The Arctic may seem like an unlikely place for life to thrive today, but new fossils from northern Alaska tell a very different story. Researchers have identifiedthree previously unknown mammal species that lived there about 73 million years ago, revealing that the ancient polar region was a place where mammals adapted, diversified, and even moved between continents.
The discovery comes fromfossil teeth recovered in Alaska’s Prince Creek Formation, a site inside the Arctic Circle that has already produced a rich collection of dinosaur and mammal fossils. The newly identified species are adding another piece to the puzzle of what life looked like in the far north during the Late Cretaceous.
The findings, published in the Proceedings of the National Academy of Sciences (PNAS), also challenge the long-held idea that the prehistoric Arctic sat on the sidelines of mammal evolution.
Tiny Teeth Reveal Three New Species
The three newly described fossil species have been named Camurodon borealis, Qayaqgruk peregrinus, and Kaniqsiqcosmodon polaris. Scientists identified them from fossilized teeth that are around 73 million years old.
All three belonged to a group of extinct mammals called multituberculates. Roughly the size of modern mice or rats, they became one of the most successful mammal groups in Earth’s history, surviving for more than 100 million years. They even outlasted the asteroid impact that wiped out the non-avian dinosaurs. For comparison, Homo sapiens has been around for only about 300,000 years.
Life in Arctic Alaska was far from easy. Even then, the region experienced months of darkness during winter, freezing temperatures, and times when food was probably difficult to find. Still, these mammals managed to survive. Patrick Druckenmiller, a co-author of the study from the University of Alaska Fairbanks, said that:
“These three new mammal species add to a growing body of evidence that this ancient arctic region was home to unique, polar-adapted species.”
Different Diets Allowed Them to Share the Same Habitat
Although the animals were closely related, their teeth suggest they were not all eating the same things. The researchers found that Camurodon borealis was likely a herbivore. Qayaqgruk peregrinus appears to have eaten both plants and insects, while Kaniqsiqcosmodon polaris was also probably an omnivore, although plants seem to have made up most of its diet.
Those differences may have helped the species avoid competing for the same food at a time when resources could become scarce. Sarah Shelley, the study’s first author, said the diversity seen among multituberculates may also explain why the group lasted so long. She noted that:
“I think they can reveal a lot about the resilience of mammals, not just to the mass extinction, but also to climatic stresses that many organisms are facing today.”
A Much Earlier Journey Between Asia And North America
The study also uncovered evidence of an ancient migration. One of the newly identified species, Qayaqgruk peregrinus, is closely related to a mammal that lived in what is now Mongolia. Based on that relationship, the research team concluded that its ancestors moved from Asia into North America around 92 million years ago.
Jaelyn Eberle, the study’s senior author, said the fossil discovery shows that a land bridge connecting the two continents was already being used by small mammals about 90 million years ago. Shelley added that the finding also changes the way scientists think about native species, showing that animals have been moving across continents and reshaping ecosystems for hundreds of millions of years.
“It really challenges how we think about native species. Deep time reminds us that a place is not just a point on a map, but a long, layered history of landscapes and inhabitants,” she added.
