In biology and palaeontology (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.
Many modern animals grow in periodic spurts (fast at times, slowly at other times). It’s generally thought that they grow fast in the good seasons when the environment is better for them in terms of food, temperature and water. They are thought to grow more slowly during unfavourable seasons, when the growth marks form in their bones, rather like the rings formed in trees. By counting the number of growth marks inside the bone tissues, scientists estimate the age of the animal. This method is called skeletochronology.
Over the years there have been a few studies that have determined when the different growth cycles formed, and have proposed the utility of skeletochronology for age determination.
