T. rex lived in western North America about 69 to 66 million years ago, right at the end of the Late Cretaceous. It was one of the largest land predators ever known, with a massive skull, bone-crushing jaws, and a body built for power more than speed. Then, like Triceratops, it disappeared in the great extinction 66 million years ago, when the Chicxulub asteroid impact helped bring the age of non-avian dinosaurs to a close.

But T. rex was not the start of its story. Tyrannosaurs had already been around for more than 100 million years, beginning as much smaller hunters long before the giant late forms appeared. Early relatives such as Proceratosaurus and Guanlong were modest-sized predators, and over time the tyrannosaur line branched into forms like Dilong, Yutyrannus, Gorgosaurus, and Tarbosaurus before finally reaching the oversized late tyrants. So T. rex was not the first tyrant. It was the late, massive finale of a very long family history.

And even that bigger tyrannosaur story is only part of the wider predator story across dinosaur time. Before T. rex, other giant meat-eaters had already ruled different ages and continents: Jurassic hunters like Allosaurus, and later Cretaceous giants such as Spinosaurus, Carcharodontosaurus, and Giganotosaurus. In that larger frame, T. rex was not the only great predator of Dinosauria. It was one of the last and most famous, arriving late in a world that had already seen many different lines of giant hunters rise and fall.