Live fast, die young: How dinosaurs lived viciously short lives

It used to be thought that many dinosaurs achieved such huge sizes because they grew slowly and continuously, like crocodiles and iguanas do, for a century or more. We now know this wasn’t the case, and that dinosaurs generally grew fast and died fairly young.

We can tell the age of dinosaur fossils by cutting open their bones and counting growth lines; that’s because, similar to a tree, dinosaurs laid down one ring of bone growth every year. This technique tells us that Tyrannosaurus rex reached full size in about 16 to 22 years, and usually died at 27 to 33 years old.

Other big carnivores called Carcharodontosaurids lived to between 39 and 53 years old. The very largest dinosaurs, the long-necked sauropods like Brontosaurus and Diplodocus, seemed to have reached a similar age, although some could have lived maybe a decade or two longer – perhaps up to 70 years old.

Read more:

• What was the first dinosaur?
• How did dinosaurs mate?
• How long did it take dinosaur eggs to hatch?
• How did dinosaurs sleep?

Asked by: Alex Carlson, via email

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