Tests of the ¹³C contents of carbonates and collagens from bone of American Indians,Peruvian llamas (fossil and modern) and Tanzanian animals <i>(Procavia johnstoni and <i>Heterohyrax brucei) could distinguish quality and sometimes quantity between diets of these species, e.g., land (caribou or buffalo) vs. aquatic (seal or fish) animals and corn (C<sup^{b>4 plant)} ^{vs. other} ^plants ^(C<s<sup^b>3) ^{for the Indi}C fractionation during the process of synthesis of the bone materials from dietary C-containing materials. Although the carbonates of bone are not well preserved in fossils, collagens often are, and can be useful in this type of analysis. Evo-lutionary dietary tendencies can also be shown by this method. -- AATA