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Fossils suggest early primates lived in a once-swampy Arctic

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, researchers report January 25 in PLOS ONE. These remains are the first primate-like fossils ever discovered in the Arctic and tell of a groundhog-sized animal that may have skittered across trees in a swamp that once existed above the Arctic Circle.  

The Arctic was significantly warmer during that time. But creatures still had to adapt to extreme conditions such as long winter months without sunlight. These challenges make the presence of primate-like creatures in the Arctic “incredibly surprising,” says coauthor Chris Beard, a paleontologist at the University of Kansas in Lawrence. “No other primate or primate relative has ever been found this far north so far.”

Between frigid temperatures, limited plant growth and months of perpetual darkness, living in the modern Arctic isn’t easy. This is especially true for primates, which evolved from small, tree-dwelling creatures that largely fed on fruit (SN: 6/5/13). To this day, most primates — humans and few other outliers like Japan’s snow monkeys excepted — tend to stick to tropical and subtropical forests, largely found around the equator.

But these forests haven’t always been confined to their present location. During the early Eocene Epoch, which started around 56 million years ago, the planet underwent a period of intense warming that allowed forests and their warm-loving residents to expand northward (SN: 11/3/15).

Scientists know about this early Arctic climate in part because of decades of paleontological work on Ellesmere Island in northern Canada. These digs revealed that the area was once dominated by swamps not unlike those found in the southeastern United States today. This ancient, warm, wet Arctic environment was home to a wide array of heat-loving animals, including giant tapirs and crocodile relatives.

An illustration of a reddish-brown, groundhog-sized early primate clinging to the side of a tree.
A groundhog-sized early primate, Ignacius dawsonae, that lived during the Eocene evolved special teeth and strong jaws to survive the pervasive 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 teeth and jawbone fossils found in the area, concluding that they belong to two species, Ignacius mckennai and Ignacius dawsonae. These two species belonged to a now-extinct genus of small mammals that was widespread across North America during the Eocene. The Arctic variants probably made their way north as the planet warmed, taking advantage of the new habitat opening up near the poles.

Scientists have long debated whether this lineage can be considered true primates or whether they were simply close relatives. Regardless, 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 swamp was plunged into continuous darkness during the winter months.

Newly arrived Ignacius would have had to adapt to these conditions. Unlike their southern kin, the Arctic Ignacius had unusually strong jaws and teeth suited to eating hard foods, the researchers found. This may have helped these early primates feed on nuts and seeds over the winter, when fruit wasn’t 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 analog 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 period in Arctic history, Beard says, could offer clues to the Arctic’s future residents.

Source link Palaeontologists have discovered the remains of several small primates in the northern reaches of Ellesmere Island in Canada’s Nunavut province in what is believed to be the furthest north any early primate has been found.

The fossils date back to approximately 55 million years ago and are evidence of an unknown early primate species. Even more astonishing is that at this time the area was a sprawling freshwater swamp with an abundance of vegetation and warmth at the same latitude that is now a cold, treeless tundra.

According to a paper written by the international team of researchers, the new discovery sets a benchmark for establishing the earliest occurrence of primates in the Arctic regions. The authors also point out that without knowing more about the fossil primate and its environment during the Eocene period, it is difficult to make deductions about the animal’s behaviour and adaptations from its fossils.

The fossilised remains were found within the deposits of a shallow lake that existed thousands of years ago. Even after so much time the researchers were able to determine details of the climate and life forms that existed in the Arctic around 55 million years ago. In addition to the primates, the fossils of trees, reptiles, invertebrates and other animals were discovered.

The discovery indicates that primate evolution may be more dynamic and widespread than previously thought, with some primates continuing to evolve in an Arctic environment over millions of years even while they were adapting to other climates elsewhere.

It is too early to say whether the new primate species could eventually be considered ancestral to modern primates. How the little creature spread from the Arctic to other parts of the world 55 million years ago remains unknown. It does however offer new insight into the dynamic nature of primate evolution and suggests a possible range for early primate migration.

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