[AndrewC]

No---all that means is that the "error" in the "clock" is better defined.

Each species has a clock that is different. Which is the correct clock compared to the sun?

[Wonder Warthog]

"Each species has a clock that is different. Which is the correct clock compared to the sun?"

They're ALL correct "compared to the sun"--FOR THAT SPECIES. What waits to be discovered is how all those DIFFERENT molecular clocks relate to one another. Once we have THAT information, THEN we will be able to develop a "master clock" that we CAN accurately extrapolate back in time.