66.5 million years ago, a T. rex crossed North America; fossil footprints now show the giant dinosaur walked, not ran
For decades, paleontologists have studied Tyrannosaurus rex (T. rex) through bones, teeth and isolated footprints. Those fossils reveal what the animal looked like, how large it was and what it may have eaten, but they rarely show the creature in motion. That changed with the discovery of a short trail in southwestern North Dakota. Four…