A restoration of Ugrunaaluk in its Arctic home.
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Art by James Havens.
A restoration of Ugrunaaluk in its Arctic home.

The Arctic’s “Edmontosaurus” Gets a New Name

Dinosaurs lived all over the world during their Mesozoic heyday. Maps in books and documentaries drove the point home to me during my childhood dinomania, dots scattered across the globe showing all the places where the great reptiles had been found. But, no doubt influenced by Fantasia and the “monkey puzzles and parking lots” style of paleo art, I envisioned all those little specks as steaming swamps or lush floodplains in an endless dinosaurian summer. The thought of dinosaurs striding through the snow didn’t occur to me at all.

Bones excavated from Alaska’s extension into the Arctic Circle have changed that. Fossils from the 71-68 million year old stone of the Price Creek Formation have revealed a dinosaurian fauna that lived year-round in a place where it occasionally got cold enough to snow. The image of tyrannosaurs, horned dinosaurs, and hadrosaurs walking through the cool forests of ancient Alaska has run so counter to the classic Mesozoic imagery that it’s not surprising that this environment has been the subject of several recent documentaries and even a feature film. But in each cinematic reprise, the cast of dinosaurs keeps changing.

Dinosaurs don’t usually come down to us as complete or even articulated skeletons. Jumbles of bones, piles of fragments, and isolated teeth are far more common. These are usually enough to narrow down the type of dinosaur present, and from there paleontologists sometimes turn to more completely-known dinosaurs from the same time, but different places, as hypothetical stand-ins for the more fragmentary species. In the southwestern United States, for example, tyrannosaur bones from New Mexico were categorized as those of the northern Daspletosaurus before paleontologists realized they represented a hitherto unknown genus subsequently rechristened Bistahieversor.

The same sort of recategorization has been going on with Alaska’s dinosaurs. Early last year, for example, paleontologist Anthony Fiorillo and Ronald Tykoski announced that tyrannosaur bones previously called “Gorgosaurus” really belonged to a dwarfed tyrant they named Ronald Tykoski announced that tyrannosaur bones previously called “Gorgosaurus” really belonged to a dwarfed tyrant they named Ronald Tykoski announced that tyrannosaur bones previously called “Gorgosaurus” really belonged to a dwarfed tyrant they named Nanuqsaurus. Now Hirotsugu Mori, Patrick Druckenmiller, and Gregory Erickson have recognized another new dinosaur hiding in the Arctic bone pile – a hadrosaur that had previously gone by the name “Edmontosaurus“.

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The reconstructed skull of Ugrunaaluk. From Mori et al., 2015.

Excavations since the 1990s have turned up numerous hadrosaur bones from the Price Creek Formation, and, given their age and anatomy, those remains have generally been categorized as those of Edmontosaurus – a famous hadrosaur found further south through Canada and the United States. But no one had made a strong case for this assignment. When Mori and colleagues went back to the fossils, they found that the Arctic hadrosaur differed in a variety of anatomical landmarks and bone shapes on the skull. In short, the Price Creek Formation hadrosaur was different enough to merit establishing it as a new dinosaur. The dinosaur is now Ugrunaaluk kuukpikensis – a title based on the Iñupiaq language meaning “ancient grazer of the Colville River”. And if you have a little trouble with the name, the authors included a little pronunciation guide. Say it “oo-GREW-nah-luk”.

Ugrunaaluk is far from the last new dinosaur hiding in the Alaskan Arctic. So far paleontologists have recognized 13 distinct dinosaurs from the Price Creek Formation, but Ugrunaaluk is only the fourth – along with Nanuqsaurus, Pachyrhinosaurus, and Alaskacephale – to be confidently identified down to species. For paleontologists, there’s still much to discover in the Arctic’s lost world.


Mori, H., Druckenmiller, P., Erickson, G. 2015. A new Arctic hadrosaurid from the Prince Creek Formation (lower Maastrichtian) of northern Alaska. Acta Palaeontologica Polonica. doi: 10.4202/app.00152.2015