It is. I wish the conspiracy theorist 'the pyramids could not have been built by humans' etc etc crowds didn't exist, because I wish there was space to theorise about pre-human, pre-ape intelligent culture just for fun.

Same with UFOs. It seems to have changed in the past few years, but for a long time interest in them was associated with wackiness, and it was not something you could really discuss with a genuine sense of interest without the stain of appearing to believe something you didn't. It's intellectually and socially important to be able to be able to be curious and speculate without the appearance of belief in something.

That 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.

Was the sense of wackiness wrong though? Nearly all UFO claims went away once high quality cameras in smartphones became ubiquitous. It's useful to play around with ideas, yes, but it's also important to acknowledge that some ideas simply are wishful thinking.