Before Tyrannosaurus rex became the towering king of dinosaurs, its other tyrannosaur cousins were much smaller, roughly the size of a deer. The evolution of these smaller versions into T. rex is well documented in Asia, but in the North American fossil record, there’s been a 70-million-year gap in evolutionary records—until now.
Now, fossil evidence of a new tyrannosaur species closes that gap by about 15 million years. The new species is dubbed Moros intrepidus and it roamed what is now modern-day Utah about 96 million years ago, according to a new study published in Communications Biology. This pint-size T. rex predecessor—whose name is Greek for impending doom—might just help scientists understand how tyrannosaurs eventually rose to the top of the food chain in North America.