First adult Tyrannosaurus rex footprint trackway found in North Dakota

Discovery in the Hell Creek Formation

A team of paleontologists from the Denver Museum of Nature and Science in Colorado and Liverpool John Moores University in the United Kingdom has documented a fossil trackway left by an adult Tyrannosaurus rex. Identified in southwestern North Dakota near the town of Marmarth, the pathway extends across seven meters of the fossil-rich Hell Creek Formation. The trackway consists of four consecutive three-toed footprints, alternating between two left prints and two right prints. While researchers had previously documented isolated individual prints as well as tracks from juvenile specimens and closely related theropod species, this discovery represents the first known continuous series left by a walking adult T. rex. The findings, published in the Journal of Vertebrate Paleontology, date to approximately 66.5 million years ago. That timeframe places the dinosaur in North America relatively shortly before an asteroid impact ended the Cretaceous Period approximately 66 million years ago.

Biomechanical analysis and walking speed

Each fossilized footprint measures approximately 91 centimeters in length, recording strides of roughly 3.96 meters between consecutive steps. To examine the fragile imprints without damaging the rock bed, researchers conducted high-resolution 3D surface scanning across the seven-meter sequence. This scanning captured the physical shape, exact dimensions, and surface texture of the site, allowing the team to generate digital models and accurate physical replicas. Biomechanical calculations based on the stride measurements indicate that the adult dinosaur walked at a speed between 5.6 and 7.2 kilometers per hour, or 3.5 to 4.5 miles per hour. That rate is roughly comparable to a brisk human walk. Fossil evidence indicates that adult T. rex individuals stood between 3.6 and 4.0 meters tall and lived between 66 and 68 million years ago as among the last non-avian dinosaurs.

Insights into dinosaur behavior

Paleontologists emphasize that fossil trackways provide direct records of locomotion that skeletal remains cannot capture on their own. The continuous series of four prints allows researchers to reconstruct the exact gait and directional movement of the carnivore as it crossed the ancient landscape. Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature and Science, explained the scientific value of preserving real-time animal locomotion:

Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior. With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T rex.

Fieldwork and museum preservation

The fossil site was first discovered last year by Kent Hups, a Colorado schoolteacher and volunteer with the Denver museum who co-authored the research paper. Hups identified the impressions during field observations in southwestern North Dakota before bringing the location to the attention of professional paleontologists.

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.

Field teams plan to excavate three of the four fossilized footprints later this year. The selected track sections will be airlifted by helicopter out of the Hell Creek Formation to avoid ground transit damage across rugged terrain. Following the helicopter recovery, the specimens will be transferred to the Denver Museum of Nature and Science in Colorado for permanent curation, research access, and public exhibition.