Crocodiles can have extra growth cycles in a year: Why this matters for estimating the age of dinosaurs‎

In biology and paleontology (the study of extinct organisms) there are a few ways to estimate the age of an animal's skeleton. One is the extent of fusion of sutures in the skeleton—how much the plates of bone have joined together as the animal matured. Another is the texture of the bone surfaces. Then there are growth marks recorded in the microscopic structure of bone.