jurassic start (wish i thought of this title myself)

Tyrannosaurus rex and its relatives were North America's dominant predators in the late Cretaceous period, about 99 million to 65 million years ago, but a new analysis of a toothy fossil skull suggests that the early history of this group includes smaller meat-eating ancestors that date as far back as 170 million years ago. Proceratosaurus now represents the oldest known relative of T. rex and its cousins, extending the evolutionary history of tyrannosaurs back to the middle of the Jurassic period. Proceratosaurus was bipedal and weighed between 28 and 36 kilograms—making it small compared with T. rex (which weighed about 8,000 kilograms) and most other Cretaceous tyrannosaurs. It probably measured about three meters long (only the skull is preserved, so the length is an estimate). Like other theropod dinosaurs, Proceratosaurus had four ferocious-looking and serrated snout teeth, D-shaped in cross-section. It also sported a nose horn.