This Ancient Species of Arctic Rhino May Have Crossed a Land Bridge 23 Million Years Ago
Rhinoceroses living across Canada may sound strange, but 23 million years ago, it was a reality. Researchers from the Canadian Museum of Nature (CMN) have recently discovered the remains of a now extinct rhinoceros species that lived in Canada’s High Arctic.
According to a new study published in Nature Ecology and Evolution, the species Epiatheracerium itjilik — also dubbed the “Arctic rhino” — is considered the northernmost rhino species known to science.
“Today there are only five species of rhinos in Africa and Asia, but in the past they were found in Europe and North America, with more than 50 species known from the fossil record,” said Danielle Fraser, head of palaeobiology at the Canadian Museum of Nature (CMN) and the study’s lead author, in the press release.
“The addition of this Arctic species to the rhino family tree now offers new insights to our understanding of their evolutionary history,” Fraser added.
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Discovering the Arctic Rhino Fossil
The research team first found the Arctic rhino fossil in the Haughton Crater on Devon Island, Nunavut, a fossil-rich lake deposit. Miraculously, the fossil was nearly complete and it helped piece together more of the evolutionary history of the rhinoceros family.
According to a press release, rhinos have a long evolutionary history, spanning about 40 million years, and have lived on every continent except Antarctica and South America. The Arctic rhino lived during the Early Miocene — about 23 million years ago — and is closely related to other ancient rhino species that once lived in Europe millions of years ago.
The study authors also note that these new findings indicate that the Arctic rhino species likely crossed a land bridge from Europe millions of years later than previously thought.
Rhino Family History
Overhead view of the fossil of Epiatheracerium itjilik with its bones laid out on a sandy base. About 75 percent of the animal’s bones were recovered, including diagnostic parts such as the teeth, mandibles, and pieces of the cranium.
(Image Credit Pierre Poirier © Canadian Museum of Nature)
Not all ancient rhino species looked the same, or even similar, for that matter. Some of them were rather large and had an almost hippo-like body. Some, on the other hand, were rather small and hornless. The Arctic rhino fell into the latter category, similar in size to the Indian rhino, just without a horn.
According to the study, Mary Dawson, Curator Emeritus at the Carnegie Museum of Natural History in Pittsburgh, first found the fossil in 1986, including crucial identifiable bones such as the teeth, mandible, and even pieces of the skull. These findings helped researchers identify the bones as a new species. Dawson has since passed on, but is honored as the fourth author of the study.
“What’s remarkable about the Arctic rhino is that the fossil bones are in excellent condition. They are three-dimensionally preserved and have only been partially replaced by minerals, “ said palaeobiologist Marisa Gilbert, study co-author and Senior Research Assistant with the CMN, in a press release.
“About 75 percent of the skeleton was discovered, which is incredibly complete for a fossil,” Gilbert added.
The name Epiatheracerium itjilik comes from the Inuktitut words for “frost” or “frosty.” To honor the High Arctic home of the Arctic rhino, the research team consulted Jarloo Kiguktak, an Inuit Elder.
Crossing Into the Arctic
According to the study, the identification of this new Arctic species led the research team to look into the evolutionary and biogeographic history of rhinocerotids. To understand how this species evolved and dispersed across the Arctic, the team analyzed 57 other rhinocerotid taxa — most of which are now extinct.
From their results, the team could place each rhinocerotid specimen in one of five different continental regions. From there, they determined how these ancient rhino species migrated over a land bridge via Greenland — the North Atlantic Land Bridge — from Europe to North America.
While it was believed that animals used this land bridge to cross into North America about 56 million years ago, the new study indicates that animals were still using it much more recently, even during the Miocene, about 23 million to 5 million years ago.
“It’s always exciting and informative to describe a new species. But there is more that comes from the identification of Epiaceratherium itjilik, as our reconstructions of rhino evolution show that the North Atlantic played a much more important role in their evolution than previously thought,” Fraser said. “More broadly, this study reinforces that the Arctic continues to offer up new knowledge and discoveries that expand on our understanding of mammal diversification over time.”
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