"The Earth has no memory for the dead-ends of evolution. In a few hundred thousand years glaciers would grind our works and our bones into gravel, would grind the gravel into sand, and in a few hundred million years the movement of continents erase the last of any trace of our brief existence, save perhaps for a handful of deeply-buried and enigmatic fossils."

This brings up a question I have often wondered about: do we really know we are the first intelligent conceptual life to do things like use tools and language on this planet?

If let's say a dinosaur reached the level of stone or bronze age civilization would anything be left other than... well... a couple enigmatic fossils that are easy to dismiss?

I doubt a massive high tech civilization like ours could come and go and leave no trace, but what about something much smaller scale?