Two Medicine Formation

Styracosaurus ( ; meaning "spiked lizard" from the Ancient Greek / "spike at the butt-end of a spear-shaft" and / "lizard") is an extinct genus of herbivorous dinosaur from the Late Cretaceous (Campanian stage) of North America. It had four to six long parietal spikes extending from its neck frill, a smaller jugal horn on each of its cheeks, and a single horn protruding from its nose, which may have been up to long and wide. The function or functions of the horns and frills have been debated for many years.

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.

Maiasaura (from , and , the feminine form of saurus, ) is a large herbivorous saurolophine hadrosaurid ("duck-billed") dinosaur genus that lived in the area currently covered by the state of Montana and the Canadian province of Alberta, in the Upper Cretaceous (mid to late Campanian), from 86.3 to 70.6 million years ago. Maiasaura is the state fossil of Montana.

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

Bambiraptor is a genus of bird-like dromaeosaurid theropod dinosaur that lived during the Late Cretaceous (about 72 million years ago) of Montana. It was described by scientists at the University of Kansas, Yale University, and the University of New Orleans. The holotype fossil is less than long, although this specimen appears to be a juvenile, and it is possible that Bambiraptor is a juvenile Saurornitholestes. It is even suspected that the type specimen is a chimera, based on the fact that "there are elements of three different similarly sized lower legs included in the holotype." Because of

Achelousaurus () is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 77 to 74.8 million years ago. The first fossils of Achelousaurus were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to the Greek deity Achelous, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individu

Hypacrosaurus (meaning "near the highest lizard" [from Ancient Greek ὑπο- hypo- "less" and ἄκρος akros "high"], because it was almost but not quite as large as Tyrannosaurus) is an extinct genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75.0 to 69.5 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It was

Gryposaurus (meaning "hooked-nosed (Greek grypos) lizard"; sometimes incorrectly translated as "griffin (Latin gryphus) lizard") was a genus of duckbilled dinosaur that lived about 80 to 75 million years ago, in the Late Cretaceous (late Santonian to late Campanian stages) of North America. Named species of Gryposaurus are known from the Dinosaur Park Formation in Alberta, Canada, and two formations in the United States: the Lower Two Medicine Formation in Montana and the Kaiparowits Formation of Utah. A possible additional species from the Javelina Formation in Texas may extend the temporal r

Einiosaurus is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Upper Cretaceous (Campanian stage) of northwestern Montana. The name means 'bison lizard', in a combination of Blackfeet Indian eini and Latinized Ancient Greek sauros; the specific name (procurvicornis) means 'with a forward-curving horn' in Latin. Einiosaurus is medium-sized with an estimated body length at .

Prosaurolophus (; meaning "before Saurolophus", in comparison to the later dinosaur with a similar head crest) is a genus of hadrosaurid (or duck-billed) dinosaur from the Late Cretaceous of North America. It is known from the remains of at least 25 individuals, including skulls and skeletons, but this remains obscure. Its fossils have been found in the late Campanian-aged Dinosaur Park Formation in Alberta, and the roughly contemporaneous Two Medicine Formation in Montana, dating to around 75.7 to 74.1 million years ago. Its most recognizable feature is a small solid crest formed by the nasal

Saurornitholestes ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta and Saskatchewan) and the United States (Montana, New Mexico, Alabama, and South Carolina). Two species have been named that are regarded as valid: Saurornitholestes langstoni in 1978 and Saurornitholestes sullivani in 2015. Saurornitholestes was a small, bipedal, meat-eating dinosaur, equipped with a sickle-like claw on each foot.

thumb|Reconstruction of the Orodromeus skeleton

Prenoceratops, (meaning 'bent or prone-horned face' and derived from Greek prene-/πρηνη- meaning 'bent forwards' or 'prone', cerat-/κερατ- meaning 'horn' and -ops/ωψ meaning 'face') is a genus of herbivorous ceratopsian dinosaur from the Late Cretaceous Period. It was a relatively small dinosaur, reaching in length and in body mass. Its fossils have been found in the upper Two Medicine Formation in the present-day U.S. state of Montana, in Campanian age rock layers that have been dated to 74.3 million years ago. Fossils were also found in the Oldman Formation in the modern day Canadian provinc

Brachyceratops ('short horned face') is a dubious genus of ceratopsian dinosaur from the late Cretaceous Period of Montana, United States. Brachyceratops has historically been known from juvenile remains, with one specimen having since been re-classified as Rubeosaurus ovatus.

Cerasinops (meaning 'cherry face') was a small ceratopsian dinosaur. It lived during the Campanian of the late Cretaceous Period. Its fossils have been found in Two Medicine Formation, in Montana. The type species of the genus Cerasinops is C. hodgskissi.

Scolosaurus is an extinct genus of ankylosaurid dinosaurs within the subfamily Ankylosaurinae. It is known from the lower levels of the Dinosaur Park Formation and upper levels of the Oldman Formation in the Late Cretaceous (latest middle Campanian stage, about 76.5 Ma ago) of Alberta, Canada. The genus contains two species, S. cutleri and S. thronus. The type species, S. cutleri, measured up to in length and in body mass.

Stellasaurus (meaning "star lizard"; both in reference to the shape of its head ornamentation and as an homage to the song "Starman" by David Bowie) is a genus of centrosaurine ceratopsid dinosaur that lived in Montana during the Late Cretaceous. The type and only species is Stellasaurus ancellae. Its remains have been found in the late Campanian-aged Two Medicine Formation, the same geological unit which its relatives Rubeosaurus (now seen as a synonym of Styracosaurus), Einiosaurus, and Achelousaurus were discovered in.

Glishades (from the Latin "glis" meaning "mud", and the Greek "Hades", the mythological lord of the underworld; also meaning "unseen"; together meaning "concealed in mud", referring to being found in sedimentary strata while metaphorically referring to the world beneath the surface where fossils form) is a genus of hadrosauroid dinosaur that lived in the Late Cretaceous in North America. It is based on AMNH 27414, two partial premaxillae discovered in the Upper Cretaceous rocks of the upper Two Medicine Formation in Montana, dated to about 74.5 million years ago. Cladistic analysis conducted b

geological formation in North America

Oohkotokia ( ) is a genus of ankylosaurid dinosaur within the subfamily Ankylosaurinae. It is known from the upper levels of the Two Medicine Formation (late Campanian stage, about 74 Ma ago) of Montana, United States. The discovery of Oohkotokia supports that Ankylosaurine dinosaurs existed and flourished continuously in Montana and/or Alberta throughout the late Campanian and early Maastrichtian stages in the Late Cretaceous period. It was a large, heavily built, quadrupedal, herbivore, that could grow up to long and weigh up to .

Brontotholus () is an extinct genus of pachycephalosaurid dinosaur known from the Late Cretaceous (Campanian stage) Two Medicine and Oldman formations of Montana, United States, and Alberta, Canada, respectively. The genus contains a single species, Brontotholus harmoni, known from multiple partial domes.