It turns out that dead organisms' amino acids racemize slowly -- another way to measure how long something has been dead. But you need to know about the past temperatures. (Or you can use racemization as a climatological chronometer if you know the age independently.)
It turns out that creationists love talking about racemization.
Here's an interesting web page that
discusses racemization:
www.creation-science-prophecy.com/amino/
and other
origin of life issues.
Here's another
page
at the
Institute
for Creation Research.
The bottom line of these arguments is that
it is very difficult to calibrate
racemization timescales. If you
choose to deliberately consider only some
evidence, you might make radically
different conclusions about (for instance)
the age of the Earth than a geologist would.