[CoreSet]

What about if dinosaurs got to the point of early hunter-gatherers - establishing communities, language, basic tools - but were then wiped out?

It's different from the case he cites, but tracks the general point that there are limits to what we can learn about prehistory / "deep time"

[Udik]

If we can find their fossilized skeletons, can't we find their stone tools? Maybe scattered around their ritual burials?

[api]

Think of it this way: distance in time is like distance in space. It's just another dimension (with the catch that apparently we can't actually move backward). The dinosaurs are as far from us as Alpha Centauri, maybe further.

[jerf]

This is a reasonable way of looking at time for certain purposes, and the conversion factor is c. So, 65 million years "ago" is also 65 million light-years "away" in the -t direction.