Still, land was not being colonized at least until 500m years ago and substantial biomass had not accumulated until around 400 or so million years. 750m years a

Still, land was not being colonized at least until 500m years ago and substantial biomass had not accumulated until around 400 or so million years. 750m years ago there was probably not much microbial life on the continents (outside water holes or rivers, or near shores).