Robert Kyikavichik was duck hunting on the Crow River in northern Yukon when he saw something protruding from the water.

"We just noticed an unusual bone sticking up … so we went to check it out," he said.

"When I'm travelling along the river, up the Crow, you always keep an eye out for stuff like that, but I didn't expect to come upon something like this."

A paleontologist confirmed the find is definitely a woolly mammoth femur bone.

It's at least 11,000 years old, and it could be a whole lot older. It may be from one of the first woolly mammoths to ever lumber across North America, a million years ago.

Robert Kyikavichik of Old Crow, Yukon, with a woolly mammoth bone he found about 100 kilometres outside the community. (submitted by Marla Charlie)

Kyikavichik, who lives in Old Crow, said he found the bone while he was out duck hunting with his young son and nephew on the weekend, about 100 kilometres up the Crow River from his community of about 250.

He immediately hauled it aboard, to the delight of his son and nephew.

"They were pretty excited about it — they've never seen something like that before. I was teasing them, telling them it was a dinosaur bone, but I knew it was a mammoth bone."

It's not unusual to find old bones or fossils in northern Yukon. Kyikavichik has found smaller mammoth bones and even teeth before, but "nothing that big."

'Pretty nice' find, says paleontologist

Yukon government paleontologist Grant Zazula has not yet seen the bone up close, but he saw a picture that went viral on social media Tuesday morning.

Definitely a woolly mammoth femur bone, he said — from the thigh, connected to the hip bone.

"Pretty impressive," he said — not because it's extremely rare, but because it appears to be a good specimen, surprisingly intact.

"We don't usually find complete bones in that area because they've been rolling around in a river and getting banged up by rocks and other things.

"So to find something fairly complete like that is pretty nice."

'To find something fairly complete like that is pretty nice,' says Grant Zazula, a paleontologist with the government of Yukon. (CBC)

Zazula calls the area around the Crow and Porcupine rivers "some of the richest Ice Age paleontological deposits on the planet."

"Literally on every turn of the river, on every little point bar, they can just be layered with ice age fossils," he said.

Zazula said it's hard to say how old the bone is just by looking at it. Carbon dating will give a better idea.

The last woolly mammoths lived in Yukon about 11,000 years ago, so it's at least that old, he said.

It could even be up to a million years old, dating from the time when mammoths first arrived in North America, via the Bering land bridge.

"Any mammoth remains from Old Crow are definitely scientifically significant because there's potential they could represent those earliest ancestral North American mammoths that entered from Asia.

"So it's pretty cool, definitely," Zazula said.

The bone will likely stay in Old Crow, to be added to a local research collection held by the Vuntut Gwitchin First Nation.