By Published: Feb. 11, 2019

stegosaurus fossils

Origins: Stegosaurus 

You’d probably identify the giant wall-mounted fossil inside the Jerry Crail Johnson Earth Sciences & Map Library as a dinosaur. If you’re a dinosaur buff, you might even suspect it’s a Stegosaurus.

It’s better than that: The replica, one of just two in the world, depicts the most complete Stegosaurus skeleton ever found. 

Kenneth Carpenter (PhDPaleo’96) can tell you all about it.

dinosaur graphic

In June 1992, Bryan Small, Carpenter’s assistant, was standing in a ravine in Garden Park, near Cañon City, Colorado, when he scraped a rock hammer across a bone, knocking it loose.

To his immense surprise, it turned out to be a fossilized vertebra of a Stegosaurus Stenops, an herbivorous dinosaur with rows of upright plates along its back that walked the Earth between 150 and 155 million years ago. The next day, they returned with shovels, jackhammers and chisels.

For the rest of the summer, Carpenter and a group of skilled volunteers from the museum and the Garden Park Paleontology Society spent long days (and some nights) chipping away at the rock.

With the help of a skilled mining crew, hundreds of hours of careful excavating and a heavy dose of creativity, Carpenter and team unearthed a skeleton that was nearly 80 percent complete — missing only the front two legs and a partial hind leg, which they hypothesize were snatched away by scavengers after the animal died.

When they finally made it to the tail, they found three of the four iconic tail spikes were still attached. For Carpenter, the fourth spike held the key to how the great dinosaur had died — a bone infection.

The summer-long dig was challenging: Apart from the skull and a few vertebra, most of the skeleton was buried under 15 feet of rock in a steep ravine in a remote area. Temperatures were often high, sometimes in the high 90s, and there were swarms of gnats, flash flooding and frequent thunderstorms.

But the researchers were too excited to care.

Once the skeleton was unearthed, the researchers had to find a way to get it out of the ravine and into the lab. Because of the steep terrain, using a backhoe or truck was out of the question. They could have broken the skeleton into pieces, but they were determined to keep the nearly completely intact skeleton as undisturbed as possible.

“The only way was to airlift it out,” said Carpenter.

On Aug. 14, 1992, after many hours of preparation, observers on a nearby hill saw the dinosaur's body take to the sky, suspended by a CH-47 Chinook helicopter  — a military aircraft used for lifting heavy artillery in and out of combat. Including the fossil’s protective jacket, made of plaster and burlap sacks, the fossil weighed 6.5 tons.

The helicopter pilot told me that the Stegosaurus plaster cradle was at the maximum limit they could carry, and he came close to releasing it,” said Carpenter, now director and curator of paleontology at Utah State University.

There were no local facilities for preparing scientific specimens, but a local monk invited researchers to store and work on the fossil in his nearby abbey’s garage. It remained there until a dinosaur museum opened in Cañon City in 1995.

The next year Carpenter and team shipped the fossil off to its final destination: the Denver Museum of Nature and Science.  

In 1996, CU Boulder acquired one of two plaster copies of the fossil for Benson Earth Sciences, then newly opened. It has hung on the wall there since 2001. The original rests in a storage facility at the Denver Museum of Nature and Science — waiting to be unearthed again.

Photo by Deirdre O. Keating