First Known Sequence of Adult T. rex Footprints Discovered in North Dakota

Paleontologists have discovered the first known sequence of multiple footprints attributed to an adult Tyrannosaurus rex. The tracks were found in the Hell Creek Formation near Marmarth, North Dakota, and are estimated to be 66.5 million years old. The find consists of four footprints, two left and two right, totaling seven meters in length. Each print measures approximately one meter long and between 60 and 80 centimeters wide.

Researchers from the Denver Museum of Nature and Science and John Moores University in Liverpool published their findings in the Journal of Vertebrate Paleontology. The team identified the tracks as belonging to an adult T. rex based on the tridactyl pattern, the size of the prints, and the prevalence of T. rex fossils in the region. They noted that other large herbivores, such as hadrosaurs, left wider toe prints. Based on the stride and size, scientists calculated the animal had a hip height of about four meters and was moving at a speed of 5.4 to 7.2 kilometers per hour, which is comparable to a brisk human walking pace.

The preservation of the tracks resulted from a specific geological process. The dinosaur left depressions in soft sediment that were filled with sandy material and solidified by carbonate rich groundwater. Subsequent erosion removed the surrounding softer rock to reveal the fossilized impressions. To analyze the site, the team used in situ digital scanning to create 3D images, allowing researchers to study the prints remotely.

While the reports are largely consistent in their scientific detail, there are slight differences in framing. The center lean outlet emphasizes the technological aspect of the discovery and the specific geological layers. The center left and center right lean outlets focus more on the behavioral insight provided by the tracks, quoting researchers on how footprints capture a moment of behavior that bones cannot.