As long as a bus, weighs a ton and has teeth the size of a palm: the Megalodon was a superlative shark. And it may have reached a top position in the marine food web unmatched by any other ocean predator since. This is suggested by work by Emma Kas of Princeton University and her team in Science Advances. When the giant shark was alive during the Miocene and Pliocene, the food chain was possibly a little longer than it is today.
For their study, Kas and co used a new technique that analyzes food chains based on the ratio of nitrogen isotopes in organic molecules from tooth enamel. This corresponds to the corresponding levels of nitrogen in dental collagen, which is used by modern-day sharks to determine their position in the food chain. The higher an animal ranks there, the greater the ratio of Nitrogen-15 to Nitrogen-14 because they get more Nitrogen-15 from their diet.
The team found significantly higher levels of nitrogen 15 in the megalodon than in great white sharks, polar bears or killer whales. It concludes that the megalodon preyed on even more carnivores than other top oceanic predators, living or extinct—at least, any known to date. It is known that the shark preyed on minke whales, and other sharks have also fallen victim to it.
However, the scientists detected a wide range of nitrogen 15 levels in the megalodon teeth: not every conspecific reached the top of the food chain. This position could not prevent extinction anyway. Climate changes at the end of the Pliocene and the emergence of the agile great white shark caused the species to disappear 2.6 million years ago.