It's not certain it could be useful: Humans and animals have a relatively short lifespan compared to major climatic changes - although we are about to put that to the test, unfortunately. Another thing that hampers the usefulness is that you'd need a continuous record where you need bones with overlapning life times, much like the tree rings. One argument to use though, as it's done with corals, for seasonal and even diurnal temperature swings in the sea surface, is to be able to glean the oxygen isotope ratios (delO18), to get geographic provenance data and/or perhaps shifts in the oxygen isotopes as a cause of a changing climate - the latter is very very sketchy, since the body regulates temperature and is a fractionating factory of isotopes in itself. Keep thinking about it, you may think up something new!- it's the only way forward towards possible progress.

Best Wishes,

Jacob Mey

Metals have been used to pinpoint travels of Bog people (bodies preserved in bogs). You are what you eat and depending on regions traveled to and from certain metals show up in the food consumed in particular areas with high concentrations. From that to seing temporal archived changes is hard - after a certain age we don't grow any more and our cells are replaced as we go. I'm no expert on this, but my guess is that teeth could contain a possible archive of metals from early to late development in both humans and animals.

best wishes,

Jacob Mey