Picture the scene: a muggy afternoon, 66 million years ago, on a mucky river delta. Crocodiles and turtles crawl among flowers and ferns beneath towering sycamores. On the river bank, a 30-foot triceratops lies dead, partially sunken in the mud.

Fast-forward to 2019. The river delta, now beneath Highlands Ranch, has yielded the bones of the dinosaur, long since fossilized.

A volunteer crew from the Denver Museum of Nature & Science wrapped up the dino dig in mid-July, and said they recovered about a third of the ancient three-horned herbivore.

The fossils — including portions of the dinosaur’s skull, ribs, hips, shoulder blades and backbone — are available for public viewing through the window of the fossil preparation lab at the museum, said fossil preparator Salvador Bastien, who worked on the dig.

A crew from Brinkmann Constructors building an expansion onto the Wind Crest retirement community near C-470 and Santa Fe Drive happened upon the fossils in May, Bastien said, and invited the museum to excavate them.

The bones were scattered and scrambled in an area stretching across 50 to 60 feet, Bastien said, suggesting they may have been moved by the river or scavengers after the dinosaur died and decomposed.

The fossils were buried in sandstone and mudstone, suggesting the animal died in a river channel, Bastien said, and the remainder of the bones probably long since wore away.

Initial research hasn’t suggested a cause of death, which is extremely difficult to determine, Bastien said.

Triceratops were among the most common types of dinosaurs in the Cretaceous Period, Bastien said, which ended with the extinction of the dinosaurs 65 million years ago.

Though paleontologists are already well-acquainted with triceratops, “every fossil is rare, and each one has the potential to increase our understanding of ancient ecosystems and biology,” Bastien said.

Crews called it quits after finding no more fossils in a one-meter radius from those already recovered, Bastien said. It’s possible there are more fossils to be found at the site, but “we don’t have X-ray vision.”

The fossils were brought to the museum wrapped in plaster and burlap, Bastien said. Next they’ll be painstakingly cleaned with hand tools like dental picks and toothbrushes.

Though the lab has many projects going right now, this one will be prioritized because of its interest to the community, Bastien said. It’s too soon to say if the bones will eventually be added to a public display, though they will become part of the museum’s collection.

Under Colorado law, Bastien said, fossils discovered on private land are the property of the landowner, so he’s thankful that Wind Crest decided to donate the fossils to the museum. He’s also thankful that construction crews realized what they found and bothered to tell the museum.

The discovery has been a joy for Wind Crest too, said Craig Erickson, the company’s executive director.

“The discovery and excavation of the Triceratops fossils on campus has been a thrilling experience for our residents and staff,” Erickson said in a news release. “It is our honor to donate these incredible artifacts to the Denver Museum of Nature & Science for further study. We are grateful to the museum’s expert staff and the team at Brinkmann Constructors for their partnership in preserving this this important part of Colorado history and sharing it with the greater community.”