The Ancient Grazer of the Colville River

Guest post by Evan Millsap, from University of Alaska, Fairbanks, Museum of the North, as part of our America’s Most Endangered Rivers® series spotlighting the Colville River.

Let’s open with a statement: The Colville River is Alaska’s greatest paleontological treasure. Exposures along the bluffs of the Colville River contain some of the most abundant and diverse fossil assemblages in the world. For over 20 years, paleontologists have been coming to the Colville in search of new species in an attempt to gain insight into life in the ancient Arctic. The sediment near the top of the bluffs are full of bones from extinct species of mammoths, whales, and walruses; but the underlying Prince Creek Formation contains fossils that are even more exciting: Alaskan dinosaurs.

Over fourteen new species of dinosaur have been discovered in the North Slope alongside three new species of dinosaur-era mammals. Every summer, as researchers come back to the Colville, they find more and more fossils that were previously overlooked. Most interestingly, these species are significantly different from dinosaurs found in other places. Some paleontologists now refer to the Colville area as a unique “biogeographic province,” with extinct animals unlike anywhere else in the world.

The North Slope in the age of the dinosaurs truly was remarkable. Due to the movement of Earth’s tectonic plates, it was even further north than it is today, and although the world generally was somewhat warmer, the Slope was still the coldest place in the world where dinosaurs lived (that we know of). The Alaskan dinosaurs in this area would have had to put up with 120 days of pure darkness, snow, and temperatures well below freezing. Paleontologists and geologists are still unraveling the puzzle, trying to figure out how they managed to survive in these conditions, what they ate, and how they stayed warm.

Alaska is a tough environment to do research in, and little paleontology is done here compared to other states. However, of the Alaskan dinosaurs that have been officially named, all of them come from the North Slope. Nanuqsaurus hoglandi was a ferocious, cold-hearty, meat eater and a distant cousin to T. Rex. Pachyrhinosaurus perotorum was a tough, brutish, herbivore with a giant boss, or frill, radiating out from its forehead.

Ugrunaaluk kuukpikensis, the famous dinosaur with a mouth like a duck-bill, has perhaps been studied and debated more than any other Alaskan dinosaur. For years, arguments centered around Ugrunaaluk’s winter habits, as many paleontologists believed these animals could not have survived the harsh climate and must have migrated vast distances just as modern caribou do. However, new detailed analyses of Ugrunaaluk’s bones reveal that this animal probably slowed growth during the winter and did not migrate very far, if at all. Ugrunaaluk must have been a common sight, as this species was an abundant, year-round resident. Ugrunaaluk fossils often weather out of the bluffs along the river and are found scattered along the beaches. More bones of this animal have been excavated than any other Alaskan species. It is truly the iconic Alaskan dinosaur, and is mounted proudly on display at the University of Alaska Museum of the North beneath a painting of the ancient North Slope and an aurora-lit sky.

It seems all too appropriate, then, that the iconic dinosaur of Alaska is named after the beautiful Colville, one of Alaska’s greatest rivers: in Iñupiat Ugrunaaluk kuukpikensis means “ancient grazer of the Colville River.”

Evan Millsap is a PH.D. student at University of Alaska, Fairbanks