First Adult T. Rex Trackway Discovered in North Dakota

Paleontologists have identified the first-ever trackway of an adult Tyrannosaurus rex, a groundbreaking discovery that offers unprecedented insights into the behavior of the iconic dinosaur. The sequence of four giant, three-toed footprints, found preserved in mudstone, was discovered in 2025 on U.S. Forest Service land near Marmarth, North Dakota, an area rich in fossils. This remarkable find, dating back approximately 66.5 million years to the late Cretaceous period, is detailed in a new study published in the Journal of Vertebrate Paleontology.

The trackway, stretching about 23 feet, consists of two left and two right footprints, each roughly three feet in length. The stride between successive prints of the same foot is approximately 13 feet. Researchers from the Denver Museum of Nature & Science and Liverpool John Moores University used these measurements and locomotion equations to estimate the dinosaur's speed. They determined that the adult T. rex was walking at a brisk pace of 3.5 to 4.5 miles per hour, comparable to a brisk human walk. "With a trackway, we can actually follow an animal as it moved across the landscape," said Tyler Lyson, senior curator at the Denver Museum of Nature & Science. "That is incredibly rare for T. rex." This preserved moment captures the dinosaur in motion, offering a glimpse into its daily life.

Understanding Dinosaur Behavior Through Footprints

The attribution of these tracks to an adult T. rex is based on a process of elimination and the sheer scale of the prints. While isolated T. rex footprints have been identified before, a complete walking sequence that reveals stride and speed has never been definitively linked to an adult specimen. Previous trackways attributed to tyrannosaurs were found to be from juveniles or smaller related species. The immense size of these prints, the narrow angle between the toe impressions, and the abundance of adult T. rex bones in the surrounding geological formation leave no other plausible candidate.

The analysis of the trackway utilized modern technology, including high-resolution 3D surface scanning. Intriguingly, lead author Peter Falkingham, a renowned expert in dinosaur track analysis, examined the data remotely from his base in Liverpool, receiving scanned models from colleagues in North Dakota. This method allowed for detailed study of the prints, which are naturally preserved as hardened sandstone casts.

The initial discovery was reportedly made not by a professional paleontologist but by a high school teacher involved in the museum's field program. This highlights the significant role amateurs and educators play in paleontological discoveries. Plans are underway to airlift three of the four prints via helicopter this fall for installation at the Denver Museum of Nature & Science.

The scientific significance of this find lies not just in identifying the animal, but in understanding how it moved. For decades, scientists have debated the locomotion of T. rex, contrasting dramatic portrayals like those in *Jurassic Park* with biomechanical models suggesting a running T. rex would have required impossibly large leg muscles. The prevailing theories have leaned towards a T. rex that preferred walking, using its long legs for efficient rather than exceptionally fast movement. This trackway provides the first direct evidence from an adult specimen, confirming that the animal moved at a relaxed, walking pace, aligning with established biomechanical predictions. "Every skeleton is a death; a trackway is twenty-three feet of a Tuesday," the study notes, emphasizing the unique behavioral data a trackway provides. This discovery offers a concrete data point from the creature itself, revealing a moment of its passage across the ancient landscape.