Construction workers sometimes find themselves moonlighting as paleontologists after inadvertently digging up the remains of prehistoric creatures. In August, for example, a crew in Thornton, Colorado, found a 66-million-year-old adult triceratops skeleton while breaking ground for a public safety facility. Now, hot on the heels of that discovery, the Associated Press reports that workers in Michigan have unearthed bones that belonged to a male American mastodon that died between 10,000 and 12,000 years ago.

The discovery took place in the small town of Byron Center on August 31, when contractors for local home building company Eagle Creek Homes LLC stumbled across the bones while preparing the site of a new housing development.

"Our excavation crew, Bultema Excavating, was digging out a mucky soil area to move to another area in the development when they discovered something unusual in a load of muck," Joe Siereveld, an owner and partner in Eagle Creek Homes, tells Mental Floss. "Closer examination revealed that they were some type of large bones."

At this point, Eagle Creek Homes contacted experts at the University of Michigan to help identify the remains. There, Dan Fisher, director of the university's paleontology museum, "confirmed the bones belonged to a 20-to-30-year-old male mastodon that lived 10,000 to 12,000 years ago," Siereveld says.

Workers initially found only three large bones, but they've since dug up 12 more skeleton fragments, according to Siereveld. He and his business partner, Mike Siereveld, plan to donate their growing fossil collection—which appears to include parts of the extinct mammal's lower jaw, skull, limb bones, pelvis, and spine—to the University of Michigan for research and display.

For Mike Siereveld, the find was "a once-in-a-lifetime experience," he tells Mental Floss. But according to Fisher, it's not uncommon to find fossils like this in Michigan, as both mastodons and mammoths were once drawn to the region's lakes and vegetation. He estimates that around two to three similar discoveries are made in Michigan each year.

But occasionally, these kinds of bones can help scientists draw exciting new conclusions about early life in the Americas. In 2015, for example, Fisher was called to the scene after farmers in the state's Washtenaw County found a remarkably intact wooly mammoth skeleton. Evidence suggests that the mammal had been hunted and killed by humans 15,000 years ago—around 2000 years before humans are believed to have arrived in Michigan.

Check out more pictures of the newly discovered Michigan mastodon skeleton below:

Mike Siereveld

Mike Siereveld

[h/t AP]