Hi there- one of my colleagues does AAR dating, though they use it extensively as a relative age dating tool. This makes sense, since chemistry is a whole lot easier to change than atoms.
Effectively, a suite of fossils found in the same strata can be reasonably expected to have experienced similar diagenesis, and thus racemization of amino acids can tell you something about the relative ages of these fossils. Disparate fossils, like the bones Coyote studies, aren't really as datable by this technique. (see here:
http://gsa.confex.com/...SE/finalprogram/abstract_118080.htm )
Indeed, AAR isn't really even interchangeable between different species (see
http://gsa.confex.com/...SE/finalprogram/abstract_118080.htm ), so its utility is fairly specific. If well-calibrated it can be a potent technique, however, especially on marine samples.
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