The half-lives of several radioactive isotopes are known and are used often to figure out the age of newly found fossils.
Since fish diverges from the main stem of vertebrate evolution earlier than either birds or mammals, the cytochrome c of both mammals and birds should be equally different from the cytochrome c of fish.
I was thinking recently about how much of a double-edged sword online dating is.
One way that helps scientists place fossils into the correct era on the Geologic Time Scale is by using radiometric dating.
Also called absolute dating, scientists use the decay of radioactive elements within the fossils or the rocks around the fossils to determine the age of the organism that was preserved.
Differential solubility between uranium and its long lived daughter isotope Th is measured using MC-ICPMS.
This method has a dating range up to about 600.000 years.
Perhaps the most widely used evidence for the Theory of Evolution through Natural Selection is the fossil record.
The fossil record may be incomplete and may never fully completed, but there are still many clues to evolution and how it happens within the fossil record.
Remember the gender roles we were just expected to play out?