Tyrannosaurus rex fossils are relatively common finds, with dozens of variously complete examples on display in museums around the world. But T. rex tracks? That’s an entirely different story. Even when stomped into the mud by a 17,500-pound apex predator, dinosaur footprints rarely last long enough to fossilize over millions of years.

That’s what makes a recent discovery in southwestern North Dakota so remarkable. Paleontologists from the Denver Museum of Nature & Science and Liverpool John Moores University in England have documented not one, but four footprints preserved along a 23-foot-long path within the famous Hell Creek Formation. The prints are the first known trackway made by an adult T. rex, and are described in a study recently published in the Journal of Vertebrate Paleontology.

While rare, T. rex footprints are distinctive for their massive size and narrow toes. In this case, each dino-stomp measures about three feet long. Paleontologists identified the roughly 66.5-million-year-old path last year on federal land near the town of Marmath, North Dakota, near the state’s southwestern border with Montana. After carefully clearing the surroundings, researchers imaged each footprint using a high-resolution 3D surface scanner. This allowed the team to digitally analyze the scene, as well as create physical reproductions.

The two left and right imprints suggest that the dinosaur was a sizable adult with an estimated 13-foot stride—but paleontologists don’t think this particular T. rex was in much of a hurry. Based on the gait, it was likely moseying around at 3.5 to 4.5 miles per hour, or about the same speed as a human going on a power-walk. Given the tracks’ weathering and erosion, the team stresses their theorized speed is somewhat speculative.

Paleontologists are now planning to excavate three of the four footprints later this year, then transfer them by helicopter to the Denver Museum of Nature & Science.

“Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior. With a trackway, we can actually follow an animal as it moved across the landscape,” Tyler Lyson, a Denver Museum of Nature & Science paleontologist and study co-author, said in a statement. “That is incredibly rare for T. rex.”

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Before 2025, paleontologists had confirmed exactly two footprints anywhere in the world made by an adult Tyrannosaurus rex — one in New Mexico, one in Montana. Isolated prints, each capturing a single instant, with no way to tell how the animal that made them actually moved. That changed with a discovery in the badlands of […]

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The largest Tyrannosaurus rex fossils ever discovered belong to a 66-million-year-old apex predator named Scotty. Like many T. rex skeletons, it’s difficult to determine if the specimen was male or female, but Scotty was an unequivocal bruiser. Standing 13-feet-tall at the hip and measuring upwards of 43-feet-long, the Late Cretaceous hunter weighed as much as 19,500 pounds.

However, Scotty isn’t simply the biggest T. rex on record. One of its bones still has traces of preserved soft tissue. This is almost never seen in paleontology, as soft tissues degrade due to the ravages of time. The only way to safely examine these delicate remains is through highly sensitive techniques like neutron imaging. But with the help of researchers at the Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) in Tennessee, paleontologists recently glimpsed Scotty’s rib and its remaining tissue in unprecedented detail. The results offer some of the first in-depth looks at fossilized dinosaur tissue on a microscopic level.

“It’s like winning the lottery,” Mauricio Barbi, a physicist at the University of Regina (U of R) in Saskatchewan, Canada, said in a recent interview. “Scotty’s rib contains a vast network of mineralized blood vessels that has never before been observed in a fossil.”

The reason for the blood vessels’ preservation is also a window into the T. rex’s death. The broken rib indicates that Scotty likely succumbed to injuries sustained during a dinosaur brawl. After the rib cracked, iron-saturated blood covered the wound and formed tiny blood vessels to facilitate faster healing. The anatomical response wasn’t enough, and Scotty soon died in a salty marsh. The surrounding environment slowed down the T. rex’s decomposition so much that it allowed many of those blood vessels to fossilize. 

To get a closer look at these details, paleontologists relied on neutron imaging to see the lighter elements present in the fossils as well as X-ray imaging to look at the heavier ones. From there, researchers also used synchrotron radiation and other microscopy approaches to analyze the healing tissues on a cellular level. Importantly, all of this imaging was possible without damaging Scotty’s priceless fossils.

“Neutrons not only corroborated what we found with synchrotron radiation techniques that led to the discovery of blood vessels in Scotty’s rib,” explained U of R physicist Marcella Berg. “They also proved to be a highly valuable addition to our current studies in search of soft tissue preservation in fossils.”

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