Paleontologists in North Dakota have unearthed a 66.5-million-year-old trackway of four giant footprints left by a fully grown Tyrannosaurus rex. Published in the Journal of Vertebrate Paleontology, the discovery offers rare physical evidence of adult dinosaur movement.
For decades, our understanding of Tyrannosaurus rex has relied almost exclusively on bones, skulls, teeth, and skeletons assembled in museums. While skeletal remains reveal the anatomy and potential diet of the massive predator, they leave questions about how the animal actually moved across its prehistoric environment. Now, the discovery of a continuous trail of four massive footprints in southwestern North Dakota’s Hell Creek Formation provides the first direct physical evidence of walking behavior in a fully grown adult T. rex.
Discovery in the Badlands of North Dakota
The site was initially spotted in 2025 by Kent Hups, a high school science teacher and amateur fossil hunter based in Northglenn, Colorado, while he was volunteering on a dig led by Tyler Lyson, senior curator of vertebrate palaeontology at the Denver Museum of Nature & Science. Operating on federal land administered by the U.S. Forest Service near Marmarth, North Dakota, Hups noticed a lumpy, wedge-shaped protrusion sticking out of the ground.
Although Lyson was initially skeptical—given that only two isolated adult T. rex footprints had ever been documented worldwide, with one in New Mexico and another in Montana—the team returned the next day to investigate. They uncovered a continuous trackway measuring roughly 23 feet long. The line features two left and two right footprints, with each print measuring about 3 feet long and featuring a stride length of approximately 13 feet.
“As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation. I never imagined that could lead me to a discovery like this.”
Kent Hups, high school teacher and amateur fossil hunter
Unique Preservation in the Hell Creek Formation
While dinosaur bones are relatively common in the Hell Creek Formation—a 66- to 68-million-year-old geologic layer spanning eastern Montana, the Dakotas, and Wyoming—large theropod trackways are exceptionally rare.
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Researchers suggest a distinct sequence of conditions preserved the stroll. Calcium carbonate and sandstone cemented into a dense mass harder than the surrounding mud. Over millions of years, erosion wore away the softer material, leaving the tracks exposed as raised, three-dimensional casts rather than hollow molds.
Speed Estimates and Digital Analysis
To study the delicate impressions without causing damage, the research team deployed high-resolution 3D surface scanning in the field. This digital data allowed scientists to visualize the tracks remotely in virtual reality and analyze the stride.
“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 visualise 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 and lead author of the study
Based on the spacing between the prints, researchers estimate the dinosaur was moving at roughly 3.4 to 4.5 miles per hour. This indicates that despite its formidable reputation, the animal was maintaining a brisk, walking pace rather than sprinting across the ancient landscape.
Broader Context of Hell Creek Discoveries
Unlike isolated bones or commercial specimens, however, the new trackway captures a fleeting moment of behavior.