If you read any of Chronicler's/Karkovice's collaborative stories having to do with the Rainbowfaces. It basically boils down that the rainbowfaces actually had a human/like modern day society going about 10,000 years or so before the events of the LBT Movies and stuff.
They left the planet, for reasons you can read the stories for, but the main thing I'm getting at here is that in the fanfiction, there is little to NO evidence now of their being a modern day society in LBT, and this actually makes a lot of sense.
Really anything manmade breaks down pretty quickly, when you think about centuries and milleniea. Any kind of metel will pretty much turn into an unrecognizable pile of rusty dust. (except like aluminum and a few other metal I think? How long do those last?) Plastics will EVENTUALLY break down, though I think it can take a similar amount of time. Anything made out of wood will basically waste away to nothing, unless it's preserved in just the right way.
Really, the things we have to look at human society from the order of magnitude of thousands of years ago is pottery, and marks left in stone, and skeletons and stuff. Things that survive longer survived in very dry areas, with little to no water to corrode things.
Also, when you really think about it, any kind of fossils that are old enough are really just rocks, with any substance that made up the bone, like calcium, replaced with other minerals and things. How far back can you even carbon date any kind of fossilized tissue?
even DNA itself has an experiation date. Even under the best circumstances, DNA will break down into something unrecognizable in a few million years. It's the reason any usable dinosaur DNA has never been found. It's pretty much all broken down by now beyond any useful way to recreate it in any way to make new dinosaurs.
So, I'm just asking this question, and maybe Pangaea or Chronicler could chime in, or anyone else with some knowledge in the subject. What exactly would remain after the dinosaurs, 60 million or so years ago?
If, for example, some dinosaur wearing a complete suit of metal armor died 60 million years ago, will anything remain of the metal to let us now that that fossile of the dinosaur actually wore a full metal suit? Would you like, have to examine the rock around the fossile for remnants of the oxidized form of the metal? How do you know that it used to be in the form of actual sheets of metal? Is this just a stupid question?
What would be left that's detectable?
I know this is a very... complicate subject, but it sounds like something interesting to discuss, hypothetically, of course.