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Two of the oldest known primate-like mammals came from the Arctic

The mammals lived about 52 million years ago.

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Artist's reconstruction of Ignacius dawsonae surviving six months of winter darkness in the extinct warm temperate ecosystem of Ellesmere Island, Arctic Canada (Photo by Kristen Miller, Biodiversity Institute, University of Kansas via SWNS)

By Mark Waghorn via SWNS

Two of the oldest known primate-like mammals came from the Arctic, reveals new research.

They were dug up on Canada's Ellesmere island, off the northwest coast of Greenland - and lived about 52 million years ago.

An asteroid strike that wiped out non-avian dinosaurs 14 million years earlier spurred the evolution of smaller animals.

These included Ignacius dawsonae and Ignacius mckennai - close relatives of early primates.

Lead author Kristen Miller, a doctoral student at Kansas University, said: "They descended from a common northbound ancestor who possessed a spirit to boldly go where no primate has gone before."

About the size of a squirrel, they were identified from fossilized fragments of jaws and teeth.

The pair's remains date back to a period known geologically as the Eocene - a time of intense global warming.

It provides a crucial case study for examining how ecosystems react to changing climates - with implications today.

The animals gorged on nuts and seeds as they adapted to the swamps and jungles of prehistoric Canada - and half the year spent in darkness.

Lead author Kristen Miller, a graduate student at the University of Kansas, said: "Global warming is transforming Arctic ecosystems in ways that are difficult to predict.

"But ancient episodes of global warming show how future changes in the Arctic might unfold."

The primate relatives described in PLOS ONE are the first ever reported from the ancient ecosystem.

Miller said: "No primate relative has ever been found at such extreme latitudes. They're usually found around the equator in tropical regions.

"I was able to do a phylogenetic analysis, which helped me understand how the fossils from Ellesmere Island are related to species found in midlatitudes of North America - places like New Mexico, Colorado, Wyoming and Montana.

"Even down in Texas, we have some fossils that belong to this family as well."

The Arctic Circle was much warmer when these close evolutionary cousins of primates lived — a boreal ecosystem that hosted a plethora of early vertebrates, including ancient crocodiles.

But like today, it was still mostly dark for half of the year. This darkness may have triggered both species to evolve more robust teeth and jaws compared with other primate relatives of the time.

Miller explained: "A lot of what we do in paleontology is look at teeth - they preserve the best."

She analyzed high-resolution computer scans.

Miller said: "Their teeth are just super weird compared to their closest relatives.

"So, what I've been doing the past couple of years is trying to understand what they were eating, and if they were eating different materials than their middle-latitude counterparts."

Miller and her co-authors believe food was much tougher to find during dim winter months when the Artic primate relatives likely were forced to consume harder material.

Corresponding author Professor Chris Beard said: "That, we think, is probably the biggest physical challenge of the ancient environment for these animals.

"How do you make it through six months of winter darkness, even if it's reasonably warm? The teeth and even the jaw muscles of these animals changed compared to their close relatives from midlatitudes.

"To survive those long Arctic winters, when preferred foods like fruits were not available, they had to rely on 'fallback foods' like nuts and seeds."

Both species were slightly larger than their closest relatives farther to the south — a group of primate cousins dubbed plesiadapiforms.

Arctic landscape in Svalbard
An arctic landscape. (Greens and Blues via Shutterstock)

Miller said: "But they're still pretty small. Some plesiadapiforms from the midlatitudes of North America are really, really tiny.

"Of course, none of these species are related to squirrels, but I think that's the closest critter that we have that helps us visualise what they might have been like. They were most likely very arboreal — so, living in the trees most of the time."

The researchers think adaptations displayed by both Arctic species during a time of global warming show how some animals likely could evolve new traits in response to climate change driven by human activity today.

Miller said: "It does show how something like a primate or a primate relative that’s specialized to one environment can change based off of climate change.

"I think probably what it says is primates' range could expand with climate change or move at least towards the poles rather than the equator.

"Life starts to get too hot there, perhaps we'll have a lot of taxa moving north and south, rather than the intense biodiversity we see at the equator today."

Compared to similar species from more southern localities, the animals had distinctive physical characteristics suited to their unusual environment.

Being relatively large is a common trait in modern northern mammals. They also had dental features that suggest a diet of hard food items.

This would have enabled feeding on tough conifers, oaks, pecans and other trees during long, dark winters where softer meals were hard to come by.

During the Eocene, the lower latitudes of North America were home to many early primate relatives.

But only these two species are known by this Arctic community.

It adds to previous evidence that this ecosystem experienced limited biodiversity compared to more southern habitats.

The researchers say warming climates allowed certain organisms to migrate northward, but such movement might be limited by factors such as long periods of Arctic darkness.

Such insights are crucial for predictions about how ecosystems might react to modern warming climates.

Miller added: "The first primate-like fossils ever recovered north of Arctic Circle show that these tropically adapted mammals were able to colonize the Arctic during an ancient episode of global warming approximately 52 million years ago by adopting a new diet of nuts and seeds that enabled them to survive six months of winter darkness."

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