 Cholestane in the fossil record is often interpreted as an indicator of ancient animal life and is often used by geochemists and geobiologists to reconstruct animal evolution (particularly in very early Earth history; i.e., Ediacaran, neo-Proterozoic and Proterozoic).Oxygen is required to produce cholesterol; thus, the presence of cholestane suggests some trace of oxygen in the paleoenvironment.However, cholestane is not exclusively derived from diagenesis of animal-derived biomolecules; cholestane has also been associated with the presence of rhodophytes.