus, with its name reflecting a suspected ancestral relationship. Both an adult and subadult specimen are known, and fragmentary remains wo

Zapsalis is a genus of dromaeosaurine theropod dinosaurs. It is a tooth taxon, often considered dubious because of the fragmentary nature of the fossils, which include teeth but no other remains.

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.

Furcatoceratops (meaning "forked horned face") is a genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous Judith River Formation of Montana. The type species is Furcatoceratops elucidans.

Pteropelyx (meaning "winged pelvis") 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, making the type species, P. grallipes, the only valid species. 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 Cor