The Dinosaurs and Prehistoric Animals of Montana

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Which Dinosaurs and Prehistoric Animals Lived in Montana?

maiasaura — Maiasaura, a dinosaur of Montana. Wikimedia Commons

Thanks to this state's famous fossil beds--including the Two Medicine Formation and the Hell Creek Formation--a huge number of dinosaurs have been discovered in Montana, giving paleontologists a broad glimpse of prehistoric life during the Jurassic and Cretaceous periods. (Oddly enough, this state's fossil record is relatively scarce during the ensuing Cenozoic Era, consisting mostly of small plants rather than big animals). On the following slides, you'll learn about the most notable dinosaurs, pterosaurs and marine reptiles that once called Montana home. (See a list of dinosaurs and prehistoric animals discovered in each U.S. state.)

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Tyrannosaurs and Large Theropods

Not only has Montana yielded numerous specimens of Tyrannosaurus Rex--the most famous meat-eating dinosaur that ever lived--but this state was also home to Albertosaurus (at least when it wandered down from its usual haunts in Canada), Allosaurus, Troodon, Daspletosaurus, and the evocatively named Nanotyrannus, aka the "tiny tyrant." (There's some debate, however, about whether Nanotyrannus merits its own genus, or was actually a juvenile of the more famous T. Rex.)

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Raptors

deinonychus — Deinonychus, a dinosaur of Montana. Wikimedia Commons

The world's most famous raptor, Velociraptor, may have lived half a world away in Mongolia, but the genera discovered in Montana have pumped up this state in the world rankings. Late Cretaceous Montana was the hunting ground of both the big, scary Deinonychus (the model for the so-called "Velociraptors" in Jurassic Park) and the tiny, goofily named Bambiraptor; this state may also have been terrorized by Dakotaraptor, recently discovered in neighboring South Dakota.

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Ceratopsians

einiosaurus — Einiosaurus, a dinosaur of Montana. Sergey Krasovskiy

Late Cretaceous Montana was rife with herds of Triceratops--the most famous of all the ceratopsians (horned, frilled dinosaurs)--but this state was also the stomping ground of Einiosaurus, Avaceratops and the eponymous Montanoceratops, which was distinguished by the elongated spines along the top of its tail. More recently, paleontologists discovered the tiny skull of the rabbit-sized Aquilops, one of the first ceratopsians to colonize middle Cretaceous North America.

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Hadrosaurs

tenontosaurus — Tenontosaurus, a dinosaur of Montana. Perot Museum

Hadrosaurs--duck-billed dinosaurs--occupied a crucial ecological niche in late Cretaceous Montana, primarily as herding, slow-witted prey animals that attracted the attention of hungry tyrannosaurs and raptors. Among the most notable hadrosaurs of Montana were Anatotitan (aka the "giant duck," also known as Anatosaurus), Tenontosaurus, Edmontosaurus and Maiasaura, the fossilized hatchlings of which have been discovered by the hundreds at Montana's "Egg Mountain."

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Sauropods

diplodocus — Diplodocus, a dinosaur of Montana. Alain Beneteau

Sauropods--the huge, ponderous, trunk-legged plant-eaters of the late Jurassic period--were the biggest dinosaurs of the Mesozoic Era. The state of Montana was home to at least two famous members of this enormous breed, Apatosaurus (the dinosaur formerly known as Brontosaurus) and Diplodocus, one of the most common dinosaurs in natural history museums worldwide thanks to the charitable efforts of the American industrialist Andrew Carnegie.

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Pachycephalosaurs

stegoceras — Stegoceras, a dinosaur of Montana. Sergey Krasovskiy

Most states are lucky to produce even a single genus of pachycephalosaur ("thick-headed lizard"), but Montana was home to three: Pachycephalosaurus, Stegoceras and Stygimoloch. Recently, one famous paleontologist has claimed that some of these dinosaurs represent "growth stages" of existing genera, putting the pachycephalosaur playing field in a state of disarray. (Why did these dinosaurs have such big noggins? Most likely so the males could head-butt each other for dominance during mating season.)

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Ankylosaurs

Montana's late Cretaceous quarries have yielded three famous genera of ankylosaurs, or armored dinosaurs--Euoplocephalus, Edmontonia and (of course) the eponymous member of the breed, Ankylosaurus. As slow and dumb as they undoubtedly were, these heavily armored plant-eaters were well protected from the ravages of Montana's raptors and tyrannosaurs, which would have had to flip them onto their backs, and slash open their soft underbellies, in order to procure a tasty meal.

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Ornithomimids

struthiomimus — Struthiomimus, a dinosaur of Montana. Sergio Perez

Ornithomimids--"bird mimic" dinosaurs--were some of the fastest terrestrial animals that ever lived, some species capable of running at top speeds of 30, 40 or even 50 miles per hour. The most famous ornithomimids of Montana were Ornithomimus and the closely related Struthiomimus, though there's been some controversy about how different these two dinosaurs really were (in which case one genus may wind up being "synonymized" with the other).

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Pterosaurs

quetzalcoatlus — Quetzalcoatlus, a pterosaur of Montana. Nobu Tamura

As plentiful as dinosaur fossils are in Montana, the same can't be said for pterosaurs, vanishingly few of which have been discovered across the expanse of the Hell Creek Formation (which includes not only Montana, but also Wyoming and North and South Dakota). However, there is some tantalizing evidence for the existence of giant "azhdarchid" pterosaurs; these remains have yet to be classified, but they may wind up being assigned to the biggest pterosaur of them all, Quetzalcoatlus.

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Marine Reptiles

elasmosaurus — Elasmosaurus, a marine reptile of Montana. Wikimedia Commons

As is the case with pterosaurs (see previous slide), very few marine reptiles have been discovered in Montana, at least compared with now-landlocked states like Kansas (which was once covered by the Western Interior Sea). Montana's late Cretaceous fossil deposits have yielded the scattered remains of mosasaurs, the fast, vicious marine reptiles that lasted until the K/T Extinction 65 million years ago, but this state's single most famous marine reptile is the late Jurassic Elasmosaurus (one of the instigators of the notorious Bone Wars).

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Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Montana." ThoughtCo, Sep. 8, 2021, thoughtco.com/dinosaurs-and-prehistoric-animals-of-montana-1092084. Strauss, Bob. (2021, September 8). The Dinosaurs and Prehistoric Animals of Montana. Retrieved from https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-montana-1092084 Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Montana." ThoughtCo. https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-montana-1092084 (accessed May 30, 2023).