The nitrogen in the air cannot be used by producers and consumers. It must be fixed or converted by bacteria in the ground into a useable form for plants called nitrates. Some plants called legumes (beans and clover) actually have bacteria in their roots.
Answer: ok first you have to look at the clues or hints of what the given fossil and how many layers or solid Rock on it, now that is seen to go from the youngest to oldest age, we now know that you can design a procedure like a "Rock identification" based on what type of or rock it is for example lime stone this would tell you how far it goes back in time. Just identify the tpe of rock it is and then youll know that its that deep.
I hope this helps just wrote this from scratch for you :)
