https://www.scientificamerican.com/article/no-there-wasnt-an-advanced-civilization-12-000-years-ago/

We would have to go back hundreds of millions of years when there were no homosapiens and a different species built a civilization in which any trace is now ground to dust.
We’re used to imagining extinct civilizations in terms of 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.

I don’t believe the Earth once hosted a 50-million-year-old Paleocene civilization. But by asking if we could “see” truly ancient advanced civilizations, what is left is life itself in DNA or other unknown things to look for. Some things will always be unseen but as they say anything is possible, just not likely.

Did someone mutter exo aliens? Sorry Bill the only evidence is for actual flying objects, everything else are just stories.