The Denver Museum of Nature and Science has sent researchers everywhere from North Dakota to Antarctica in search of fossils to study and display. It turns out they could have stayed home.
The museum discovered fossilized dinosaur bones in its parking lot in January while drilling test holes for a geothermal energy project, it announced Tuesday.
Knowing they would be burrowing almost 1,000 feet deep into ancient rock that dated back over 65 million years to the Late Cretaceous period, the museum’s scientists decided to use the opportunity to extract rock samples for study.
One rock they found looked different — pale, spongy and brittle, a little smaller than a soup can. It caught the attention of researcher Bob Raynolds, who quickly called his colleagues.
“Bob called me and said, ‘I think we found a dinosaur,’” James Hagadorn, the museum’s curator of geology, recalled.
Researchers determined they’d unearthed several pieces of vertebrae from a plant-eating dinosaur — exact species unknown — buried 763 feet below the Denver Museum of Nature and Science. It is around 67.5 million years old, the oldest and deepest dinosaur fossil discovered within the city limits, the museum said.
“My jaw fell on the floor,” Hagadorn said. “My eyes were about as big as saucers.”
Denver has long been a happy hunting ground for paleontologists. Several construction projects in the city have unearthed fossils for study. Workers found dinosaur bones while building Coors Field, the home of the Colorado Rockies (and their mascot, a triceratops).
But the Denver Museum of Nature and Science never thought to check 700 feet below the surface of its own land until January when, funded by a state grant, workers bored holes deep into its foundation to assess the feasibility of installing a geothermal energy system.
It was an extraordinary stroke of luck that the narrow cylinder of land — around 2.5 inches in diameter, and extending about 1,000 feet below the surface — that the museum chose to sample ended up containing a fossil, Hagadorn said.
Museum staff carefully reassembled the fossil fragments to confirm they’d found dinosaur bones. Raynolds was “100 percent sure the second he saw it,” Hagadorn said. But the museum waited until July to announce the discovery, after a paper by Hagadorn, Raynolds and their colleagues on the fossil was peer-reviewed.
Researchers pegged the shape of the fossil — like a stack of poker chips or a hamburger, Hagadorn said — for a series of vertebrae, according to the study. The bones unearthed were enough to indicate the dinosaur was an ornithopod, a category of medium-sized herbivores, but researchers could not pin down its species.
The ornithopod would have roamed the Colorado capital tens of millions of years ago when the city was a lush tropical forest, Hagadorn said. Nearby, the Rocky Mountains were only beginning to rise. The dinosaur’s predators could have included the Tyrannosaurus rex, which lived around the same period. Fossilized alongside its bones were parts of prehistoric plants, which could have been the trees it lived under or its final meal.
Hagadorn and Raynolds’s study notes that it’s possible other drilling projects across Denver and surrounding regions could have intersected with dinosaur fossils, but rock samples are rarely kept and analyzed.
“This type of discovery is an important reminder for local communities that science is literally being done below their feet,” the study states.
The ornithopod bones are now on display on the first floor of the museum in a larger dinosaur exhibit headlined by another serendipitous discovery: a teenage T. rex fossil unearthed by a North Dakota family in 2022.
Fossils are often only discovered in fragments. But there remains the enticing possibility that more of Denver’s oldest dinosaur could still be buried deep underneath the museum. Would it be worth looking for it?
“I think the museum would fall into the hole if we dug a hole that big,” Hagadorn said.