The roughly 7-metre track line was found about 4 kilometres northwest of Marmarth. It contains two left and two right footprints and is considered the first consecutive trackway attributed to an adult T. rex; earlier discoveries were isolated prints rather than a sequence of steps.
The three-toed impressions measure about 90 centimetres to 1 metre long and 60 to 80 centimetres wide. The best-preserved print is 96 centimetres long and 80 centimetres wide. Their size and narrow toe shape, together with numerous T. rex fossils found in the area, support the researchers’ attribution.
The prints were not preserved in an ordinary mud layer. Sandstone formed around the depressions and hardened over time with calcium carbonate, making those sections more resistant than the surrounding rock. The impressions survived millions of years of erosion, and researchers documented the site with high-resolution 3D scans.
From the spacing of the four steps, the team estimated a hip height of about 4 metres and a pace of roughly 1.5 to 2 metres per second—consistent with walking, not running. The researchers stressed that the speed estimate is approximate. Rock-layer position and paleomagnetic data date the trackway to about 66.5 million years ago, near the end of the Cretaceous.