A dinosaur that once roamed what is now Highlands Ranch met the open air for the first time in more than 66 million years, after a construction crew discovered its bones at a construction site in mid-May.

A crew from Brinkmann Constructors building an expansion onto the Wind Crest retirement community near C-470 and Santa Fe Drive happened upon the fossilized bones, said Salvador Bastien, a fossil preparator with the Denver Museum of Nature and Science.

“We're really excited they realized they were hitting bones,” Bastien said. “Lots of times, people don't notice, or if they do, they just keep going.”

Construction crews working on private property in Colorado are under no obligation to notify anyone or halt work if they find fossils, Bastien said.

Volunteer crews led by paleontologists from the museum will excavate the site in coming weeks, Bastien said, while construction work continues on other parts of the site. The site is not open to the public.

Though it's a little early to say for sure, Bastien said the fossils appear to be from a triceratops, a three-horned herbivore that often grew to be 30 feet long and 10 feet tall. The fossils are from the late Cretaceous era, and are likely 66 million to 68 million years old. Dinosaurs went extinct about 65 million years ago.

Triceratops are among the more common dinosaurs found in what's called the Denver Formation, Bastien said. The formation was once a broad, forested river system, and triceratops appear to have been plentiful.

“Think of them like bison roaming the landscape,” Bastien said.

How the find will contribute to the scientific record depends on what researchers uncover, Bastien said.

“We don't have X-ray vision, so we don't know what else is lying in that hillside,” he said. So far, crews have found arm bones, ribs, and what may be skull bones.

Colorado's Front Range is rich with fossils, Bastien said, because the geologic uplift that pushed the Rocky Mountains above ground cracked open layers of sedimentary rock that once sat over them, providing remarkable cross-sections of geologic history.

“It's a really exciting place to be if you're a paleontologist,” Bastien said.

The find is exciting for Wind Crest as well.

“On behalf of the residents and employees of Wind Crest, we are thrilled to be part of such an incredible scientific discovery,” Craig Erickson, Wind Crest's executive director, said in a news release. “We appreciate the invaluable expertise of the Denver Museum of Nature and Science and our partners at Erickson Living and Brinkmann Constructors as we work together on this exciting opportunity for all of us to learn more about our earth's rich history.”

Brinkmann Construction also thanked Wind Crest and the museum in the news release.

“This is a remarkable discovery that our team takes great pride in unearthing,” said David Rahm, a Brinkmann project director.

Bastien said he's excited to get the fossils back to the museum's lab, where volunteers will slowly clean them for addition to the museum's collection.

In the meantime, Bastien encouraged locals to take a close look at their surroundings.

“This is such a wonderful area to find fossils," Bastien said, "so keep your eyes peeled."