Last week, a construction crew was digging during work on a new fire and police building in Thornton, Colorado when they unearthed a prehistoric treasure: an ancient triceratops fossil.

The discovery is especially notable because the remains include the triceratops skull—one of just three believed to have ever been dug up in the Front Range of the Rocky Mountain, reports Danika Worthington for the Denver Post.

“I’m over the moon right now about this dinosaur fossil," paleontologist Joe Sertich of the Denver Museum of Nature & Science says in a statement about the discovery. Thornton officials brought Sertich in earlier this week to confirm the discovery and begin the work to excavate it. He hopes to see the fossil exhibited in his museum once it's dug up and preserved.

The remains are older than most other fossils found along the Front Range, which usually originate from the end of the last ice age, around 10 to 12 thousand years ago, according to Sertich. The triceratops, however, dates back to at least 66 million years ago, when the creatures are thought to have gone extinct after a six-mile wide asteroid collided with Earth. In the densely populated and heavily paved metropolitan area, people rarely dig far enough down to reach some of these older layers that contain dinosaur fossils, Worthington reports. And when they do, they often are just plowed right over, Sertich notes in the release.

Triceratops have long captured the imagination of dinosaur lovers. The first skeleton was assembled and mounted in an exhibit at the Smithsonian's National Museum of Natural History in 1905. Named "Hatcher" in honor of pioneering paleontologist John Bell Hatcher, who discovered most of its bones, the beast was cobbled together from a patchwork of parts. It was hardly anatomically accurate, but it was still awe-inspiring to visitors. That year, The Washington Post called it "the most fantastic and grotesque of all that race of giant lizards known as dinosaurs," writes Sarah Kaplan of The Washington Post in an article describing a forthcoming exhibit that includes "Hatcher."

Triceratops was among the last living dinosaur species. This large, herbivorous dinosaur sported two horns on its forehead and one at the tip of its snout (its name literally means "three-horned face"). Through the years, triceratops has become famous in pop culture, making appearances in films including "Jurassic Park" and "The Land Before Time." It has even made its way onto postage stamps.

"It is incredible to have this find occur in our backyard," Sertich said in a statement. "Finds like this help us to understand dinosaur evolution and behavior.”