Tyrannosaurus rex may have been the fiercest dinosaur on the planet just before the creatures went extinct, but even T-rex had humble beginnings. A new fossil found in Utah shows that an earlier iteration of the behemoth stood just 3 feet to 4 feet tall and weighed about 170 pounds. A team led by North Carolina State University paleontologist Lindsay Zanno has dubbed this version Moros intrepidus, which means "harbinger of doom," reports CNN. The name is a nod to what the diminutive creature would evolve into millions of years down the road. Moros lived about 96 million years ago, preceding the dinosaur we know as T-rex by 30 million years, and the discovery may help shed light on the relatively scant fossil record of this particular evolution.
"When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time," says Zanno in a news release. "The only way to attack this problem was to get out there and find more data on these rare animals." Not that Moros was a complete wallflower: The discovered bones suggest it was extremely fast. "It could easily have run down prey, while avoiding confrontation with the top predators of the day," says Zanno. At some point, tyrannosaurs supplanted the gigantic allosaurs as the world's dominant dinosaur, but exactly when and why that happened remain mysteries, per the Atlantic. Only newly discovered fossils can help piece the puzzle together, and Moros is seen as a key first step. (Read more Tyrannosaurus rex stories.)