I often think about the possibility of a technologically advanced civilization in earth's ancient past that rivaled or even exceeded our current one.
There is one thing that has me thinking such a civilization did not exist. Mineral resources.
Human activity is dilutive in respect that they mine out concentrated mineral deposits (like copper), make things with the metal, and those things get spread all over the place.
If there was an advanced previous civilization, then there should be signs of mineral deposit depletion and distribution in a way that makes recovering those things difficult. Think of copper again. Old wires and things turned back into copper oxides near the surface but in low concentration deposits that form odd line like structures over hundreds of miles.