We have not carried out S-isotope analyses on bones but have looked at trace
sulfur in teeth and kidney stones. We have preferred the in vacuo Kiba
 stannous ion in dehydrated phosphoric acid) technique of A. Ueda and H.
Sakai (1983), Geochem. Jour.17, 185-196 because it chemically defines a
sulfide and sulfate component and provides measurements of concentrations
and delta 34S values thereof. The technique was developed originally for
volcanic rocks where the sulfide fraction would correspond to minerals. With
biological materials, there is a likelihood that this fraction relates to
organic sulfur. One gets into a dilemma here because some sulfur groups in
organic compounds are reduced to H2S by Kiba reagent whereas others are
rather resistant.
Results on kidney  stones can be found in
H.R.Krouse et al, (1987) Applied Geochem.2, 205-211,
These data and a few on fish and human teeth are included in a summary  by
H.R.Krouse and A.Ueda (1987) ,  "Sulphur Isotope Analyses of Trace Sulphide
and Sulphate in Various Materials using Kiba Reagent,"  pp 113-121 in
Studies in Sulphur Isotope Variations in Nature which is the Proceedings of
an Advisory Group Meeting of the IAEA held in Vienna, June 17-20,1985.
There are scattered data elsewhere that do not reveal additional basic
information. One clear point is that sulfate in fish teeth does not bear an
isotope composition consistent with direct precipitation of dissolved
sulfate in the surrounding water but rather that of oxidized organic-S
 which in turn was produced by assimilation of the surrounding SO4=.)
Roy Krouse