What was the lifespan of a dinosaur?

Factual Questions
1

I suppose it must have varied between species, but how would anybody figure that out anyway?
I imagine that sauropods, like elephants, would live a long time whereheas a deinonychus or an archaeopteryx’s time would be more limited.

2

Try this:

http://pubs.usgs.gov/gip/dinosaurs/lifespan.html

and

http://library.thinkquest.org/C005824/FAQ.html

basically they say anywhere between 50 and hundreds of years, depending of what kind of metabolism they had.

3

Short answer: No one knows.

Long answer: No one knows because there are many variables involved, chief among which is metabolic rate. While the jury is still out on this topic, more and more evidence points to endothermy. Unfortunately, even if we knew this, we still couldn’t do much more than guess. Few animals live to old age in the wild, so knowing a maximum life-span wouldn’t really do us much good. Beyond some basic generalizations, as the OP pointed out, we don’t have much to go on.

More than likely, like coloring, this may be an aspect of dinosaur biology we will never know about.

4

Funny, I didn’t even realize dinosaurs HAD crayons…

5

That’s because crayons don’t fossilize well. But most paleontologists agree that young dinosaurs probably would have gotten on their parents’ nerves (and most likely would have been eaten in order to shut them up) without some sort of activity to keep the younguns busy. Crayons seem like an obvious solution.