The first part of your comment seems to be replying to a pure strawman, and missing the point of my argument. My point was even small natural reactors leave very obvious evidence, so it seems like a city's worth of metallurgy could be detected 200m years later, probably by a surprised geologist in the 1800s. The fact that we haven't seen anything is conclusive evidence that modern humans were the first metallurgists.

  Yes, that's why I'm careful to qualify it with "technological", which is by implication the whole thing we do with metals and minerals and oil and all that stuff. 

"And minerals" is doing a lot of work, and it is just wrong to exclude plant/animal domestication from technology. Likewise earthworks, irrigation, trading networks and currency, etc. You're being very dismissive and closed-minded about what technology is. ("lived like hippies")

In particular, there don't seem to have been any dinosaurs that had anything like primate hands, so they would have never built real tools or weapons, or manipulated fires. That doesn't close off the possibility of an "advanced civilization" unless you mean "uses tools as fancy as ours." We don't actually know what 200,000 years of natural domestication would look like.