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How did scientists estimate the age of Tyrannosaurus rex from its bones?
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tyrannosaur
The fossilized remains of Sue, the most complete Tyrannosaurus rex skeleton in the world, on display at the Field Museum of Natural History, Chicago.
Scientists estimate the age of an individual Tyrannosaurus rex by examining its long bones, which contain annual growth rings similar to those found in trees. By counting these rings, researchers can determine the age of the dinosaur at the time of its death.1
By analyzing a series of bones representing various stages of development—from early growth to adulthood—paleontologists can reconstruct the life history of the species. These studies have revealed that T. rex typically reached its full adult size in less than 20 years. This method is distinct from radiometric dating, which is used to determine the geological age of fossils or rocks by measuring the decay of radioactive elements.12