Adult T. rex Leaves 4-Print Trackway in North Dakota After 66.5 Million Years

Q: Could these massive, weathered tracks actually belong to an unknown apex predator instead of a T. rex?

It is possible in theory, but the evidence points much more strongly to an adult *T. rex* than to an unknown predator. The case rests on several factors together, not on size alone. The prints are about 1 meter long, three-toed, and have the narrow toe shape expected of a large tyrannosaur. They come from the Hell Creek Formation, dated to about 66.5 million years ago, where *T. rex* is the best-known giant predator from the fossil record. Researchers also mapped a consecutive 7-meter trackway using high-resolution 3D scans, identifying a consistent left-right walking pattern from the same animal. The main reason for caution is the condition of the tracks. They are heavily weathered, and footprints are trace fossils, not bones. That means scientists cannot assign them with the same certainty as a skeleton. Speed and some fine anatomical details are therefore approximate. Even the team framed *T. rex* as the most likely trackmaker, rather than an absolute identification. Still, an unknown apex predator is not the leading explanation. For that to be more plausible, researchers would need independent evidence that another giant three-toed theropod lived in Hell Creek at that time. So far, the available fossil record does not show a better candidate. In short, paleontologists cannot rule out every alternative, but based on track shape, size, age, and location, *T. rex* remains by far the strongest identification.

3 articles · Updated · Sci.News · Sep 9

Four fossilized footprints, each about 1 meter long, were identified in North Dakota as the first trackway confidently tied to a full-grown Tyrannosaurus rex.
The 7-meter trail in the Hell Creek Formation dates to 66.5 million years ago, and its size, toe shape and the area's abundance of T. rex bones led researchers to the adult attribution.
A roughly 4-meter stride suggests the animal was walking at about 1.5 to 2 meters per second, giving paleontologists a rare snapshot of movement rather than anatomy alone.
The prints survived as calcium-carbonate-cemented sandstone casts after erosion stripped softer rock away, though that process left the surfaces fractured and short on fine detail.
Large theropod trackways are rare in Hell Creek, and earlier adult tyrannosaur finds in New Mexico and Montana were single prints, making this week's Journal of Vertebrate Paleontology report a notable behavioral record.