I read recently that trees and woody plants evolved a long long time before bacteria evolved that could digest the wood. If the coal and oil deposits were created in an environment without that bacteria, then when we run out of oil, we will have very little oil left and more won't be made even if you waited millions of years.
Imagine if a future intelligent species (likely not mammalian species either) examines the fossil record of its time and learns that we lived hundreds of millions of years ago in a time of free oxygen, followed by the vast majority of oil suddenly being missing in the fossil record, followed by a period of only anaerobic life, and then a whole second story of evolution. Those creatures will freak the fuck out if they find evidence that we had a culture in the fossil record. They might even find evidence of human technology that is more advanced than theirs. I wonder if they would wonder why we didn't industrialize with nuclear power? They almost certainly will find evidence of nuclear technologies. They will wonder why we killed ourselves.