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This is actually a somewhat active area of research https://en.wikipedia.org/wiki/Silurian_hypothesis

The absence of detectable plutonium-244 (half-life of 81.3 million years) is one indication that we are ~probably the first civilization on Earth to discover nuclear fission.

We'd have been able to see, for example, ice cores showing chemical changes in the atmosphere from industrialization. You can't carry out the same kind of massive activity that humans did without leaving some evidence. Even the Black Death was observable in ice cores on account of fewer humans burning wood.

Humanity has left many traces. An interesting example is a vast amount of chicken bones buried underground.

None of which are even close to even 100,000 years old, let alone a million or 100 million.

We have stone tools from a few million years ago. Modern things are much larger and numerous so would be much easier to find and last longer.

https://www.livescience.com/archaeology/human-evolution/2-6-...

We don’t know it hasn’t, but we have no evidence it has.