Paleontologists have documented the first known adult Tyrannosaurus rex trackway in North Dakota, revealing a 23-foot sequence of four fossilized footprints that sheds rare behavioral light on how the seven-ton predator walked roughly tens of millions of years ago.
For decades, our understanding of the king of the tyrant lizards came almost entirely from its bones. Skeletal remains tell researchers a great deal about anatomy, bite force, and evolutionary lineage, but they reveal little about how a living animal moved across an ancient landscape. That longstanding gap in the fossil record shifted when a volunteer discovered a continuous line of fossilized footprints in the badlands of southwestern North Dakota.
A High School Teacher’s Discovery in North Dakota
The site sits on federal land managed by the U.S. Forest Service near the small town of Marmarth. In 2025, Kent Hups, a high school teacher and longtime amateur fossil hunter volunteering on a dig, spotted an unusual rock. Over the following days, Hups uncovered three more, forming a continuous line that would eventually make him a co-author on the scientific paper describing the find.
The discovery was detailed in a paper published in the Journal of Vertebrate Paleontology. The research was led by Peter L. Falkingham of Liverpool John Moores University alongside a team from the Denver Museum of Nature & Science. Prior to this find, paleontologists had confirmed only two isolated adult T. rex footprints anywhere in the world—one in New Mexico and one in Montana. Each of those earlier prints captured a single isolated instant, offering no way to determine how the animal traveled.
Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum and a study co-author, emphasized the rarity of the find. As Lyson noted, bones describe anatomy, but a trackway lets researchers follow an animal as it moved through the landscape.
Mapping a Seven-Ton Predator at Walking Pace
The published trackway spans roughly 23 feet, or 7 meters, in length. It consists of four three-toed, or tridactyl, footprints. Each print measures about 3 feet, or 90 centimeters, long—larger than an adult human’s forearm-to-fingertip reach. The sequence is arranged as two left steps and two right steps, separated by roughly 13 feet, or 4 meters.
Using the precise spacing between the prints, researchers calculated a walking speed of roughly 5.6 to 7.2 kilometers per hour, translating to 3.5 to 4.5 miles per hour. That speed roughly matches the pace of a brisk human walk, achieved by an animal weighing more than seven tons—equivalent to the combined weight of two full-grown African elephants.
Two distinct lines of evidence led researchers to attribute the trackway specifically to Tyrannosaurus rex rather than another large predator. First is the sheer scale of the impressions, which dwarf any other theropod track known from the location. Second is the morphology: the toes are narrow and elongated, matching the foot skeleton of T. rex specifically.
Field Scanning and High-Resolution 3D Analysis
Because of the fragility and weathering of the badlands site, documenting the prints required advanced digital tools. Denver Museum researcher Evan Tamez-Galvan, working under Lyson’s direction alongside museum colleague Antoine Bercovici, documented the trackway with high-resolution 3D scanning in the field.
This digital preservation allowed the team to analyze the geometry of the prints in the lab. While tens of millions of years of erosion have blurred the original depth and edges of the tracks, the digital models provided a clear view of stride length, step angles, and external trackway width.
Broader Behavioral Insights from Ancient Trackways
The North Dakota discovery mirrors advances in how paleontologists study other ancient movement patterns. Earlier research into a rare looping trail of fossilized footprints in Colorado demonstrated how modern imaging technologies extract behavioral details from long track sites. In that 150-million-year-old site near Ouray, Dr. Anthony Romilio of The University of Queensland’s Dinosaur Lab and Dr. Paul Murphey of the San Diego Natural History Museum used drones to map more than 130 footprints.
“It has been challenging to document these footprints from the ground because of the size of the trackway. We used drones to capture the entire trackway in high resolution.”
Dr. Paul Murphey, San Diego Natural History Museum
By combining drone photography with 3D models, researchers studying both the Colorado sauropod site and the North Dakota theropod tracks are uncovering how giant dinosaurs handled turning, variations in stride length, and subtle shifts in gait.
Uncertainty and Future Preservation
Despite the high-resolution data, researchers remain transparent about the limitations inherent in ichnology—the study of fossilized tracks. Without a matching skeleton resting directly inside the footprints, a small margin of uncertainty remains in species attribution.
Yet, the surrounding geological context heavily reinforces the conclusion. The rock strata near Marmarth have produced an unusually high concentration of tyrannosaur bones, including a well-known juvenile specimen nicknamed Teen Rex
that was also excavated by Lyson’s team. As ongoing erosion exposes more of the federal land, paleontologists anticipate that similar non-destructive imaging techniques will help unlock behavioral data from other ancient trackways around the world.
