A tyrannosaur is a type of large, meat-eating dinosaur that lived during the Cretaceous period, around 90 to 66 million years ago. The most famous tyrannosaur is Tyrannosaurus rex, or T. rex, which stood about 12 feet tall at the hip and stretched about 40 feet from nose to tail. These dinosaurs had massive heads with powerful jaws full of sharp, banana-sized teeth that could crush bone.

What made tyrannosaurs especially fearsome was their combination of size and hunting ability. They had surprisingly small arms compared to their enormous bodies, but scientists believe they used these arms for gripping prey or pushing themselves up from the ground. Their thick, muscular legs allowed them to move quickly for such large animals, possibly running up to 25 miles per hour in short bursts.

The name tyrannosaur comes from Greek words meaning “tyrant lizard,” which fits their role as apex predators, the top hunters in their ecosystem with no natural enemies. While T. rex gets most of the attention, the tyrannosaur family included other species like Albertosaurus and Tarbosaurus. These dinosaurs died out in the mass extinction event that ended the age of dinosaurs, the same event that wiped out about three quarters of all plant and animal species on Earth.