Warning, massive spoilers:
There are like 5 or 6 mass extinction events followed by a new civilization each time built by a different specie. At some points a raven civilization goes on the moon (they always had an innate tendency to go higher) and find an old rover, then it jumps to another civ. and the earth is totally smooth and people are living in holes in the ground (this might be another story from Baxter). Then it's some earth inner core creatures fungi-like. It ends with the sun expansion making life on earth impossible and a mars creature pondering all that.
Rings any bells ?