Paleontologists have discovered the first known adult Tyrannosaurus rex trackway in the North Dakota badlands, consisting of four connected footprints dating back 66.5 million years. The 23-foot sequence reveals the apex predator walked at a brisk 3.5 to 4.5 mph stride just before the Cretaceous extinction.
For decades, paleontology has possessed thousands of bones and dozens of skeletons, but a recorded walk remained elusive. That changed when researchers from the Denver Museum of Nature & Science and Liverpool John Moores University announced the first-ever adult Tyrannosaurus rex trackway discovered in the badlands of southwestern North Dakota, not far from the Montana border.
Uncovering the Marmarth Trackway
The 23-foot sequence comprises four three-toed footprints—two left and two right—pressed into what was once Hell Creek mud about 66.5 million years ago, near the very end of the Cretaceous period. Kent Hups, a high school teacher and amateur fossil hunter volunteering on a Denver Museum dig, originally spotted the site in 2025 on U.S. Forest Service land near Marmarth, North Dakota.
“As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation,” Hups said. “I never imagined that could lead me to a discovery like this.”
Kent Hups, high school teacher and amateur fossil hunter
While isolated adult prints had been documented previously in New Mexico and Montana, none showed how the animal moved across the landscape. Previous track discoveries in Canada and Wyoming were attributed exclusively to juveniles or smaller related species.
Locomotion and the Seven-Ton Stride
Each footprint spans roughly 3 feet long. By feeding the footprint size and the roughly 13-foot stride gap into standard locomotion equations, researchers estimated that the animal walked at a speed of about 3.5 to 4.5 mph—matching the pace of a brisk human walk despite weighing more than seven tons.
“Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior,” said Dr. Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science. “With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T. rex.”
Dr. Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science
This pedestrian pace provides empirical weight to long-standing biomechanical debates. While cinematic portrayals often featured sprinting predators, modern scientific consensus suggested a walking gait optimized for efficient long-distance travel. The North Dakota trackway offers the first direct behavioral data confirming that prediction.
Digital Analysis and Field Recovery
The prints are preserved as hardened, calcium-carbonate-cemented sandstone casts. To study them without damaging the geological context, the field team documented every impression using high-resolution 3D surface scanning.
This technology allowed lead author Peter Falkingham of Liverpool John Moores University to analyze the site remotely. According to the study published in the Journal of Vertebrate Paleontology, colleagues scanned the stones in the badlands and transmitted the digital data to England.
“The technology we’re able to apply in the digital age means my colleagues could scan the tracks in the field and then send the 3D information over to me to visualize on my computer and in VR, enabling me to take as close a look as they did in person.”
Peter Falkingham, professor of paleobiology at Liverpool John Moores University
Next Steps for the Fossil Site
Researchers reinforced their attribution by pointing out that the surrounding rock formation has produced an unusually high concentration of tyrannosaur bones, including a juvenile specimen nicknamed Teen Rex
discovered nearby in 2022 by three boys on a family hike. Three of the four footprints from the newly described trackway are scheduled to be airlifted out by helicopter to be permanently housed at the Denver Museum of Nature & Science.
