From the Atlantic: Was There a Civilization on Earth before Humans?
"We’re used to imagining extinct civilizations in terms of the sunken statues and subterranean ruins. These kinds of artifacts of previous societies are fine if you’re only interested in timescales of a few thousands of years. But once you roll the clock back to tens of millions or hundreds of millions of years, things get more complicated."
Hey guys, try to keep up. I can't be the only one that's read Toolmaker Koan or The Green Marauder. Or Jack Vance, come to that.