The mitochondria needs oxygen the most because they are the energy-producers for cells
Mitochondria are rod-shaped organelles that can be analyzed the power dynamos of the cell, changing oxygen and nutrients into adenosine triphosphate (ATP). ATP is the chemical energy "currency" of the cell that controls the cell's metabolic actions.
They are organelles that act like a digestive system which takes in nutrients, breaks them down, and produces energy-rich particles for the cell. The biochemical methods of the cell are known as cellular respiration.
Hope this helps!
i think the miocene epoch spans the time from 23 million to 12 million years ago.