I never said it was handed down from 3 million years ago. I don't subscribe to the idea that Antarctica was the real Atlantis. As Plato was the only ancient source for the story, attributing it to an unnamed Egyptian source, via Solon, via another member of Socrates' circle, I see Timaeus and Critias as transitional philosophical exercises originating with Plato, but perhaps rooted in old lore.
My guess is that the whole story of Atlantis was a complete fabrication by Plato. Oral traditions are rarely reliable even over a few centuries. Of course over 3 million years would be totally preposterous. We don’t even know if the australopithecines had language. Maybe something a little more sophisticated than the communications practiced by present-day great apes, but probably way short of human language.