The Dinosaurs and Prehistoric Animals of Alaska

Albertosaurus, a dinosaur native to Alaska.

 Royal Tyrrell Museum

Given its position between North America and Eurasia, Alaska has had a complicated geologic history. For much of the Paleozoic and Mesozoic Eras, significant parts of this state were underwater, and its climate was lusher and more humid than it is today, making it an ideal home for dinosaurs and marine reptiles; this warming trend reversed itself during the subsequent Cenozoic Era, when Alaska became home to a large population of thickly pelted megafauna mammals. On the following slides, you'll discover the most important dinosaurs and prehistoric animals ever to have lived in Alaska.

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Wikimedia Commons/FunkMonk

In September 2015, researchers in Alaska announced the discovery of a new genus of hadrosaur, or duck-billed dinosaur: Ugrunaaluk kuukpikensis, indigenous for "ancient grazer." Surprisingly, this plant-eater lived in the northern fringes of the state during the late Cretaceous period, about 70 million years ago, meaning that it managed to survive in relatively frigid conditions (about 40 degrees Fahrenheit during the day, a truly freezing temperature for your average duckbill).

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Eduardo Camarga

One of the newest pachycephalosaurs (bone-headed dinosaurs) on the prehistoric block, Alaskacephale was named in 2006 after, you guessed it, the state in the U.S. where its incomplete skeleton was discovered. Originally believed to be a species (or perhaps a juvenile) of the better-known Pachycephalosaurus, the 500-pound, head-butting Alaskacephale was later reinterpreted as deserving its own genus based on slight variations in its skeletal structure. 

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Royal Tyrrell Museum

As you can guess from its name, Albertosaurus honors Canada's Alberta province, where most of the fossils of this Tyrannosaurus Rex-sized tyrannosaur have been discovered, dating to the late Cretaceous period. However, some intriguingly "albertosaurine" remains have also been unearthed in Alaska, which may turn out to belong either to Albertosaurus itself or to another closely related genus of tyrannosaur, Gorgosaurus.

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Dmitry Bogdanov

One hundred and fifty million years ago, during the late Jurassic period, a large portion of the North American continent — including parts of Alaska — was submerged beneath the shallow Sundance Sea. Although most fossil specimens of the giant marine reptile Megalneusaurus have been unearthed in Wisconsin, researchers have discovered smaller bones in Alaska, which may wind up being assigned to juveniles of this 40-foot-long, 30-ton behemoth. 

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Karen Carr

Pachyrhinosaurus, the "thick-nosed lizard," was a classic ceratopsian, the family of horned, frilled dinosaurs that roamed North America (including parts of Alaska) during the late Cretaceous period. Oddly enough, unlike most other ceratopsians, the two horns of Pachyrhinosaurus were set on top of its frill, not on its snout. In 2013, an incomplete nasal bone fossil specimen discovered in Alaska was assigned as a separate Pachyrhinosaurus species, P. perotorum.

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Wikimedia Commons

Like Albertosaurus, Edmontosaurus was named after a region in Canada — not the city of Edmonton, but the "Edmonton formation" of lower Alberta. And, also like Albertosaurus, the fossils of some very Edmontosaurus-like dinosaurs have been unearthed in Alaska — meaning that this hadrosaur (duck-billed dinosaur) may have had a wider geographic range than previously believed, and was able to withstand the near-freezing temperatures of late Cretaceous Alaska.

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Thescelosaurus dinosaur, white background.

Getty Images/Nobumichi Tamura/Stocktrek Images

The most controversial dinosaur on this list, Thescelosaurus was a small (only 600 pounds or so) ornithopod, scattered fossils of which have been discovered in Alaska. What makes Thescelosaurus such a prehistoric hot potato is the claim of some researchers that a "mummified" specimen from South Dakota bears the fossilized evidence of internal organs, including a four-chambered heart; not everyone in the paleontology community agrees.

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The Woolly Mammoth

woolly mammoth
Wikimedia Commons

The official state fossil of Alaska, the Woolly Mammoth was thick on the ground during the late Pleistocene epoch, its dense, shaggy coat allowing it to thrive in conditions inhospitable to all but the most well-equipped megafauna mammals. In fact, the discovery of frozen carcasses in the northernmost reaches of Alaska (as well as neighboring Siberia) has fueled hopes of someday "de-extincting" Mammuthus primigenius by inserting its DNA fragments into a modern elephant genome.

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Various Megafauna Mammals

Mammoth walking in nature by day.

Getty Images/​Elena Duvernay/Stocktrek Images

Somewhat surprisingly, except for the Woolly Mammoth, not much is known about the megafauna mammals of late Pleistocene Alaska. However, a trove of fossils discovered in (of all places) Lost Chicken Creek helps to redress the balance somewhat: no prehistoric chickens, sadly, but rather bison, horses, and caribou. It does appear, however, that these mammals were existing species of their still-living counterparts, rather than completely extinct genera.

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Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Alaska." ThoughtCo, Sep. 3, 2021, Strauss, Bob. (2021, September 3). The Dinosaurs and Prehistoric Animals of Alaska. Retrieved from Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Alaska." ThoughtCo. (accessed June 3, 2023).