Denver Museum of Nature & Science has a little something for everyone, from gemstones, to Martian dust devils, to wildlife and even some mischievous, well-hidden elves. But for some visitors, it’s all about one thing: dinosaurs.

By the time you’ve walked through the museum’s Prehistoric Journey exhibit, you will have encountered hundreds of dinosaur fossils. But before they were mounted into display cases or assembled into skeletons or added to one of the Touch Carts (yes, you can touch some of the fossils!), about 75 percent of the fossils on display passed through the Schlessman Family Laboratory of Earth Sciences, a.k.a. the Fossil Prep Lab.

Denver’s Fossil Prep Lab opened in 1990, and it has helped the museum’s Earth Sciences department process thousands of fossils from excavations across the globe in places like Madagascar, Egypt and Kenya. However, one of the lab’s most recent — and most exciting — projects is from just a few miles up the road.

In August of 2017, construction workers in Thornton, Colo., discovered dinosaur bones while digging the foundation for a new police and fire substation. A visit from Joseph Sertich, the museum’s curator of dinosaurs, confirmed the find and revealed the mystery dino to be a 66-million-year-old Triceratops, at least initially.

A fast-paced excavation began. Within a few weeks, the dinosaur — now nicknamed “Tiny” — was unearthed.

“If this had been found in the field, the excavation could have taken up to two years,” says Patrick Sullivan, a volunteer in the lab.

“But here, there were plenty of volunteer dig assistants from the museum, as well as the police and firefighters who would eventually be using the building. Plus, there was the time pressure for the construction — so everything went a lot faster than it normally would have.”

All told, the team recovered about 95 percent of the dinosaur’s skull and 25–30 percent of the skeleton, making it the most complete Cretaceous Period fossil in the state.

But about a month after the creature arrived in the lab, it suddenly went from being an exciting find to a BFD — a Big Fossil Deal.

Denver Museum of Nature & Science's fossil prep labAs the field jackets (wrappings made from plaster and burlap used to protect fossils during transport and storage) were unwrapped and the individual bones revealed, Sertich realized that what he initially thought to be a Triceratops was actually a much rarer dinosaur called a Torosaurus. While the Triceratops was a fairly common dinosaur in the West (more than 2,000 individuals have been found in the region), only around seven partial Torosaurus skulls have ever been recovered. This specimen is the only one found in Colorado, and the most complete skeleton in the world.

“It’s an incredibly important paleontological discovery,” says Sullivan. “Every rib is the first of its kind ever recovered. Every bone is worth being studied.”

“There are going to be a lot of papers coming out of this museum in the next few years,” adds Maura O’Neal, the museum’s communications and media relations manager.

Sertich estimates that it will take several more months to meticulously clean away all the sand and rock surrounding the Torosaurus bones. You might think that such important work would only be carried out by the most highly trained and experienced fossil preparators behind closed doors. But you’d be wrong on both counts. Although supervised by Sertich and a handful of staff preparators, the bulk of the work is carried out by the Fossil Prep Lab’s more than 125 volunteers, including Sullivan, who has been donating his time and talents in the lab for about nine months.

And it all happens in full view of the public, which is what makes the Fossil Prep Lab especially exciting for museum visitors: the lab is surrounded on two sides by sliding, wall-to-wall windows, allowing you to watch the volunteer preparators at work and ask them questions. You’ll also find signs with information about the particular fossils that are being worked on. For instance, today, the sign points out the Torosaurus humerus (upper arm bone), eye horn, nose, frill and ribs. There are even plastic Triceratops and Torosaurus toys on display to illustrate the differences between the two Cretaceous cousins.  

Also on display in the lab: a nearly complete Stegosaurus skeleton that has been flattened like a pancake by millions of years of geologic pressure and an Ophthalmosaurus — an ancient marine reptile with a giant eye (hence the name) that swam the waters of Wyoming’s interior sea 160–145 million years ago.              

Once cleaned, the fossils go into the museum’s recently completed underground collections space, where they are catalogued for researchers to access and study. Some are periodically loaned out to other museums and research institutions. Only a fraction end up on display in the museum — which makes getting the chance to view them in the Fossil Prep Lab a real treat!

Visit the Schlessman Family Earth Sciences Laboratory at Denver Museum of Nature & Science at the end of the Prehistoric Journey exhibit on the third floor. The lab is open and viewable during museum hours. 

Interested in volunteering? Fossil Prep Lab volunteers must be at least 17 years old and receive training by DNMS staff preparators (offered quarterly). Check the museum’s website for openings.

Photo credit: Volunteer Mike Lacey working on a specimen. Photo courtesy of the museum.