A pair of fossilized teeth found near Old Crow, Yukon, in the 1970s finally reveal the migratory trajectory of ancient hyena species that found their way into the northern tundra during the last Ice Age.
Yukon government palaeontologist Grant Zazula had suspected for years that teeth belonged to a genus of hyenas. But it was not until Jack Tseng, an evolutionary biologist and early mammal predators from the University of Buffalo, had come to confirm his suspicions.
Grant Zazula and Jack Tseng published the results of their study Tuesday in the journal Open Quaternary.
“During most of the ice age, there was a variety of strange animals that shuttled through the Yukon through the Bering Strait land bridge. They traveled all over North America and Asia, “says Zazula.
They leave little clues of their passage behind them and these fossils are an example.
Grant Zazula, Yukon Government paleontologist
The fossils belong to a genus of hyenas called Chasmaporthetes . They were discovered by Charlie Thomas, a Gwich’in First Nation elder who was working with scientists in the 1970s.
Other Chasmaporthetes fossils have been found in Mexico and Mongolia, but never in between.
The Chasmaporthetes are the only type of hyenas found outside of Europe, Asia or Africa.
Passage of hyenas
“Approximately 6000 kilometers separate the two sites of Mexico and Mongolia,” says Grant Zazula. “So everyone thought that hyenas had to cross the Yukon through the Bering land bridge and enter North America through this passage,” he says.
“We had never been able to prove that this was the case because there was never any physical evidence found in the Yukon. ”
The chasmaporthetes would have been about the same size as modern hyenas, but with longer legs to help them move more efficiently over long distances.
This detail is important because the chasmaporthetes would have been hunters, in addition to being scavengers. Grant Zazula believes that tall grasses found in the tundra at the time would have been an ideal habitat for camels, caribou and mammoths from the Ice Age, ideal prey for hyenas.
Skillful “bone breakers”
“They were probably very good bone breakers,” says Jack Tseng. “Do not get me wrong, they were good hunters all the same, but when they had to eat carrion, they could clean a carcass like no other predator.”
At this stage of the study, scientists can only give an approximation of the time that chasmaporthetes spent in the Yukon.
While the age of fossils found near Old Crow is estimated between 850,000 years and 1.4 million years ago, the first wave of chasmaporthetes fossils found in Mexico and the southern United States dates back to 4, 75 million years.
Teeth prove, however, that the hyenas passed through the Bering Strait to head south of the continent.
“We have found more than 50,000 bones of ice age animals in the Old Crow area, but we have only two hyena teeth,” says Zazula.
“So it’s a rare animal. The discovery of these fossils is very significant, “he says.