The discovery of a new species of tyrannosaur will help scientists understand how its famous cousin the Tyrannosaurus rex evolved.
A fossil of the four foot tall Moros Intrepidus (which means harbinger of doom) was found in Utah National Geographic reports.
Despite its relatively diminutive size, the tyrannosaur that roamed the earth 100 million years ago was still extremely lethal.
"Moros was lightweight and exceptionally fast. These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator.
"It could easily have run down prey, while avoiding confrontation with the top predators of the day," North Carolina State University paleontologist Lindsay Zanno said.
Scientists believe the dinosaur weighed around 78 kilos and and reached maturity at between six and seven years of age.