T. rex Lived a Surprisingly Short Time
August 18, 2026
Ask someone to picture a dinosaur and they will probably picture Tyrannosaurus rex. Fair enough. What tends to get lost is the timescale. T. rex was not around for the whole Age of Dinosaurs. As a species, it lasted only about two million years, right at the end.
The Last Two Million Years of the Cretaceous
Every T. rex fossil we have comes from the late Maastrichtian, the final stage of the Cretaceous. The bones date to roughly 68 to 66 million years ago. Then the species vanished with the rest of the non-avian dinosaurs at the Chicxulub impact.
Two million years sounds long until you put it next to the rest of dinosaur history. The earliest dinosaurs show up in the Late Triassic, around 230 million years ago. Non-avian dinosaurs then occupied Earth for about 165 million years. T. rex sat in the last sliver of that span.
Non-avian dinosaurs lasted about 165 million years. T. rex occupied roughly the last 1 percent of that time.
A Short Species, Not a Short Animal
That two-million-year figure is the life of the species, not of one animal. Bone growth rings in skeletons like Sue, the famous T. rex in Chicago, put individual lifespan at around 20 to 30 years. Sue was about 28 when it died.
T. rex also was not a global animal. All confirmed fossils come from western North America, the island continent paleontologists call Laramidia. It was a late, regional predator that happened to become the face of an entire era.
Frequently Asked Questions
How long did T. rex exist as a species?
About two million years, from roughly 68 to 66 million years ago. That is the late Maastrichtian, the last stage of the Cretaceous.
How long did an individual T. rex live?
Growth studies of fossil bones suggest around 20 to 30 years. The well-studied skeleton Sue was about 28 years old at death.
Did T. rex live with most other famous dinosaurs?
No. It lived with animals like Triceratops and Edmontosaurus. It never met Stegosaurus, Diplodocus, or Allosaurus, which had been extinct for tens of millions of years.