The Dinosaurs and Prehistoric Animals of Utah

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Which Dinosaurs and Prehistoric Animals Lived in Utah?

Camarasaurus, a dinosaur of Utah. Dmitry Bogdanov

A huge number of dinosaurs and prehistoric animals have been discovered in Utah--so many that this state is virtually synonymous with the modern science of paleontology. What is Utah's big secret, compared to relatively dinosaur-poor states nearby, like Idaho and Nevada? Well, from the late Jurassic through the late Cretaceous periods, much of the Beehive State was high and dry, perfect conditions for the preservation of fossils over tens of millions of years. On the following slides, you'll discover the most famous dinosaurs and prehistoric animals discovered in Utah, ranging from Allosaurus to Utahceratops. (See a list of dinosaurs and prehistoric animals discovered in each U.S. state.)

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Allosaurus, a dinosaur of Utah. Wikimedia Commons

Although it's the official state fossil, the "type specimen" of Allosaurus wasn't actually discovered in Utah. However, it was the excavation of thousands of tangled Allosaurus bones from this state's Cleveland-Lloyd Quarry, in the early 1960's, that allowed paleontologists to conclusively describe and classify this late Jurassic dinosaur. No one is quite sure why all these Allosaurus individuals died at the same time; they may have gotten trapped in thick mud, or simply died of thirst while gathering around a dry watering hole.

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Utahraptor, a dinosaur of Utah. Wikimedia Commons

When most people talk about raptors, they tend to focus on late Cretaceous genera like Deinonychus or, especially, Velociraptor. But the biggest raptor of them all, the 1,500-pound Utahraptor, lived at least 50 million years before either of these dinosaurs, in early Cretaceous Utah. Why did raptors dwindle in size so drastically toward the end of the Mesozoic Era? Most likely, their ecological niche was displaced by bulkier tyrannosaurs, causing them to evolve toward the more petite end of the theropod spectrum.

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Utahceratops, a dinosaur of Utah. University of Utah

Ceratopsians--horned, frilled dinosaurs--were thick on the ground in Utah during the late Cretaceous period; among the genera that called this state home were Diabloceratops, Kosmoceratops and Torosaurus (which may actually have been a species of Triceratops). But the most representative ceratopsian discovered in the Beehive State is none other than Utahceratops, a 20-foot-long, four-ton behemoth that lived on an isolated island cut off from the rest of Utah by the Western Interior Sea.

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Seitaad, a dinosaur of Utah. Nobu Tamura

Among the first plant-eating dinosaurs on earth, prosauropods were the distant ancestors of the giant sauropods and titanosaurs of the later Mesozoic Era. Recently, paleontologists in Utah discovered the near-complete skeleton of one the earliest, smallest prosauropods in the fossil record, Seitaad, a tiny plant-muncher of the middle Jurassic period. Seitaad measured only 15 feet from head to tail and weighed as little as 200 pounds, a far cry from later Utah-dwelling behemoths like Apatosaurus.

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Various Sauropods

Brontomerus, a dinosaur of Utah. Getty Images

Utah is justly famous for its sauropods, which figured prominently in the late 19th century Bone Wars--he take-no-prisoners competition between the eminent American paleontologists Edward Drinker Cope and Othniel C. Marsh. Species of Apatosaurus, Barosaurus, Camarasaurus and Diplodocus have all been discovered in this state; a more recent find, Brontomerus (Greek for "thunder thighs"), possessed the thickest, most muscular  hind legs of any sauropod yet identified.

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Various Ornithopods

Eolambia, a dinosaur of Utah. Lukas Panzarin

Roughly speaking, ornithopods were the sheep and cattle of the Mesozoic Era: smallish, not-too-bright, plant-eating dinosaurs whose sole function (it sometimes seems) was to be mercilessly preyed on by ravenous raptors and tyrannosaurs. Utah's roster of ornithopods includes Eolambia, Dryosaurus, Camptosaurus and Othnielia (the last of these named after Othniel C. Marsh, who was extremely active in the American west in the late 19th century).

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Various Ankylosaurs

Animantarx, a dinosaur of Utah. Wikimedia Commons

Discovered in Utah in 1991, Cedarpelta was an extremely early ancestor of the giant ankylosaurs (armored dinosaurs) of late Cretaceous North America, including Ankylosaurus and Euoplocephalus. Other armored dinosaurs discovered in this state include Hoplitosaurus, Hylaeosaurus (only the third dinosaur in history ever to be named) and Animantarx. (This last dinosaur is especially interesting, as it type fossil was discovered with the aid of radiation-detecting equipment rather than a pick and shovel!)

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Various Therizinosaurs

Nothronychus, a dinosaur of Utah. Getty Images

Technically classified as theropod dinosaurs, therizinosaurs were a strange offshoot of this usually meat-eating breed that subsisted almost entirely on plants. The type fossil of Nothronychus, the first therizinosaur ever to be identified outside Eurasia, was discovered in Utah in 2001, and this state was also home to the similarly built Falcarius. The unusually long claws of these dinosaurs didn't disembowel living prey; rather, they were used to rope in vegetation from the high branches of trees.

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Various Late Triassic Reptiles

Drepanosaurus, a relative of which was recently discovered in Utah. Nobu Tamura

Until very recently, Utah was relatively lacking in fossils dating to the late Triassic period--the time when dinosaurs were only recently beginning to evolve from their archosaur ancestors. That all changed in October of 2015, when researchers discovered a "treasure trove" of late Triassic creatures, including two early theropod dinosaurs (which bear a close resemblance to Coelophysis), a few small, crocodile-like archosaurs, and a strange, tree-dwelling reptile closely related to Drepanosaurus.

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Various Megafauna Mammals

Megalonyx, a prehistoric mammal of Utah. Wikimedia Commons

Although Utah is best known for its dinosaurs, this state was home to a wide variety of megafauna mammals during the Cenozoic Era--and especially the Pleistocene epoch, from two million to 10,000 or so years ago. Paleontologists have unearthed the fossils of Smilodon (better known as the Saber-Toothed Tiger), the Dire Wolf and the Giant Short-Faced Bear, as well as a common denizen of late Pleistocene North America, Megalonyx, aka the Giant Ground Sloth.

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Your Citation
Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Utah." ThoughtCo, Feb. 16, 2021, Strauss, Bob. (2021, February 16). The Dinosaurs and Prehistoric Animals of Utah. Retrieved from Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Utah." ThoughtCo. (accessed March 24, 2023).