Kent Hups, a high school science teacher in Colorado, discovered a 23-foot trackway of fossilized Tyrannosaurus rex footprints while volunteering on a dig in the North Dakota badlands near Marmarth, N.D. Recovering from knee replacement surgery, Hups was walking flatter routes in the Hell Creek Formation when he spotted a lumpy triangle of sandstone resembling giant toes. Measurements confirmed it was only the third adult T. rex track ever found and the first confirmed walking trackway of a fully grown specimen.

The trackway, found in July 2025 on U.S. Forest Service land, consists of four massive three-toed prints — each three feet long and two feet wide — showing a 13-foot stride. Researchers estimate the prints were made 66.5 million years ago near a riverbank and indicate the animal walked at 3.5 to 4.5 miles per hour. The findings were published in the Journal of Vertebrate Paleontology.

Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature and Science and excavation leader, was initially skeptical but confirmed the identification based on the prints' size, narrow toe shape, and abundant T. rex fossils nearby. Paleontologist Thomas Carr of Carthage College noted the rarity, stating that in over 120 years of Hell Creek exploration, this is the first such trackway. The prints are preserved as fine-grained sandstone concretions cemented with calcium carbonate.