Scientists investigated walking speeds, a possible family grouping, population numbers, and a large individual.
Not all tyrannosaurs were Tyrannosaurus rex. That animal was just the last and largest of a group of carnivorous dinosaurs that includes over two dozen species, some of which were no bigger than turkeys.
They first appeared in the middle of the Jurassic Period, around 161 million years ago, and culminated with Tyrannosaurus rex at the end of the Cretaceous Period 66 million years ago.
A site in southern Utah, discovered in 2014, contained the remains of four individuals of Teratophoneus curriei, a species of tyrannosaur that lived about 10 million years before Tyrannosaurus rex. Other fossils at the site included clams, fish, turtles and a young giant alligator. Over a thousand bones were mapped and collected.