The Arctic today is a hostile place for most primates. But a series of fossils found since the 1970s suggest that wasn’t always the case.

Dozens of fossilized teeth and jaw bones unearthed in northern Canada belonged to two species of early primates – or at least close relatives of primates – that lived in the Arctic around 52 million years ago , report researchers on January 25 to PLOS ONE. These remains are the first primate-like fossils ever discovered in the Arctic and tell the story of a marmot-sized animal that may have walked through the trees in a swamp that once existed above the Arctic Circle.

The Arctic was noticeably warmer at that time. But the creatures still had to adapt to extreme conditions such as long months of sunless winter. These challenges make the presence of primate-like creatures in the Arctic “incredibly surprising,” says co-author Chris Beard, a paleontologist at the University of Kansas at Lawrence. “No other primate or primate relative has ever been found this far north until now.”

Between freezing temperatures, limited plant growth and months of perpetual darkness, living in the modern Arctic is not easy. This is especially true for primates, which evolved from small tree-dwelling creatures that ate largely on fruit (SN: 05/06/13). To date, most primates – with the exception of humans and a few other outliers like the Japanese snow monkeys – tend to stick to tropical and subtropical forests, which are largely found around the equator.

But these forests were not always confined to their current location. During the early Eocene, which began about 56 million years ago, the planet underwent a period of intense warming that allowed forests and their warm residents to expand northward (SN: 03/11/15).

Scientists know about this early Arctic climate in part from decades of paleontological work on Ellesmere Island in northern Canada. These excavations revealed that the area was once dominated by swamps similar to those found in the southeastern United States today. This ancient, hot and humid arctic environment was home to a wide range of heat-loving animals, including giant tapirs and relatives of crocodiles.

An illustration of an early reddish-brown groundhog-sized primate clinging to the side of a tree.
An early groundhog-sized primate, Ignatius Dawsonwho lived during the Eocene developed special teeth and strong jaws to survive the ubiquitous winter darkness above the Arctic Circle.Kristen Miller/Biodiversity Institute/Univ. of Kansas (CC-BY 4.0)

For the new study, Beard and his colleagues examined dozens of tooth and jawbone fossils found in the area, concluding that they belong to two species, Ignatius McKenna and Ignatius Dawson. Both species belonged to a now extinct genus of small mammals that was widespread throughout North America during the Eocene. The arctic variants likely headed north as the planet warmed, taking advantage of new habitat opening up near the poles.

Scientists have long debated whether this lineage could be considered true primates or if they were simply close relatives. Either way, it’s still “really weird and unexpected” to find primates or their relatives in the area, says Mary Silcox, a vertebrate paleontologist at the University of Toronto Scarborough.

For one thing, Ellesmere Island was already north of the Arctic Circle 52 million years ago. So while conditions may have been warmer and wetter, the marsh was plunged into continuous darkness during the winter months.

new arrived Ignatius should have adapted to these conditions. Unlike their southern relatives, the Arctic Ignatius had exceptionally strong jaws and teeth suitable for eating hard foods, the researchers found. This may have helped these early primates feed on nuts and seeds during the winter, when fruit was not as readily available.

This research can shed light on how animals can adapt to live in extreme conditions. “Ellesmere Island is arguably the best deep-time analogue for a mild, ice-free Arctic,” says Jaelyn Eberle, a vertebrate paleontologist at the University of Colorado Boulder.

Studying how plants and animals adapted to this remarkable time in Arctic history, Beard says, could offer clues to future Arctic residents.

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