The scientists from Denver Museum of Nature and Science visited the building site to inspect the rare discovery which they believe to be around 66 million years old.

Joe Sertich, the museum’s curator of dinosaurs, said it’s one of only three triceratops skulls found in the Front Range area.

“A lot of times these will be plowed up and they won’t be recognized,” Sertich told WFMY News. “We’re really lucky in this case that it was recognized as fossils and we got the call.”

The triceratops was at least 66 million years old – something a little different from the 10,000 to 12,000-year-old fossils Sertich says are usually found in the Denver area.

The difference in this case was construction workers were digging deeper for this building than they usually do to build parking lots and other structures – something that allowed them to get closer to an era when dinosaurs roamed the Earth.

“My heart was racing!” Sertich said. “As soon as uncovered it and realized this was a horn of a triceratops and not just another leg bone or part of a hip, it made the site really exciting.”

Construction has stopped in the area so scientists can expose the fossil, look for other bones and then extract them, the city of Thornton said.

When the fossil is safely removed, the hope is that one day it will be housed at the Denver Museum of Nature and Science.

“As soon as I got onsite, I realized it was a pretty important dinosaur find, which are pretty unusual in the Denver area,” Sertich said.