Paleontologists have described what they say is the first known trackway left by a walking adult Tyrannosaurus rex, a discovery that lets scientists reconstruct, for the first time, how fast one of the largest land predators in history actually moved.
The trackway, made up of four connected three-toed footprints, was found in the Hell Creek Formation of southwestern North Dakota, near the small town of Marmarth close to the Montana border, according to CBS News. The formation is one of the most productive fossil beds in North America for late Cretaceous dinosaurs, including T. rex itself.
A rare glimpse of movement, not just bone
The full trackway stretches about seven metres, with each footprint roughly a metre long. Researchers estimate the tracks are around 66.5 million years old, placing them near the very end of the dinosaurs’ reign before the mass extinction that followed.
Before this find, 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 any evidence that the animal had been moving. A connected sequence of prints is a different kind of evidence entirely.
Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior.
That assessment comes from Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science, who led the research team and grew up in the North Dakota badlands where the tracks were found. “With a trackway, we can actually follow an animal as it moved across the landscape,” he said, according to CBS News. “That is incredibly rare for T. rex.”
Calculating the speed of a seven-ton predator
By measuring the spacing between the footprints, the team estimated the animal was walking at roughly 5.6 to 7.2 km/h, a brisk human walking pace, despite weighing more than seven tons. Scientists attributed the tracks to an adult T. rex based on the footprints’ large size, their narrow three-toed shape, and the unusually high concentration of T. rex fossils already documented in the surrounding rock layer.
The footprint casts themselves are heavily fractured and preserve little fine anatomical detail beyond overall size and the number of toes, the peer-reviewed paper notes. Even so, the sequence was enough to support the speed calculation and the identification of the trackmaker.
The discovery was made in 2025 by Kent Hups, a high school teacher and volunteer fossil hunter, during a dig led by Lyson on land managed by the U.S. Forest Service. The findings were published in the Journal of Vertebrate Paleontology by a team that included researchers from the Denver Museum of Nature & Science and Liverpool John Moores University in England, giving the study a transatlantic authorship that spans both the fossil’s home region and a British research institution.
The find adds a rare behavioural data point to a species already among the most studied dinosaurs on record, offering a fleeting record not of what T. rex looked like, but of what it was doing on one particular day, tens of millions of years ago.
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