Molecular clock is a scale which uses a technique whereby evolutionary time for different life forms is deduced from the mutation rate of biomolecules. Biomolecular data used for calculations in order to come up with the prehistoric time scale normally uses nucleotide sequences for DNA or amino acid sequences for proteins.
Hence, in order to develop a molecular clock, one would need: a sequence of molecules, the rate at which changes occur in a type of molecule and how much total change has occurred in a type of molecule from different species.
