Yes, paleontologists have discovered that the bones of dinosaurs have growth rings similar to those found in the trunks of trees that possibly represent each year of a dinosaur’s growth. The ring features are very small; to see them, the bones have to be cut into thin sections and examined under a microscope using polarized light. These growth rings are known scientifically as lines of arrested growth (LAG). Although they are assumed to form at the rate of one ring per year, no one truly knows if this is correct. That’s because the distances between the growth rings between dinosaurs species vary greatly.

Using this technique, scientists have estimated the age of certain dinosaurs. For example, the bones of a ceratopsian dinosaur, Psittacosaurus, indicated that this particular animal was about 10 to 11 years old when it died; a second analyzed dinosaur, a Troodon, was three to five years old; the bones of a sauropod called Bothriospondylus showed it was 43 years old; a Massospondylus, a prosauropod, was 15 years old; and a ceratosaur called Syntarsus was seven years old.