How long did a t-rex live?

The species survived for only a few million years. Individuals have been found as old as 28 years and that is estimated to be near the maximum age of a T. rex.

The Tyrannosaurus rex lived during the the Maastrichtian age of the upper Cretaceous period and estimated 65 to 70 million years ago. It lived throughout what is now western North America. Geological records only exist for a time span of about 5 million years. T. rex ended its existence at the time of the Cretaceous–Paleogene extinction event 65-66 million years ago.