For the evolutionary timescale other kinds of watch, such as the potassium-argon watch, are suitable.
https://en.wikipedia.org/wiki/Potassium%E2%80%93argon_dating
One of the most widely used is potassium–argon dating (K–Ar dating). Potassium-40 is a radioactive isotope of potassium that decays into argon-40. The half-life of potassium-40 is 1.3 billion years.
