About 52 million years ago, when the Arctic was warm and swampy but still shrouded in six months of darkness during the polar winter, two small primates scampered around, using their strong jaw muscles to chew the vegetation hard to survive in the gloomy North. pole, a new study finds.
The two newfound primates – belonging to the already established primate genus Ignatiusand the names of the new species were given I. people and I. mckennai — they were small, weighing an estimated 5 pounds each (2 kilograms). They are the earliest known example of primates living in the Arctic, according to a new study published Wednesday (January 25) in the journal PLOS One (opens in a new tab).
This finding is based on an analysis of fossil jaws and teeth found on Ellesmere Island in Northern Canada. North of Baffin Bay, the island is just south of the Arctic Ocean. It is as far north as you can get in Canada.
“If you think about their modern relatives, primates or flying lemurs, these are among the most warm-adapted and warm-weather of all mammals, so they would be about the last mammals which you would expect to see up there, north of it. the Arctic Circle,” study senior author Christopher Beard (opens in a new tab)vertebrate paleontologist at the University of Kansas, told Live Science.
Both species lived during the Eocene Epoch (56 million to 33.9 million years ago), a period of intense planetary warming. At the time, there were no ice caps at the poles, and Ellesmere Island would have had a warm and muggy climate similar to present-day Savannah, Georgia, according to the first author’s study. Kristen Miller (opens in a new tab)doctoral student in Beard’s lab at the University of Kansas.
Related: Why didn’t all primates evolve into humans?
Indeed, temperatures on Ellesmere Island was hospitable enough to host a diverse ecosystem of unlikely animals, including early tapir-like ungulates (opens in a new tab) and even crocodiles, snakes and salamanders (opens in a new tab)according to earlier paleontological discoveries.
Although Eocene arctic dwellers did not have to deal with extreme temperatures, life in the warm Arctic was not without its challenges. Because of the tilt Worldand back, the sun does not rise on the island for half the year. “It’s been six months winter darkness and six months of it summer daylight,” Miller said.
The main challenge for animals living this far north is lack of food. Under such conditions, vegetation is likely to be sparse during the long, dark winter, so the researchers hypothesize that Arctic animals are hibernating. Igneous a genus probably subsisted on hard-to-chew foods, such as seeds or tree bark. To make meals out of such difficult foods, the researchers found that, compared to their arctic primate relatives further south, their cheekbones protrude further from their skulls, meaning that their some jaw muscles as well.
“The mechanical result of moving these masticatory muscles forward is that you generate greater bite forces,” Beard said.
Adaptations for northern latitudes do not stop with the jaw. The animals were much larger than their southern relatives, too. “Five pounds doesn’t sound very big, but compared to the guys’ ancestors, it’s a giant,” said Beard. “The close relatives of these animals that we find in Wyoming are the size of chipmunks.”
Its relatively large size is expected. Overall, there is a general trend in ecology known as Bergmann’s rule which states that the farther the animals live from the equator, the larger they are. Size is a common adaptation to colder temperatures, and yes, for a type of animal typically found in the tropics, the climate of the modern Georgia coast would have been relatively cool, making large size necessary for heat loss. to minimize.
The warming of the Eocene allowed many species to shift their ranges northward, a human-caused trend that ecologists are now seeing among modern species. climate change. As the planet warms, more species are likely to colonize the Arctic, but as Ignatiusmany will not form a single colony, but may diversify into new species once there.
“Given a little time, species will evolve their own distinctive features that will enable them to adapt even better to the Arctic,” said Beard. “I think it’s a really dynamic picture of what’s going to happen in the Arctic in the future with anthropogenic warming.