How could the demise of the largest ever apex predator have coincided with the rise of one of today’s apex predators? One theory that aligns with the analysis in the latest research is that a changing climate is responsible. There then appears to have been a shift as the great whites – the newcomers, the underdogs – relegated megalodon and took over. The presence of the same levels of different zinc isotopes suggested that great white ancestors and megalodons once ate the same food and occupied the same position in the food web. In this case, different zinc isotopes can indicate what sort of diet a fossilised animal had and where it sat in the food chain. Isotopes are variants of an element that act as a sort of chemical signature. So how do you investigate the diet of a long-gone animal, when only its teeth have survived? To solve this problem, scientists looked for concentrations of zinc isotopes in the fossilised teeth of megalodon and in teeth of past and present great whites.
