A 57,000-year-old mummified wolf pup was found in Yukon permafrost. It's so well preserved that everything but the eyes is intact.

• A gold miner in Canada's Yukon found the 57,000-year-old body of a female wolf pup in melting permafrost.
• According to a new study, it is the most complete wolf mummy ever found.
• The wolf's fur, teeth, and soft tissues are intact — only the eyes are missing.
• Researchers think the 7-week-old pup died after her den collapsed.

A 7-week-old gray wolf pup was in her den in the Canadian Yukon 57,000 years ago when it suddenly collapsed. The animal was killed instantly, but the wolf was frozen intact and buried under permafrost.

The cold meant that the body barely decayed over the subsequent millennia.

"She is complete, with all her soft tissues intact and even her fur. This is a very rare find," Julie Meachen, a professor of anatomy at Des Moines University, told Business Insider.

Meachen is the lead author of a study about the wolf, published Monday in the journal Current Biology.

The carcass, which a miner found in the Klondike gold fields in 2016, is the most complete wolf mummy ever seen, Meachen added. Her team named the pup Zhùr, which means "wolf" in the local indigenous Hän language.

"Since Zhùr was so intact, we can learn a lot from her short life," Meachen said.

By examining the tiny body, researchers can glean clues about what the Earth was like during an era when it was much colder and broad swaths of the world were covered in ice. They can also find out how ancient wolves lived and what they ate.

Every part of the wolf pup was intact except the eyes

Meachen said handling the wolf's body felt exhilarating.

"I was very ginger with her as I didn't want to damage anything," she said.

Meachen and her colleagues took X-rays of Zhùr's skeleton and analyzed samples of its fur and tooth enamel. They found that the pup's bones had not yet fully developed, which is how they determined it was just seven weeks old at the time of death. The body is just over a foot long and weighs 1.5 pounds.

They knew the pup was female, since the genitalia was perfectly preserved.

The only parts Zhùr was missing were her eyes.

"Eyes are very soft and gelatinous, so they are the first thing to disintegrate when an animal dies," Meachen said. "The eyes are open to the elements and bacteria, and they probably desiccated quickly, which is why they appeared so shriveled and seem completely absent."

By analyzing traces of minerals in the pup's tooth enamel, the researchers found that Zhùr had most likely been weaned recently, and that the wolf family's diet consisted of fish - possibly salmon - from the nearby Klondike River.

The team also compared Zhùr's DNA to that of modern-day wolves. They found that the mummified pup was related to ancient gray wolves that once lived in Eurasia, as well as modern gray wolves from North America. The genetic similarities suggest Zhùr's ancestors migrated between the two continents using the Bering Land Bridge.

The nature of Zhùr's death kept the wolf preserved

It's unusual, Meachen said, to find intact animal mummies in the Yukon.

"The animal has to die in a permafrost location, where the ground is frozen all the time, and they have to get buried very quickly, like any other fossilization process," Meachen said in a press release. "If it lays out on the frozen tundra too long, it'll decompose or get eaten."

The analysis of Zhùr's diet suggested the animal didn't starve to death. That's why Meachen thinks the pup died instantaneously when its den unexpectedly collapsed.

"We've been asked why she was the only wolf found in the den, and what happened to her mom or siblings," she said. "It could be that she was an only pup. Or the other wolves weren't in the den during the collapse. Unfortunately, we'll never know."

As the Earth warms, more animal mummies are emerging from the permafrost

Discoveries like this one are likely to become more common as Earth's temperatures continue to rise.

As the planet warms, the permafrost - ground in the Northern Hemisphere that remains frozen all year - is beginning to thaw. As it melts, ice-age creatures like Zhùr that were entombed for tens of thousands of years are starting to be unearthed.

"That is probably the only silver lining to global warming," Meachen said. "Scientists are delighted to find these mummies, and horrified simultaneously because we understand what the implications are for continued climate change."

In a similar finding in September, Siberian researchers announced they'd found a perfectly preserved adult cave bear - with its nose, teeth, and internal organs still intact. Scientists think the bear died 22,000 to 39,500 years ago. Its species, Ursus spelaeus, lived during the last Ice Age and then went extinct 15,000 years ago.

The Lyakhovsky Islands, where the bear was found, are also replete with remains of woolly mammoths from the last ice age.

In nearby Yakutia, scientists discovered a 40,000-year-old severed wolf's head, complete with fur, teeth, brain, and facial tissue on the banks of a river in 2019.

Siberian permafrost has also revealed two perfectly preserved, extinct cave lion cubs, as well as an ancient, baby horse that died in a mud pit 42,000 years ago. The foal's hair, skin, tail, and hooves were all intact.