Play Live Radio
Next Up:
0:00
0:00
0:00 0:00
Available On Air Stations
🐘 RNC updates via NPR: JD Vance is the headliner for night 3
Reporting from the St. George area focused on local government, public lands and the environment, indigenous issues and faith and spirituality.

Thanks to a Mesozoic hot spot near Moab, we finally know how old the Utahraptor is

Jim Kirkland, right, poses with other members of the Utah Geological Survey team in front of the giant block of Utahraptor fossils removed from the Stikes Quarry site near Moab.
Courtesy Utah Geological Survey
Jim Kirkland, right, poses with other members of the Utah Geological Survey team in front of the giant block of Utahraptor fossils removed from the Stikes Quarry site near Moab.

Sometimes Jim Kirkland wishes he had been alive 150 years ago.

That’s when the golden age of North American dinosaur discovery began, and early titans of paleontology crisscrossed the Rocky Mountains unearthing dozens of new species that became household names, from the Stegosaurus to the Brontosaurus to the Triceratops.

But a close second to that era is what Kirkland gets to see these days in Utah.

“I am doing that kind of discovery right now,” Kirkland said. “I’m just lucky to be alive.”

Kirkland, Utah’s state paleontologist, uncovered and named the Utahraptor in 1993. The deadly predator became the official state dinosaur in 2018.

Weighing more than 600 pounds, the Utahraptor used its nearly 10-inch claws to tear prey apart. These raptors were roughly the size of the clever villains depicted in the Jurassic Park movies — Velociraptors were actually closer to the size of a chicken.

Jim Kirkland holds the jaw fossil that led to his initial Utahraptor discovery in 1993.
Courtesy Utah Geological Survey
Jim Kirkland holds the jaw fossil that led to his initial Utahraptor discovery in 1993.

His latest discovery is part of a groundbreaking new study that establishes the Utahraptor’s absolute age for the first time. Thanks to samples from the Stikes Quarry site near Moab, scientists now believe the dinosaur is 135 million years old — 10 million years older than previously thought.

This research has implications beyond merely expanding our knowledge of Utah’s state dinosaur, he said. It changes the way scientists understand the grand chain of evolutionary history by closing a big gap in the fossil record.

“We’ve got a whole story here that didn't exist a few years ago,” Kirkland said. “Thirty-five million years of the history of Utah is just being unveiled in front of our eyes.”

Around the time the Jurassic period transitioned to the Cretaceous, there are roughly 25 million years missing in the fossil record. Nearly everywhere else on Earth — except this remote section of Utah — the rocks from that era simply washed away before compacting into sediments.

That left paleontologists guessing what happened during that time. Did animals slowly evolve into new species? Or did a mass extinction hit the reset button?

“No one would have the guts to say that because it was such a big gap. … But now we know this is total turnover,” Kirkland said. “For the first time, Grand County is going to be ground zero for looking at the extinction at the end of the Jurassic.”

This initial discovery, he said, might also eventually lead to some other answers, such as revealing new links in the family tree that connects dinosaurs to modern birds. And this pocket of southern Utah is the only place to find rocks from that time.

That’s thanks to the slow-moving salt deposits underneath the rock layers, which shaped the Earth’s crust in such a way that it kept the sediments from eroding away completely. It’s the same geological dynamic, he said, that gives the Moab area its famous arches.

And within that rare cluster of rock, Stikes Quarry is a dino bone gold mine. Kirkland describes it as a mass mortality site where Utahraptors got stuck in sinking pits of quicksand when they tried to attack plant-eating dinosaurs that were already trapped there.

Their rapid death and submersion left them exquisitely intact in a giant ball of fossils.

“What killed them is what buried them,” Kirkland said. “So they're perfectly preserved.”

Members of the Utah Geological Survey work on the Utahraptor mega block site at Stikes Quarry near Moab.
Courtesy Utah Geological Survey
Members of the Utah Geological Survey work on the Utahraptor mega block site at Stikes Quarry near Moab.

Over the course of a decade, the research team cut out a nine-ton block of rock packed with dozens of dinosaur skeletons.

The rare opportunity to see what’s under that block is what drew geologist Greg Ludvigson, emeritus senior scientist with the Kansas Geological Survey.

When Kirkland’s crew cut out that massive chunk, the spot where it was removed left something behind — an undisturbed, uneroded look into the rock layers from that era.

“It's something that's very special,” Ludvigson said. “It’s a little window into a period of time that we don't see elsewhere around North America.”

That’s where Ludvigson samples deposits to take back to his lab in Kansas and run a combination of two isotope dating techniques that hadn’t really been tried in tandem before: uranium-lead geochronology and radiocarbon dating with carbon-13 and carbon-12.

Kirkland had previously pegged the Utahraptor’s age at 125 million years by looking at the other animal fossils unearthed near these raptors and comparing them to other sites in the United Kingdom where those animals were found.

But Ludvigson’s isotope work found it to be a full 10 million years older.

A couple of other pieces of the study confirmed this finding through different avenues. One came from the plant record. The vegetation found at the Utahraptor site showed non-flowering plants instead of the blooming varieties that finally emerged around 125-115 million years ago.

The team’s work at Stikes Quarry also discovered the first North American record of the Weissert Event, a global catastrophe that resulted from the oceans going warm and stagnant roughly 133 million years ago, which further confirmed they were right about the Utahraptor’s age.

Part of the reason this study took so long, he said, was because they were basically paying for it themselves — working a couple of weeks per year whenever they could get there. The typical funders felt like the project’s untested methods were too much of a risk to put much money behind. But now that they’ve proven these types of radioactive dating techniques can work, Ludvigson said, it’s opening the door for future scientists to get funding for similar projects.

“It was a labor of love,” Ludvigson, who recently retired from the geological survey, said. “Careers don't last forever. When you look back at the end of it, what did you accomplish? This is something that we felt was important.”

Kansas geologist Greg Ludvigson examines an outcrop of colorful buried soils near Moab, Utah.
Courtesy Matt Joeckel
Kansas geologist Greg Ludvigson examines an outcrop of colorful buried soils near Moab, Utah.

In a broader sense, he said, this discovery further cements Utah as an epicenter for this type of paleontology and geology.

More of that attention will arrive June 8-10 when Kirkland and other members of the research team will present the findings at the Symposium on Mesozoic Terrestrial Ecosystems and Biota in Salt Lake City. It’s the first time this international conference of scientists will be held in the United States.

Southern Utah is rising to paleontological prominence now, Kirkland said, because there just weren’t many people digging around here until recently.

In other Western states like Wyoming, he said, many dino discoveries came in the late 1800s near transcontinental railroad lines that delivered visitors right into the middle of fossil-rich areas. But much of central and southern Utah remained difficult to access well into the 20th century — the Moab area’s only interstate highway wasn’t fully completed until 1990.

That kept Utah’s fossil secrets in the ground for a long time. Now, they’re beginning to come to the surface, and the world is noticing.

“Utah has the best record of the Mesozoic anywhere in the world, and now we're really starting to get international attention,” Kirkland said. “I just wish I had another 100 years to check this stuff out.”

David Condos is KUER’s southern Utah reporter based in St. George.
KUER is listener-supported public radio. Support this work by making a donation today.