First Adult T. Rex Trackway Discovered in North Dakota

Scientists in North Dakota have unearthed what is believed to be the first known trackway, or sequence of footprints, left by an adult Tyrannosaurus rex. The discovery, made in the Hell Creek Formation of southwestern North Dakota on federal land, dates back approximately 66.5 million years. The findings were published on September 9 in the Journal of Vertebrate Paleontology.

The trackway stretches more than 23 feet and consists of at least four three-toed prints, each approximately 3 feet long. The immense size and narrow shape of the toes led researchers to conclude they were made by an adult T. rex. While isolated footprints attributed to adult T. rex have been found previously, this is the first time a continuous sequence of tracks has been described.

Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science and co-author of the study, recounted his initial skepticism when volunteer Kent Hups first discovered a print. "Initially I wasn't convinced because it was only one print," Lyson said, noting that rocks can erode into various shapes. However, upon finding a third print, which confirmed a pattern, he became a true believer.

The team excavated further, uncovering a total of five footprints. Using high-resolution 3D surface scanning, the prints and the entire trackway were meticulously documented. The researchers estimate that the dinosaur was walking at a pace of 3.5 to 4.5 miles per hour, comparable to human walking speed.

Three of the tracks are slated for recovery in October, with plans to airlift them out of the rugged Badlands. At the museum, efforts will be made to clean the tracks, with the hope that they might preserve skin impressions, which could provide a clearer understanding of a T. rex's foot anatomy. Lyson expressed confidence that further excavation could reveal additional tracks. "I have no doubt that if we were to continue to dig further into a hill that we would find more," he stated.

This discovery follows other significant paleontological finds, including a dinosaur trackway in Colorado from approximately 150 million years ago possibly left by a limping sauropod, and the identification of a new species of Spinosaurus in the Sahara Desert.