The great white shark competed with the giant megalodon for prey, a prehistoric giant that dominated oceans until about 3.6 million years ago and could reach lengths of around 20 meters. Scientists say the rivalry for food may have helped drive the massive species to extinction, a finding reported in Science and Nature Communications.
Researchers analyzed zinc isotopes preserved in fossil teeth. This method offers a window into ancient diets and food chains, helping scientists place extinct animals within their ecosystems millions of years in the past.
In a collaborative effort between German and American institutions, the work traced the overlap in the food webs of the gigantically predatory megalodon and today’s great whites. The fossils studied come from what is now the southeastern United States, with evidence dating to the early Pliocene period between 5.3 and 3.6 million years ago.
Many explanations have been proposed for the megalodon’s gigantism and eventual disappearance. Among them, competition for prey with sharks and other large predators stands out as a likely factor.
Kenshu Shimada, a researcher at DePaul University in the United States, expressed that there was probably significant prey overlap, and that the modern great white could have been more efficient at capturing those prey. Over time, this would have reduced the food sources available to the megalodon, contributing to its decline. The study adds weight to the idea that diet overlap played a key role in the extinction pattern observed in these ancient sea monsters.
How can scientists determine the diet of extinct species
The study shows stable zinc isotope levels in tooth enamel, which is the most mineralized part of the tooth. This approach provides results that are similar to established methods based on nitrogen isotopes in tooth collagen. However, collagen preservation is often insufficient for analysis in fossils dating back millions of years.
The published work explains that enamel zinc isotope signatures can reveal diet and trophic ecology in extinct sharks. Thomas Tutken, a professor at the Institute of Geosciences at the Johannes Gutenberg University, notes that this method preserves diet signals in enamel crowns of fossil teeth. He explains that zinc isotopes could be used to study diet in extinct animals and their feeding relationships across other ancient groups, including early human ancestors. Jeremy McCormack of the Max Planck Institute for Evolutionary Anthropology adds that this technique could extend to multiple fossilized species from millions of years ago, opening new avenues for understanding prehistoric ecosystems.
These insights underscore how diet tracing can illuminate the ecological dynamics that shaped ancient oceans and land ecosystems alike, offering a clearer view of how predators and prey interacted long before modern humanity emerged.
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