yrannosaurus rex wasn’t always the king of the dinosaurs. Before they became towering predators, tyrannosaurs star
ted out much smaller, and a newly discovered fossil is helping fill the gap between those two extremes.
The fossil findings are detailed in a study published Thursday in Communications Biology.
The dinosaur fossil was found in Utah, where it lived 96 million years ago in a lush delta during the Cretaceous period. It’s been
named Moros intrepidus, which means “harbinger of doom.” The dinosaur lived at the end of th
e allosaurs’ reign at the top of the food chain and before Tyrannosaurus rex arrived.
It’s now the oldest tyrannosaur from the Cretaceous period found in North America.
Medium-size tyrannosaur fossils have been found from the Jur
assic period, about 150 million years ago. And then, about 81 million years ago during the
Cretaceous, tyrannosaurs grew into giant predators and replaced allosaurs as the top of the food chain.