Answer: Atmospheric gases, especially carbon dioxide (CO2) and oxygen (O2), are extremely important for living organisms. Carbon dioxide and oxygen are the gases in the atmosphere that are needed for life. Plants need carbon dioxide for photosynthesis. They use sunlight to change carbon dioxide and water into food. The process releases oxygen
I don't know if this helps or not but you would want to know the age of the rock (absolute dating) and from there you will be able to know the age of the fossil and what caused it to die.
