It started on Wednesday, May 15, when a construction worker noticed that the dirt looked…different. He, along with other members of his team, were digging a hole in Highlands Ranch, where they’d soon construct new buildings for an independent living facility managed by Erickson Living, called Wind Crest. They got on their hands and knees to investigate. One said, “It looks like dinosaur bones.” Another countered, “Nah, it’s just trash.”

They called their boss.

David Rahm, a Brinkmann Constructors employee and project manager for the Wind Crest build, was in his office in Aurora when his phone rang. He quickly made his way to Highlands Ranch. When he arrived at the site, he found a hill cross-sectioned by construction equipment with rock, sand, and clay layered a bit like an unappetizing birthday cake. Sticking out of the earthy materials, he saw several bone-like protrusions.

The Denver Museum of Nature and Science investigates dinosaur bones found in Highlands Ranch
An exposed rib bone from a newly unearthed horned dinosaur at a Highlands
Ranch construction site. Courtesy of DMNS/Rick Wicker

Despite about 20 years working in construction, this was new. “I’ve found plenty of trash,” Rahm says. “I was part of a team that dug up napalm, stored in enough 55 gallon barrels to fill a few semi-trucks, in Southern California. But this is my first dinosaur.”

Rahm wasn’t sure who to call, but he certainly hadn’t signed up to lead a dinosaur dig, so he had one of his crew members reach out to the Denver Museum of Nature and Science. It was a good guess; a team of DMNS scientists asked for photographs, examined the images, and decided to check out the site in person.

When the DMNS team arrived the next morning, it was pretty clear that the Brinkmann crew had made a legitimate find. Several rib bones and what was later determined to be a foot-and-a-half-long humerus belonging to a horned dinosaur were identified in the Denver Formation, a rocky area thought to be between 66 and 68 million years old, says DMNS chief fossil preparator Natalie Toth. Thus commenced more digging: “So far, we’ve exposed about 20 elements or so from the skeleton,” Toth says. “A complete lower leg bone was found while removing some of the rocks around the site, and I’m hopeful there’s more.”

The snowstorm the night of May 20 hasn’t expedited the process. Moisture makes the dig site slippery, and also interferes with a process often used during excavations. Palentologists pour a consolidant over the bones, which fills any pores and stabilizes the fragments before they’re moved to the museum’s lab. Unfortunately, damp fossils inhibit the consolidant, which means Toth and her team haven’t made as much headway as they’d originally hoped.

A dinosaur bone found in Highlands Ranch by a Brinkman construction crew
An exposed limb bone from a newly unearthed horned dinosaur fossil at a
Highlands Ranch construction site. The Denver Museum of Nature and Science is evaluating the site. Courtesy of DMNS/Rick Wicker

Having an enthusiastic construction crew on hand could be the key to getting back on schedule, though. The Brinkmann team has been helping shift earth aside for the researchers, even as they continue construction on other parts of the property. “We’re lucky in that where we found the bones was outside our major work area,” Rahm says. “So the museum is able to do their part, and we’re able to do our part.”

It’s still too early to know exactly what’s been found—getting the bones into the DMNS fossil lab will help scientists better understand what they’re working with. That’s what happened back in 2017, when a Triceratops found at a Thornton construction site turned out to be a Torosaurus which is far more rare (it was the first one found in Colorado). The bones’ final home, too, is still in question. Turns out, donating or loaning fossils requires a lot of paperwork.

In the meantime, DMNS researchers, along with a team of volunteers, will help clean, sort, and identify the bones. Denverites curious about the discovery can join the museum on Facebook Live Thursday morning at 10:30, where several employees, including Toth, will be on hand to answer questions. “I think it’s really exciting,” Toth says. “I can’t think of many other museums across the country where you literally have dinosaurs in your back yard.”

Editor’s note, 5/23/19: The original version of this article stated that the Wind Crest property under construction is a continued care facility. It’s an independent living facility. The article has been updated to correct this error. 

Angela Ufheil
Angela Ufheil
Angela Ufheil is a Denver-based journalist and 5280's former digital senior associate editor.