I think it might be helpful to consider what happened to the dinosaurs. The same could happen to us if we fail to evolve in time...
Asteroid hits. Wipes out almost all life. A million years later, the biomass around us will have all been converted to a black ooze (oil), covered by millennia of rock, sediment, and tectonic plates. Eventually future civilized beings who plunder the Earth for our biomass that has been converted to oil and coal discover uncanny hard-to-explain remnants of a past civilization of, get this, bipedal animals.
Asteroid hits. Wipes out almost all life. A million years later, the biomass around us will have all been converted to a black ooze (oil), covered by millennia of rock, sediment, and tectonic plates. Eventually future civilized beings who plunder the Earth for our biomass that has been converted to oil and coal discover uncanny hard-to-explain remnants of a past civilization of, get this, bipedal animals.