A High School Teacher Found the First Adult T. Rex Footprints Ever Recorded

Footprints Frozen in Time

Somewhere in the rugged badlands of southwestern North Dakota, 66.5 million years ago, a fully grown Tyrannosaurus rex went for a walk. We know this now because a high school teacher happened to look down at the right moment. "As a teacher, I'm always telling my students that science starts with curiosity, passion and careful observation," said Kent Hups, a teacher at Northglenn High School who discovered the trackway. "I never imagined that could lead me to a discovery like this." His find has since rewritten the record books.

Paleontologists have confirmed the first known trackway made by a full-grown Tyrannosaurus rex: four connected footprints found in the badlands of southwestern North Dakota, not far from the Montana border. The find is described in a new paper published in the Journal of Vertebrate Paleontology. Before it, only two isolated adult T. rex footprints had ever been confirmed anywhere in the world — one in New Mexico and one in Montana — and neither showed how the animal was actually moving.

What Four Footprints Can Tell You

The approximately 23-foot-long trackway consists of four three-toed footprints, each roughly 3 feet long, and researchers estimate they were made about 66.5 million years ago. The sequence records two left and two right prints, with a stride of approximately 13 feet between them. That is a lot of ground covered per step — but then again, this was not a small animal.

Researchers used the spacing between the prints to estimate the animal was walking about 3.5 to 4.5 mph, despite weighing more than seven tons. That is roughly the pace of a brisk human jog — which is both reassuring and slightly terrifying to contemplate. "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."

Why This Spot Keeps Delivering

The trackway was found in 2025 on the Dakota Prairie Grasslands, managed by the U.S. Forest Service in Slope County. The tracks are preserved as fine-grained sandstone concretions cemented with calcium carbonate, which nucleated around the footprint depressions. Over time, erosion stripped away the softer surrounding rock, leaving the harder footprint casts exposed — though this process left the surfaces heavily fractured, and the prints retain little fine anatomical detail beyond their overall size and number of toes.

The team identified T. rex as the most likely trackmaker based on the footprints' exceptional size and narrow toe shape, along with the abundance of T. rex fossils found in the surrounding area. Other tyrannosaur trackways found in Canada and Wyoming measured about half this size, suggesting they belonged to younger or smaller relatives rather than a full-grown T. rex. This is also the same stretch of badlands where, in 2022, three boys on a family hike stumbled upon a juvenile T. rex fossil that researchers nicknamed "Teen Rex" — making this corner of North Dakota one of the most remarkable tyrannosaur sites on the planet.

What Comes Next

The site was scanned in 3D by Denver Museum researchers, and lead author Peter Falkingham of Liverpool John Moores University in England analyzed the data and wrote the paper without visiting North Dakota in person. That kind of remote collaboration, made possible by high-resolution scanning technology, is increasingly allowing scientists to study fragile fossil sites without risking damage to them.

Three of the footprints are expected to be recovered by helicopter this fall and then transported to the Denver Museum of Nature & Science, which plans to share updates from the recovery with guests this winter. For paleontologists, the bigger hope is that this discovery changes how researchers look at the landscape itself. Trackways are notoriously difficult to find — bones are far more common in the fossil record — but this find is proof that the ground beneath the badlands still holds secrets worth chasing.