The reconstruction of ancient diets from trace element analysis of surviving bones is an intriguing concept. Unfortunately, the concept is based more on fallacy than on fact, since the concentrations of many elements in archaeological bone bear minimal resemblances to their concentrations in clean' living bone. Analytical data on clean modern human bones, Egyptian mummy bones, <i>Rhesus macaque</i> monkey bones, soil-buried bones, bog-buried bone, and dinosaur bones are presented for up to 32 elements. The data show that the archaeological criteria by which surviving material is classified as bone are quite unacceptable for medical and dietary studies. This, in turn, severs the link between trace element analyses of ancient bones and realistic ancient dietary assessments.