Much as a tree's rings can be read for information about its age and past environmental conditions, the rings and scars of fossilized bones can be interpreted to gain information about a dinosaur's age, health, and behavior. Unfortunately, understanding "dinosaur growth rings" is much more complicated than scanning the clockwork annual depositions of a redwood.
I love this kind of shit (excuse my French)! I also enjoy CSI, not the closeups of the gory details (my son digs that), but the lab analysis and chemical discussions, the physics of bullets etc. etc. This shouldn't come a surprise to anyone with a faint idea of who I am. Much in the same way this article about dinosaurs makes me happy. Talking about CSI stuff, apparently many of the dinosaurs are found in a peculiar position with their tail and head curled the wrong way. Still a mystery to the scientists who seem to have numerous more or less creative ideas of WHY we find the bones piled up in that particular position.
Great fun! :-)