Paleontologists uncover the first adult Tyrannosaurus rex trackway, its footprints each about a meter long

Paleontologists working in the badlands of southwestern North Dakota have identified a set of fossilized footprints as the first known walking sequence made by a fully grown Tyrannosaurus rex. The four prints, each roughly three feet long, were pressed into soft ground about 66.5 million years ago, in the final stretch of time before the asteroid impact that ended the age of dinosaurs. Isolated tyrannosaur tracks have turned up before, but never more than a single print attributed to an adult individual, so a connected sequence showing how one of these enormous predators actually moved across the landscape is unusually rare. The discovery gives researchers a physical record of behavior that skeletal remains alone cannot provide.

Four Prints Spanning a Twenty-Three-Foot Walk

The newly described trackway stretches roughly seven meters, or twenty-three feet, and consists of four large, three-toed footprints arranged as two lefts and two rights, forming a genuine walking sequence rather than a single isolated mark. Each print measures about one meter, or 3.3 feet, in length. It was found in 2025 in the Hell Creek Formation, a rock unit in southwestern North Dakota that preserves the last chapter of the Cretaceous period, dating to roughly 66.5 million years ago.

The Hell Creek Formation spans parts of Montana, North Dakota, South Dakota, and Wyoming and is one of the best-studied windows into North America’s ecosystems during the final years before the end-Cretaceous mass extinction. It has already produced numerous Tyrannosaurus rex skeletons, along with Triceratops, Edmontosaurus, and other dinosaurs that shared the same floodplain landscape.

Large Theropod Tracks Are Uncommon in the Hell Creek Formation

Large theropod footprints of any kind are scarce in the Hell Creek Formation, and multi-print trackways are rarer still. Isolated tracks previously linked to tyrannosaurs include one described from New Mexico in 1994 and another from Montana in 2008, but neither preserved more than a single footprint from what paleontologists believed was a fully grown animal. Other tyrannosaur trackways found in Canada and Wyoming were made by smaller animals, either juvenile Tyrannosaurus or related species that never reached adult size. That scarcity makes trace fossils, evidence of movement and behavior rather than bone itself, especially valuable whenever they surface.

Matching the Prints to an Adult Tyrannosaurus rex

Researchers based their identification on the sheer size of the footprints, the narrow angle between the toe impressions, and the abundance of Tyrannosaurus rex bones already recovered from the surrounding rock layers. No other large-bodied theropod known from the Hell Creek Formation reaches the size indicated by these footprints, which further narrows the likely trackmaker to an adult T. rex. The prints themselves survived in an unusual form, as hardened, calcium-carbonate-cemented sandstone casts that formed around the original depressions left in muddy overbank sediment.

Erosion later stripped away the softer surrounding rock, exposing the harder casts but leaving their surfaces heavily fractured, which limited how much fine anatomical detail remains beyond overall size and toe count. That combination of scale, shape, and geological context is what allowed the research team to move from “large theropod track” to a confident attribution to Tyrannosaurus rex specifically.

Estimating How Fast the Animal Was Walking

Using the spacing between the four prints, a stride of roughly four meters, or thirteen feet, researchers estimated the animal was moving at about 1.5 to 2 meters per second, or 3.4 to 4.5 miles per hour, despite weighing more than seven tons. That pace is consistent with walking speeds calculated from other large theropod trackways found elsewhere in the fossil record, reinforcing the idea that even the biggest tyrannosaurs moved at a measured, sustainable gait rather than a rapid run during ordinary locomotion. Paleontologists rely on this same stride-based method whenever only footprints, rather than a complete skeleton, survive to describe how an extinct animal actually moved.

A High School Teacher’s Chance Discovery

Kent Hups, a teacher at Northglenn High School, discovered the trackway in 2025 while working in the North Dakota badlands. Denver Museum of Nature and Science senior curator of vertebrate paleontology Tyler Lyson has noted that bones reveal a great deal about an animal’s anatomy, but footprints capture a single moment of behavior, letting researchers follow an individual as it actually moved across ancient terrain, something that is exceptionally rare for Tyrannosaurus rex.

The findings appear in the Journal of Vertebrate Paleontology, and were first reported this month as the first documented trackway attributable to a full-grown individual of the species, based on a study led by researcher Peter L. Falkingham and colleagues.

A Snapshot From the Final Years of the Cretaceous

The trackway dates to roughly 66.5 million years ago, placing it within a few hundred thousand years of the asteroid impact off the Yucatán Peninsula that ended the reign of non-avian dinosaurs. Every documented behavioral trace from this narrow window, including footprints such as these, offers a rare glimpse of a functioning Late Cretaceous ecosystem shortly before it disappeared. Because large theropod trackways are already uncommon in the Hell Creek Formation, researchers say future fieldwork in the same region could still turn up additional prints or even longer sequences from the same individual or others like it, adding further detail to how adult Tyrannosaurus rex moved through its environment day to day.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

More from Morning Overview