The diet of fossil extinct animals can hold clues to their lifestyle, behaviour, evolution and ultimately extinction. However, studying an animal’s diet after millions of years is difficult due to the poor preservation of chemical dietary indicators in organic material on these timescales. An international team of scientists led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, applied a new method to investigate the diet of the largest shark to have ever existed, the iconic Otodus megalodon. This new method investigates the zinc isotope composition of the highly mineralised part of teeth and proves to be particularly helpful to decipher the diet of these extinct animals.