Asked by: Charlie Mack, Uckfield
Scientists can measure the age of some dinosaur species from the growth rings inside fossil bones, much as you can tell the age of a tree by the rings inside its trunk. The oldest known Tyrannosaurus rex specimen, this method tells us, was at least 30 when she died.
But this technique doesn’t work well on many species, because their bones grew continuously and don’t have neat growth rings. Early estimates of 300-year lifespans for the largest sauropods were based on comparisons with crocodiles and turtles, which have much slower metabolisms. The consensus is now that Apatosaurus and Diplodocus dinosaurs probably only lived for 70 or 80 years, which is about the same as an elephant today.