First adult T. rex trackway discovered in North Dakota

Kent Hups, a high school teacher volunteering in North Dakota, discovered four giant dinosaur footprints that researchers believe represent the first trackway made by a full-grown Tyrannosaurus rex.

Hups found the unusual impressions in 2025 while working on a paleontological dig near Marmarth, North Dakota. The trackway, measuring about 23 feet long, includes two left and two right footprints, each roughly three feet in length.

Researchers published their findings in the Journal of Vertebrate Paleontology after examining the footprints’ size, shape, and location within the Hell Creek Formation, a region known for numerous T. rex fossils, including the skeletons of Sue and Stan. The area was once a swampy, forested floodplain, but footprints rarely survive there due to erosion. Scientists theorize that a unique combination of conditions preserved these tracks.

Bacteria-rich water filled the footprints, allowing minerals to accumulate and harden the impressions into dense casts. The team carefully removed three of the footprints, encasing them in plaster and burlap, to transport them to the Denver Museum of Nature & Science for further study. Researchers hope to use the tracks and digital 3D models to learn more about the dinosaur’s movement and foot structure.