Scientists discovered the first known series of footprints from an adult Tyrannosaurus rex in North Dakota. A schoolteacher who volunteers at a museum first found the site.
The trackway includes four large footprints with three toes each. Each footprint is about 3 feet long. These prints show how the famous dinosaur walked across the land 66.5 million years ago.
Researchers used 3D surface scanning to study the footprints. From these scans, scientists calculated that the T. rex walked at a speed of 3.5 to 4.5 miles per hour. This is about the same speed as a fast human walk.
Dinosaur bones show how animals looked, but footprints show how they moved and behaved. Later this year, a helicopter will move three of the footprints to a museum in Denver.