Researchers have identified the first known adult Tyrannosaurus rex trackway, discovering four 66.5-million-year-old footprints near Marmarth, North Dakota. The 23-foot sequence reveals a 13-foot stride, showing the seven-ton apex predator maintained an unhurried walking pace of 3.5 to 4.5 miles per hour shortly before its species vanished.
Tracking a Seven-Ton Stroll in the Badlands
Paleontologists own thousands of Tyrannosaurus rex bones and dozens of skeletons, but until now, they lacked a recorded walk. Researchers from the Denver Museum of Nature & Science and Liverpool John Moores University documented four enormous three-toed footprints preserved in what was once Hell Creek mud (Space Daily). Found on U.S. Forest Service land near Marmarth in southwestern North Dakota, the sequence consists of two left and two right impressions left roughly 66.5 million years ago (The Guardian).
While isolated single prints credited to adult T. rex had been spotted previously, and smaller trackways attributed to juveniles or related species had been found in Canada and Wyoming, this discovery marks the first time science has captured a continuous walking sequence for a mature adult (Space Daily).
Tyler Lyson, senior curator at the Denver Museum of Nature & Science, noted that while bones provide anatomy, a trackway represents behavior.
“With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T. rex.”
Tyler Lyson, senior curator
Measuring the Pace of a Cretaceous Predator
The trackway stretches approximately 23 feet, with each individual footprint measuring roughly three feet long. By feeding the footprint size and the measured 13-foot stride—the distance between successive prints of the same foot—into standard locomotion equations, researchers calculated that the dinosaur traveled at a speed of about 3.5 to 4.5 miles per hour (Space Daily).
That velocity matches the pace of a brisk human walk. Scientists note that while the prints are heavily weathered, the calculated speed aligns with biomechanical models suggesting a walking adult preferred an unhurried gait (Space Daily). The attribution relies on elimination: the sheer size of the tracks, the narrow angle between the toe impressions, and the abundance of adult T. rex bones in the surrounding Hell Creek formation leave no other known animal matching the prints (Space Daily).
High-School Teacher Sparks a Paleontological Breakthrough
The initial discovery in 2025 came from Kent Hups, a high-school teacher and longtime museum volunteer working with the Denver institution’s field program (The Guardian). Hups later co-authored the formal study published in the Journal of Vertebrate Paleontology (Space Daily).
Hups, who often tells his students that science begins with passion, curiosity, and careful observation, said he never imagined those principles would lead him to such a discovery.
To analyze the find, the field team deployed high-resolution 3D surface scanning to document the impressions. This digital precision allowed lead author and dinosaur-track expert Peter Falkingham at Liverpool John Moores University to examine the trackway remotely using digital models sent from North Dakota, sparing him an in-person trip to the badlands (Space Daily).
Helicopter Recovery and Museum Plans
The prints themselves are preserved in an unusual medium as hardened, calcium-carbonate-cemented sandstone casts that act as natural sculptures of the original mud impressions (Space Daily). Museum plans involve airlifting three of the four discovered footprints out of the field by helicopter (The Guardian) for permanent installation at the Denver Museum of Nature & Science (Space Daily).
