Animal lifespans narrate in part to their body size and in part to their type of metabolism. Dinosaur lifespans almost certainly varied in length from tens of years to hundreds of years. Their probable maximum age can be estimated from the maximum lifespans of modern reptiles, such as the 66-year lifespan of the common alligator (Alligator mississippiensis) and the imposing lifespan of a Black Seychelles Tortoise (Geochelone (Aldabrachelys) sumeirei). One specimen of this now-extinct species, which was an adult when captured, lived a record 152 years in imprisonment (1766-1918) and had an accidental death. These estimates, based on lifespans of cold-blooded animals, would be too long if dinosaurs had metabolisms more alike to modern birds and mammals.
