Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ The ancient rhinos roamed the Yukon

The ancient rhinos roamed the Yukon



  Ancient Rhinoceros roam the Yukon
The imagination of an artist for an ancient relative of today's rhinos splashing through the stream to turtles and fish in the Yukon. Credit: Julius Zotoni

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973, a teacher named Joan Hodgins took her students on a hike near Whitehorse in the territory of the Canada Yukon. In the process, she made history for this frosty region.


While exploring the tailings left by an existing copper mine, Hodgins and her students came across several fragments of fossils – pieces and pieces of what looked like teeth, along with pieces of bone.

The ancient tooth fragments were so small and in such bad shape that "most paleontologists may not have picked them up," says Jalin Eberle, curator of fossil vertebrates at the University of Colorado Boulder's Museum of Natural History.

But Hodgins did it. Now, more than 40 years after the teacher's fateful march, an international team led by Eberle has been using modern technology to identify the origin of these mysterious fossils.

In a study published today, Eberle and her colleagues report that fragments of fossil teeth may have come from the jaw of a long-lost cousin of today's rhinos. This heavy animal may have traveled through the forests of northwestern Canada about 8 to 9 million years ago.

And this is the first: Prior to the discovery of the rhino, paleontologists have not found a single fossil vertebrate dating back to that period in the Yukon

fierce lions, "said Grant Zazula, co-author of the new study and paleontologist at the Yukon government. "But this is the first time we have any evidence of ancient mammals, such as rhinos, dating back to the Ice Age."

  The ancient rhinos swam the Yukon
a series of fossils recovered by the Yukon. They are pieces of shells from two different species of turtle (top), a fossil from a relative of a modern pike fish (middle), and two fragments of ancient rhinoceros teeth (bottom). Credit: Grant Zazula

This is a gap in the record of fossils that scientists have been eager to fill.

To understand why, imagine Earth during the tertiary period, a period of time that began after the extinction of the dinosaurs and ended about 2.6 million years ago. In this era, a land bridge called Beringia connects what Russia and Alaska are today.

Paleontologists believe that animals of all kinds, including mammoths and rhinos, have spilled over this bridge.

There is only one problem: the geology and environment of the Yukon, which sat at the center of this mass migration route, does not favor the conservation of land fossils.

"We know that the land bridge must have operated for much of the last 66 million years," Eberl said. "The catch is finding the fossils in the right place at the right time."

In this case, the people at the right place and at the right time were the teacher of Yukon and her students.

When Eberle first saw Hodgins' fossil teeth now stored in the Yukon government's Whitehorse collections, she did not think she could handle them much.

  Ancient rhinos roam the Yukon
An enamel from a fragment of an ancient rhinoceros tooth, as seen by increasing levels of magnification. Credit: Gelin Eberle

Then she and her colleagues came up with the idea: Eberl put one of the small pieces under a tool called a scanning electron microscope that can reveal the structure of the tooth enamel with incredible detail.

She explained that mammalian teeth are not & # 39; t all built equally. Enamel-forming crystals can grow by following different patterns in different species of animals, a bit like a toothprint. The Yukon tooth team, according to the team, bore signs that it came from a relative of a rhino.

"I didn't think enamel could be so beautiful," says Eberl.

The method is not detailed enough to determine the exact type of rhino. But if this animal was anything like its contemporaries in the South, Eberl said, it could be about the same size or smaller than today's black rhinoceros and have looked at the maintenance list. He probably also didn't have a muzzle horn.

The group also examined a collection of fossils found along rhinoceroses. They belonged to two species of turtles, an ancient deer relative and a pike. The discovery of turtles, in particular, showed that the Yukon has a warmer and humid climate than it is today.

Hodgins, now retired, is excited to see what happens to the fossils she and her students discovered more than 40 years ago: "It's just so wonderful to learn what has evolved with them a long time ago," she said.

Eberle added that the newly discovered inhabitants of the Yukon rhinos are a testament to the importance of museums.

"the fact that these specimens were discovered in the collection of the Yukon Museum really makes me want to spend more time in other collections, including at CU Boulder, looking for similar discoveries that are there but have not yet had the right look for them, "Eberl said.


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More information:
Jaelyn Eberle et al., The First Tertiary Fossils of Mammals, Turtles, and Fishes of the Canadian Yukon, American Novitates American Museum (2019). DOI: 10.1206 / 3943.1

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The University of Colorado at Boulder
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Ancient Rhinoceros Wander the Yukon (2019, October 31)
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