Sixty-six and a half million years after the last Tyrannosaurus rex walked the earth, a high school teacher in North Dakota looked down and saw what scientists had long searched for: the footprints of a giant, still mid-stride. Four fossilized tracks, pressed into what was once soft Cretaceous mud and now locked in stone within the Hell Creek Formation, constitute the first confirmed adult T. rex trackway ever documented — a sequence of steps that, for the first time, allows science to observe not just what this animal was, but how it moved through the world it ruled.