A team of paleontologists has documented the first known trackway made by a full-grown Tyrannosaurus rex in the badlands of southwestern North Dakota, providing an unprecedented window into how the apex predator moved across the ancient landscape.
The find — four three-toed footprints preserved in a sequence running about 23 feet — was discovered in 2025 on U.S. Forest Service land near Marmarth, according to a new paper published this week in the Journal of Vertebrate Paleontology. Each footprint measures roughly 3 feet long, and spacing between prints led researchers to estimate the animal was walking at about 3.5 to 4.5 mph, despite an estimated body mass exceeding seven tons.
Why this trackway matters
Footprints capture a moment of behavior that bones alone cannot, researchers said. Until now, only two isolated adult T. rex footprints had been confirmed anywhere in the world — one in New Mexico and one in Montana — and neither preserved a sequence of steps. The Marmarth site therefore represents the first time scientists have been able to follow an adult T. rex as it moved.
"Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior. With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T. rex," said Dr. Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science.
The trackway was found by Kent Hups, a high school teacher and amateur fossil hunter volunteering on a dig led by Lyson. Hups said the discovery was a reminder of how curiosity and careful observation can lead to scientific breakthroughs.
How the find was studied
Researchers from the Denver Museum of Nature & Science scanned the site in three dimensions. Lead author Peter Falkingham of Liverpool John Moores University analyzed the 3D data and wrote the paper without traveling to North Dakota in person. The research team attributed the tracks to T. rex based on the prints' size and shape, and because the surrounding rock has yielded an unusually high number of tyrannosaur bones.
The same badlands produced a juvenile tyrannosaur nicknamed "Teen Rex," discovered in 2022 by three boys on a family hike. The combination of body fossils and now a trackway strengthens the case that the area was frequented by tyrannosaurs across age groups.
Measurements at a glance
| Feature | Measurement |
|---|---|
| Trackway length | 23 feet |
| Individual footprint length | ~3 feet |
| Estimated walking speed | 3.5–4.5 mph |
| Year found | 2025 |
Local and scientific significance
For Marmarth and the broader region of southwestern North Dakota, the trackway highlights the scientific richness of the badlands and may attract further research and educational interest. For paleontology, the discovery supplies a rare behavioral dataset for one of the most studied dinosaurs.
- It is the first documented sequence of steps made by an adult T. rex anywhere in the world.
- The trackway complements previously found skeletal material from the same rock units, reinforcing local tyrannosaur presence.
- 3D scanning and remote analysis enabled international collaboration without immediate on-site travel by the paper's lead author.
Researchers caution that while trackways illuminate motion and behavior, they represent a single moment in time and must be interpreted carefully alongside skeletal evidence and geological context. Still, the Marmarth trace provides a rare chance to consider how a massive predator walked the same ground now visited by hikers and fossil enthusiasts.
As the paper circulates among specialists, the site will likely be subject to additional study and conservation planning. Because the discovery occurred on U.S. Forest Service land, officials and scientists will need to balance public interest, research needs and protection of the fragile fossil surface.
The Marmarth trackway adds to a growing body of finds from North Dakota's badlands that together are reshaping understanding of the state's ancient ecosystems. For now, the four three-toed prints stand as a direct, momentary trace of a creature that has captivated researchers and the public for generations.
