All the ideas on what conditions existed on the Earth to support the evolution of life are mere speculation.
There are indeed some records from geological processes. However, being able to tell exact dates is suspect.
I guess I'm thinking more along the lines of very early atmospheric and oceanic conditions. It seems that there is some disagreement on the oxygen content of the atmosphere and the gravitatioal attraction. From what I've read on these threads lately there are fossils that support both the oxygen rich and oxygen poor atmosphere. There was also the discussion about a flying creature that would have required a denser atmosphere to fly which would have required a stronger gravitational attraction. Aren't there also dinosaurs which would have required less graviation to survive; for example: for the blood to flow up their necks?