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A pair of fossilized teeth confirms the presence of hyenas north of the Arctic Circle during the last ice age. The discovery fills an important fossil fossa that finally explains how hyenas found themselves in North America.
According to a new study published in the scientific journal Open Quaternary, a pair of isolated hyena teeth found in the Old Crow Basin of the Yukon Territory showed that hyenas occupied the Arctic during the last ice age. Palaeontologist Zhijie Jack Tseng of the University of Buffalo identified the teeth preserved at the Canadian Museum of Nature in Ottawa as belonging to the Chasmaporthetes genus, also known as "common hyenas" because of their generally longer legs than other hyenas.
The two isolated teeth have been identified from more than 50,000 mammalian fossils collected over the past 100 years in the Old Crow Basin. The hyena fossils were recovered in the 1970s and provisionally classified as hyenas. Tseng visited the museum in Ottawa earlier this year to take a closer look and, as an expert in hyenas, he immediately identified them as belonging to the Chasmaporthetes kind.
"The size, shape and arrangement of the cusps on both teeth are characteristic of the hyena. The teeth are very sturdy and have sharp blades, "Tseng said in an email to Gizmodo. "We also compared tooth measurements to a global sample of hyena fossil measurements."
The teeth were originally identified as belonging to another genus of hyenas, Adcrocuta. However, "on the basis of geological and geographical records of the two groups of different hyenas, we concluded that these specimens were unlikely to be adcrocuta"Tseng said.
Tseng explained that the identification of the teeth took so long, said the specimens were "out of sight, out of mind," hidden in a museum collection for decades. Only a few fossil hyena experts examined them, "and once we did, it was quite simple to identify and describe the specimens," he said.
Previously, paleontologists had discovered traces of ancient hyenas in Africa, Eurasia and southern North America. However, the lack of fossil evidence in the northern regions of the Arctic looked like a gigantic puzzle with a screaming hole in the middle. The two teeth of the hyena are the missing piece that completes the puzzle.
It is important to note that new evidence suggests that ancient hyenas moved from Eurasia to North America via the Beringian land mass during the last ice age, when the sea level was well below what it is today. We now have "physical evidence of Chasmpaporthetes travel or live in the Arctic region between their ancestral homeland in Asia and their new territory in North America, "Tseng told Gizmodo.
Humans took the same route to North America about 15,000 years ago, but hyena migration occurred much earlier. Researchers dated their teeth between 1.4 million and 850,000 years ago, with confidence being closer to older people. It is important to note that the first traces of hyenas in North America date back to five million years ago. The first hyenas must therefore have passed from Eurasia well before that date.
Surprisingly, the new evidence also fills a giant fossil gap – a distance of more than 10,000 km between known records of this new and old-fashioned lineage, according to the new study.
"It is amazing to imagine hyenas thriving in the harsh conditions that prevail over the Arctic Circle during the ice age," Yukon study co-author and paleontologist Grant Zazula said in a statement. published by the University of Buffalo. "Chasmaporthetes probably hunted flocks of caribou and ice age horses or mammoth carcasses recovered from the vast steppe-tundra that extends from Siberia to the Yukon Territory. "
In fact, these ancient Arctic hyenas, like those that still exist today, were both predators and scavengers. Scientists believed that Chasmaporthetes were less able to crack bones than other hyenas, but Tseng said they could bite the bones as well as they could cut the meat.
"So they represent the triple threat of a predator: they can run with their long legs, hunt and cut meat with their sharp teeth, and feed with their powerful premolar teeth," he said.
There are currently only four species of hyenas, but these animals were once diverse and included dozens of species that covered the northern hemisphere. By the time humans arrived in North America, hyenas had long since disappeared, disappearing at one point between 1 million and 500,000 years ago. The reasons for their extinction are not entirely clear, but it could have something to do with the competition of Arctodus simus-A short-faced bear whose North American rule lasted until the end of the last Ice Age, approximately 12,000 years ago.
Finally, Gizmodo asked Tseng about the extraordinary rendering of the ancient Arctic hyenas (shown above in its unframed form). He said his team was "very lucky" to collaborate with Canadian artist Julius Csotonyi on this incredible piece of art.
"We wanted to represent the Arctic in early spring, with local plants and animals. We wanted to be provocative with the pale fur of the hyenas, and speculate on the potential for camouflage that these arctic predators might have had, "said Tseng. "The mammoth baby represented some of the most common herbivores that may have fallen prey to hyenas. Julius used a "photorealistic" style of illustration that really takes us into the icy tundra of the ice age! "
