We are cavemen with Iphones. There's plenty of evidence of that in society right now.
I would never say we know everything (we know almost nothing) but the amount that we understand about the physical laws of the universe do somewhat limit the potential energy sources that could be wielded to create an advanced civilization, and almost all of them leave some sort of trace geologically.
Regarding the potential for civilizations buried beneath the ocean- I wholeheartedly agree and am a personal believer in there having been proto civilizations in places like the red sea valley, the persian gulf valley, the bay of gujarat etc. that help explain shared deluge myths and cultural similarities between early examples of civilization. But thats ~25-15,000 years ago. Anything beyond that enters the realm of fantasy- in part because it essentially exists as something we could never really know, and in part because the unlikelihood that we wouldn't have found even a shred of evidence (I noticed you avoided my extinction event comment which IMO is actually the most interesting potential evidence...) that something like that did exist on earth ~250 million years ago. We're not just talking about being buried by the ocean on this scale, but perhaps completely subsumed into the crust of the earth. Pangea was still around.
And after all, who ever said that a civilization had to be land based at all? What if intelligent sea creatures existed at once? The ocean has always covered a larger part of our planet, and life started there most likely.
Could it have been? Maybe. Doubtful IMO based on everything we know. But Maybe. Anything is possible. I give much higher odds to life having developed on Venus or Mars than I do to prior civilization existing on earth.
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