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Introduction to How do scientists determine the age of dinosaur bones?
When paleontologist Mary Schweitzer found soft tissue in a Tyrannosaurus rex fossil, her discovery raised an obvious question -- how the tissue could have survived so long?
Mark Wilson/Newsmakers/Getty Images The 67-million-year-old Tyrannosaurus rex skeleton known as Sue stands on display at Union Station on June 7, 2000, in Washington, D. Today's knowledge of fossil ages comes primarily from radiometric dating, also known as radioactive dating.
Radiometric dating relies on the properties of isotopes.
The bone was 68 million years old, and conventional wisdom about fossilization is that all soft tissue, from blood to brains, decomposes.