Workers found 10,000-year-old mastodon bones at a while excavating a road at a housing development site in Byron Center, Mich., Aug. 31.
Developer Eagle Creek Homes now has five large bone pieces, along with some smaller fragments, WZZM 13 reported.
"My guys came across something that looked like logs and debris," said Joe Seireveld of Eagle Creek Homes. "As we're cleaning and washing it off, we're like, 'What is this?'"
"Lower jaw here," Seireveld continued. "That's was the kicker that went, we got something here."
A researcher from the University of Michigan came out to the site Sept. 5, and confirmed that the bones were, in fact, from a prehistoric male American mastodon that was between 20 and 30 years old when he died.
Eagle Creek said they are currently talking with the University of Michigan about donating the bones and continuing to work as a team at the construction site, WZZM 13 reported.
Just last month, construction workers uncovered triceratops bones and a skull at a site in Colorado.
