There are three things that we use to deduce that gravity as created on the 2nd day, which means that the during first day, and the time before it, there was no gravity in the universe.
Life Began in Zero-G
Archaeopteris (Dawson): A case study in the applicability of phylogenetic analysis to fossil taxa
Cladistic phylogenetic analysis is circular reasoning based on personal bias.
Depositional Environments
Interesting thing about fossils: Fossils don't just record evidence of ancient life, they also show us clues about what the environment was like when the fossil was made, or deposited.