A teacher recovering from knee-replacement surgery was picking his way out of a rocky North Dakota valley when a lumpy shape in the stone made him stop. The odd formation looked like three enormous toes. That chance discovery led researchers to a 23-foot line of giant fossil footprints that may be the first trackway left by an adult Tyrannosaurus rex.
Each footprint is roughly three feet long. The peer-reviewed study describes four prints in the measured sequence; National Geographic’s on-site account also describes a fifth mark as the team traced the path. Either way, this is more than a single suspicious dent in a rock. It is a short, physical record of a huge animal moving through the landscape about 66.5 million years ago.
A strange lump stopped Kent Hups in his tracks
Kent Hups, a Colorado high-school science teacher and longtime volunteer with the Denver Museum of Nature & Science, was prospecting for fossil sites in 2025. After a knee replacement, he was looking for an easier way out of a narrow, rocky valley in North Dakota’s Hell Creek Formation when he spotted the peculiar, three-toed shape.
Hups had spent decades thinking about ancient footprints, but even he needed a second opinion. He texted paleontologist Tyler Lyson, a museum curator and friend who was working nearby. Lyson was skeptical. A footprint can be altered by the animal’s movement, the softness of the ground and millions of years of erosion; it is not a fossilized foot with a name tag attached.
Then Lyson proposed a test. If Hups had found a trackway, another print should be at a particular spot. The team dug there and hit stone where Lyson predicted. That was the moment a peculiar shape began to look like a trail.
Four prints turn a footprint into a walk
The formal study, published in the Journal of Vertebrate Paleontology, describes a roughly 23-foot (seven-meter) trackway with four large, three-toed prints. The Denver Museum of Nature & Science’s project page gives the sequence as two left and two right footprints, each about three feet long.
There is a small counting wrinkle in the public record. The study and museum summary describe the four-print sequence used for the measurements. National Geographic’s field report describes the team finding a fifth footprint while following the line. That extra observation is worth mentioning, but it should not be silently folded into the paper’s four-track analysis.
The museum team used high-resolution 3D surface scanning to document the prints and the path between them. Those scans let researchers examine the worn surfaces from different angles and make physical reproductions. The fossil casts themselves are weathered, irregular masses of stone, not the clean, perfectly outlined impressions a movie might give you.
The trail gives paleontologists a rare movement clue
Isolated footprints can suggest the size and shape of an animal’s foot. A sequence adds something more: spacing. The distance between successive prints gives researchers a stride of about 13 feet. From the trackway’s dimensions, the team estimated a walking speed around 1.5 to 2 meters per second, or roughly 3.5 to 4.5 miles per hour—a brisk human walking pace.
That is an estimate, not a dinosaur speedometer reading. The tracks are heavily weathered, and the researchers note that speed calculations depend on assumptions about the animal’s leg length and how it moved. The useful payoff is more modest and more exciting: for once, scientists have a short sequence that can be studied as movement rather than one fossilized moment.
The setting helps explain why the find matters. Hell Creek is famous for dinosaur bones, but its ancient streams and swamps often erased tracks before they could be preserved. Bones record anatomy; tracks can preserve behavior. A trail this clear is an unusually good clue to how one large animal crossed its environment.
Why researchers say “likely” T. rex
The authors describe the trackway as likely attributable to an adult T. rex. The enormous size and narrow, three-toed form fit that interpretation, and T. rex fossils are abundant in the area. But tracks do not identify their maker as neatly as a labeled skeleton. The paper’s careful wording belongs in the headline and the story.
That caution does not drain the wonder out of it. The discovery is the first published sequence of tracks likely made by an adult T. rex, not the first dinosaur footprint ever found and not proof that every large three-toed track belonged to the famous tyrant. Earlier isolated tracks have been attributed to adult T. rex; what researchers lacked was a sequence showing the animal’s steps.
This is paleontology as a very patient detective story: a teacher notices a shape, a skeptical curator asks for another print, and a dig tests the prediction. The suspect has been gone for tens of millions of years. The evidence is a handful of weathered stones that still preserve the spacing of its walk.
See the real trackway
The museum’s short video shows the documented trackway and its 3D scanning work. It is a useful look at the actual fossil surface—the real payoff behind an illustration.
Sources: Falkingham et al., Journal of Vertebrate Paleontology, published September 8, 2026; Denver Museum of Nature & Science trackway project; National Geographic, September 8, 2026; Axios Denver, September 9, 2026.
Featured image: original editorial illustration based on the weathered, raised track casts shown in the Denver Museum of Nature & Science’s reference photographs. It is not a documentary excavation photograph.
