For nearly 40 years, the Weld County Triceratops – affectionately known as “Pops” — has been stuck in an awkward spot for a fossil of its stature. A dinosaur for the people, Pops has been a very public figure, on display behind glass in various county buildings.
Yet the most complete horned dinosaur skull ever found in Colorado had never been thoroughly examined by paleontologists — it was essentially lost to science.Thanks to a new agreement between Weld County leadership and researchers at the Denver Museum of Nature and Science, that has now changed.
“We’re using this to remove the plaster cleanly from the fossil so that we can see all of the actual bone and study the true shape of what this animal would look like in life,” he explained. The air scribe is slowly revealing bone that adds a new twist to the story of the Weld County Triceratops: the creature is likely not a Triceratops at all. Hundreds of millions of years ago, “the whole state of Colorado was under water,” Evanoff explained.
“And then we ended up with lowland rivers in the area, and that’s where the deposits of dinosaurs occurred.”Many of those deposits are from the late Cretaceous period, meaning the tail end of the very long age of the dinosaurs. And one of those areas of rich deposits is Weld County.
One day, Ken Carpenter — who went on to have a storied career in paleontology — asked his friend Evanoff for a hand in the field. Their destination was the Seven Cross Ranch northeast of Greeley, where they spent the day collecting micro fossils.
Evanoff is now a professor of geology at the University of Northern Colorado. He said they had just about wrapped up for the day when Carpenter caught a second wind for another round of prospecting.“Ken’s kind of a funny guy.
He is very serious when he’s out in the field. He doesn’t get really excited,” Evanoff recently recalled. “And all of a sudden, he stopped. He looked down and he started jumping around and I thought, hmm, Ken found something.”It was the tip of the frill of a remarkably intact horned dinosaur skull.
Carpenter recognized it from just the small bit of bone visible on the surface.“So we sat there for an hour or two just cleaning it up and getting exposed at the surface on that on that day,” Evanoff said.
The next day, they returned with a small crew and a truck to finish the excavation, prepare the skull for transport and haul it away. The specimen they eventually took out of the ground was about four feet long — small for a species with skulls that usually measure six to eight feet in length. They reasoned that it was from a juvenile animal and looked forward to getting it back to be lab for a closer look. In 1982, the Seven Cross Ranch was owned by Sonny Mapellli, a civic-minded former state senator and businessman.
According to his daughter, Terri DeMoney, Mapelli was usually magnanimous, but the way the paleontologists had handled the fossil rubbed him the wrong way.“They didn’t tell them that they were coming — that they found a dinosaur head. They just came back and took it. And when my dad heard what happened, he got in touch with them and he wanted it back,” DeMoney said.Mapelli took a lot of pride in his adopted Northern Colorado community.
So, when he found himself in possession of a significant piece of the area’s ancient prehistory on his hands, he decided to donate it to the local government.“He wanted it to stay here so that other children and families could all learn about it and actually have something here in Weld County,” DeMoney said.
As Sertich explains, “you look a little closer, you can tell from the texture of the bone that it is an adult.”And there was the Laramie rock formation that Pops came out of, which dates to 69 to 70 million years ago. That’s about 2 million years older than other known Triceratops specimens.
All of that raised doubts about Pop’s identity.“But no one’s had access to study because it was in this kind of gray area between museums and hiding up in a in a public facility,” Sertich said.In 2018, Sertich took advantage of his platform at the Denver Museum of Nature and Science. He reached out to Weld County officials with a proposition. He wanted the county to let him study Pops in Denver.
In return, he and his team would return the fossil to Weld County expertly cleaned and restored. County commissioners were excited. They struck a deal. Last fall, Sertich and his team made the trip up to Greeley to take measurements and plan out the transport. But he was also on a mission to solve a minor mystery.
The boxes contained pieces of bone that helped complete the skull. But there were other body parts, too: vertebrae and pieces of tail bone, for instance. Those body parts — now spread out across counters and carts in the fossil lab — can fill in some of the blanks in Pops’ story.