How long did dinosaurs live?

It is not possible to tell exactly what the normal life span of any dinosaur was. The main problem is that although dinosaur bones grow by adding layers on the outside, which means that they have growth rings that can be counted, the bones do not remain the same throughout their life. One dinosaur known as Massospondylus has been studied by Dr Chinsamy in Philadelphia and she suggested that it may have grown to an age of 70 years; this is however only one example.