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Eric Stamatin’s expeditions into his family’s wooded suburban Detroit backyard have yielded plenty of interesting finds, but none to rival the 13,000-year-old artifact he and his cousin dug up last summer.

Eric and cousin Andrew Gainariu, who are both 11, were building a dam in the creek that flows through the yard when Eric saw a strange-looking rock sticking up from the ground. At least, he thought it was a rock.

"My cousin said, ‘Hey wait a minute, I think this is a bone.’" — Eric Stamatin, 11

“We thought it might be a cool-looking rock, because I see a lot of those, until my cousin said, ‘Hey wait a minute, I think this is a bone,’" Eric told FoxNews.com. "I said, ‘I’m really not sure, let’s go home and show my Dad.’ My Dad’s a doctor. So my Dad looked at it and said, ‘Yep, it’s a bone.’”

More specific scientific verification came last month, when paleontolgist John Zawiskie authenticated the bone as a vertebrae from a mastodon. Zawiskie saw a cellphone photo Cristina Stamatin sent him, and he immediately knew “there was no mistaking this was from a mastodon,” the furry elephant-like creature that went extinct about 12,000 years ago, after a 3.7 million-year run on Earth.

Zawiskie is accustomed of letting people down easy when their "finds" turn out to be ordinary, but this time he got excited.

"‘You know, it’s people calling to say, ‘I found a meteorite or, ‘I found a dinosaur egg,’ or ‘I found a dinosaur bone,’” Zawiskie said. “The last one I got two days ago concerned a petrified horn that turned out to be fossilized coral.

“We’re always running down finds like this as paleontologists, but I immediately recognized that this was more than just a mastodon find. It was a cool story that I knew it would resonate, said Zawiskie, who works at the Cranbrook Institute of Science, in Bloomfield Hills, Mich. “Many people in childhood have this very same fantasy, to dig in their backyard and unearth a fossil of some sort or artifact of some significance. And this was authentic, the real thing."

Authentication from Zawiskie, who said there have been about 200 such finds in southern Michigan in the past 150 years, renewed the joy the boys felt in July, when they made a find that ranks in childhood fantasies with unearthing pirate's treasure.

“Santa (Claus) came in the middle of the summer, and gave me one of my presents early,” Eric said.

Zawiskie inspected the site, wading through the creek with the boys before determining that there are probably no more such artifacts in the area. But Eric and Andrew, who visited Zawiskie at his laboratory, aren't taking his word for it: They've been digging up the yard every chance they get.

"Who knows what he'll find back there next?" Cristina Stamatin said. "You should see all the things he collects.

"Usually, they’re absolutely covered with mud," she added. "Oh yeah, it’s a mother’s dream.”