Four fossilized footprints are helping scientists step into a dinosaur’s shoes. The prints form the first known set of tracks likely left by an adult Tyrannosaurus rex.
A trackway is three or more consecutive footprints left by some animal. The one for this T. rex spans 7 meters (10 feet). The track spacing suggests the ancient predator had been ambling along at about 1.6 meters (5.2 feet) per second, which would be a quick walking pace for us.
A few single adult T. rex footprints have been recorded. So have trackways from what might be T. rex juveniles or another related species, says Peter Falkingham. He’s a paleontologist at Liverpool John Moores University in England.
Let’s learn about trace fossils
“Finding an adult trackway is cool,” he says. “It’s unique. It brings something new.”
The reason: “An individual [footprint] doesn’t tell you a lot,” Falkingham explains. “A trackway tells you more about foot placement as the animal’s moving along.” And younger and older dinosaurs likely walked differently, just as human toddlers and adults do.
Kent Hups teaches at Northglenn High School, outside Denver, Colo. (A paleontologist, he also works at the Denver Museum of Nature and Science.) Hups stumbled on the trackway while fossil hunting in North Dakota last year. It stuck up out of the ground along a steep incline in the Hell Creek Formation. Sediment had filled in the originally muddy footprints and fossilized. It then eroded away more slowly than the surrounding rock.
The first print that he found was three-toed and enormous. It measured 80 centimeters (31.5 inches) across. He recalls immediately thinking: “This has to be a T. rex.”
Four Tyrannosaurus rex footprints are seen from above in a drone photo (left). They make up the first discovered trackway found from an adult of this species. The frontmost print (right) is the best preserved and displays three distinct toes. K. Hups
Slender toe impressions and fossils unearthed in the area signal the trackway had been left behind roughly 66.5 million years ago. “There’s always the possibility that we haven’t found the skeletons of some species that we don’t know about,” Falkingham says. “But as far as our knowledge goes, T. rex is about the only track-maker that could have made these.”
He and Hups were part of a team that used stride length and body size to gauge the dinosaur’s speed. Unfortunately, the footprints aren’t well-preserved. And estimating speed from tracks is tricky. So the T. rex may have been walking slightly faster or slower than what they reported September 8 in the Journal of Vertebrate Paleontology.
Better tracks could have revealed whether the foot landed flat or toe-to-heel — or even how its foot pads supported the dino’s weight.
More tracks are sure to follow. In fact, a fifth step may be concealed in the hill. But the team is waiting for Mother Nature to wear away the surrounding rock, Hups says. “I can’t wait to get back out there and keep looking for more.”
Bengali (Bangladesh) · 
English (United States) ·