alt Hacker NewsThat ol' Silurian Hypothesis is fun, but, knowing how damn smart birds are, it's not inconceivable that the theropods could have become advanced enough to be at least tool-users.
Of course, now, we know they probably had as much similarity to lizards as we do.
Another interesting thought experiment is an octopus civilization. They are probably smart enough to have also developed along those lines.
Depending on what that civilization would have looked like, there might not be much left.
I remember reading an essay (probably linked from here), that it might only take a couple of million years, to completely wipe all traces of even an advanced, mechanized civilization. They posited that the only evidence of our civilization, in a few million years, would be marbles.
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> that it might only take a couple of million years, to completely wipe all traces of even an advanced, mechanized civilization.
It depends who comes searching. u235 has a half-life of ~700m years, so finding it in enough places (i.e. rocket silos, even if underground) and obviously processed into spheres, would raise some advanced alien eyebrows. There's also a chance that some things we left on the Moon / in high orbits will survive for a few million years. (also the test tubes on Mars and the rovers themselves, some have RTGs which, even if "depleted" of usable energy might still register as artificial)
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In a couple million years, what you’ll see are the mineral deposits where dumpsters are today, with all the materials that are not economically viable to recycle, but that will remain as they were for very long times - metal alloys, rocks that shouldn’t have formed at that time and place, oil deposits where plastics were that appear much older than the adjacent substrate in carbon dating, and so on.
The shape is erased, but the chemical composition mostly remains.