Early relative of primate ancestor lived in Canadian Arctic | Polarjournal
Aside from living in trees, there is nothing in Ignacius dawsonae to suggest that a related species would evolve into the ancestors of primates, and thus us. But this and the sister species Ignacius mckennai are among the Primatomorpha, ancestors of primates, and are about 52 million years old. Image: Kristen Miller, Kansas University

If one asks nowadays when and where human evolution took place, it is relatively quickly referred to Africa and, depending on the species, to 7 to 8 million years. But these early ancestors were themselves the result of an evolution that goes back much further, especially out of Africa. That’s because researchers have now described fossils about it that were found far in the Canadian Arctic nearly 50 years ago.

The analysis of fossil teeth show that 52 million years ago on the island of Ellesmere had lived two species of animals that belonged to the group of those animals from which later emerged the primates, and eventually we. Those are the findings of a study by University of Kansas doctoral student Kristen Miller, her supervisor Professor Chris Beard, and illustrator Kristen Tietjen, which have now appeared in the journal PLOS One. Since the two species had previously been unknown, the research team was able to determine the names and agreed on Ignacius dawsonae and Ignacius mckennai, in honor of paleontologists Dr. Mary Dawson and Dr. Malcolm McKenna, both of whom had conducted their research on Ellesmere Island.

Kristen Miller, along with her supervisor Chris Beard, examined fossil teeth that had been discovered by paleontologist Dr Mary Dawson during excavations on Ellesmere Island back in the 1970s. To do this, the researchers used micro-CT scanners and compared the teeth with already known species. “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,” Kristen Miller explains. It turned out that the teeth found point in the direction of the so-called Primatomorpha, ancestors of primates. “But their teeth are just super weird compared to their closest relatives.,” Miller continues. That’s why the doctoral student studied not only the teeth themselves, but also assumed the food options in the region under the conditions that prevailed at the time.

Data from the site show that the animals had lived in the region about 52 million years ago, a time when it was much warmer than today, but provides picture of what the Arctic is likely to look like as warming continues. The region had a much higher diversity, a boreal, swampy landscape very much dominated by months of polar night darkness. This affected the development of the two species. Analysis of the teeth shows that the ancestors of both species had migrated from the midwestern United States and had grown larger on Ellesmere than their southern relatives. “Their ancestor must have possessed some kind of pioneering spirit, boldly going where no primate had gone before,” says Kristen Miller. But they were still pretty small, probably like big squirrels, Miller says. They were also tree dwellers, feeding on fruits, nuts and seeds. Especially the latter must have constituted an important part of the diet, as the wear of the teeth showed.

Now, the results do not mean that the Arctic was the cradle of humanity. But to the researchers, they are an indication of how species had responded to a changing climate back then and a parallel to today. “I think primates’ range could expand with climate change or move at least towards the poles rather than the equator,” Kristen Miller says. “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.”

Dr Michael Wenger, PolarJournal

Link to the study: Miller et al. (2023) PLOS One 18(1) Basal Primatomorpha colonized Ellesmere Island (Arctic Canada) during the hyperthermal conditions of the early Eocene climatic optimum; doi.org/10.1371/journal.pone.0280114

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