Photosynthetic autotrophs are organisms that make their own food from sunlight through the work of pigments in chloroplasts. It is thought that chloroplasts in these organisms were once self-sufficient cells.
For the leaves to be presearved as fossil, they have to undergo a natural process of carbonization. This involves a slow chemical reaction with water over time that allows oxygen, nitrogen, and hydrogen to escape the leaves’ structure as gases leaving behind a carbon skeleton/film.
