FEEDING mechanisms may hold the key to understanding the selective pressures that led to the evolution of vertebrates(1-3). But in the absence of direct evidence, hypotheses of feeding mechanisms in the most primitive extinct vertebrates are somewhat speculative, and scenarios that seek to explain vertebrate origins remain controversial. The recognition that the affinities of conodonts lie among the most primitive vertebrates(4-6) shifts the balance in this debate, I illustrate here microscopic wear patterns on conodont elements that provide the first unequivocal evidence that they functioned as teeth. These microwear patterns were produced as food was crushed and sheared between opposed conodont elements brought into bilateral occlusion, The presence of teeth and evidence of macrophagy in such primitive and early vertebrates support hypotheses that the first vertebrates were predators.