Researchers identify first known adult T. rex footprint trackway in North Dakota

Tracks suggest adult T. rex walked at brisk human pace

The first known series of footprints from an adult Tyrannosaurus rex has been identified in southwestern North Dakota’s Hell Creek Formation, a region long known for dinosaur fossils. Researchers from the Denver Museum of Nature and Science and Liverpool John Moores University in the UK first located the 23-foot trackway last year, and the findings have now been published in a scientific journal.

The trackway consists of four three-toed footprints — two left and two right — dating to approximately 66.5 million years ago, near the close of the Cretaceous Period. Each print is about 3 feet (0.91 meters) long, with a stride of about 13 feet (3.96 meters) from one footprint to the next. From those measurements, the research team estimated the animal was walking at roughly 3.5 to 4.5 miles per hour, comparable to a brisk human pace.

Isolated T. rex footprints and tracks from juveniles or related species have been documented before, but the team said this is the first known trackway left by a wandering adult of the species. The discovery offers paleontologists a behavioral record of a living animal that fossilized bones cannot capture.

Researchers used high-resolution 3D surface scanning to document each footprint and create physical 3D reproductions for further study. Three of the four discovered prints are scheduled to be recovered by helicopter later this year and transported to the Denver museum.

“Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior,” said Tyler Lyson, senior curator of vertebrate paleontology at the Denver museum. “With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T rex,” Lyson said.

According to the known fossil record, T. rex lived approximately 66 to 68 million years ago during the Cretaceous Period. The creatures stood 12 to 13 feet tall and were among the last non-avian dinosaurs to walk the Earth before the mass extinction event that ended the Cretaceous.

The discovery traces to a field encounter by Kent Hups, a Colorado schoolteacher and long-time museum volunteer who co-authored the paper. “As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation,” Hups said. “I never imagined that could lead me to a discovery like this.”