For decades, the giant prehistoric shark known ominously as “The Meg” has been portrayed as a massive apex predator that hunted the only formidable opponent in the oceans at the time: whales. But new research suggests the reality was more nuanced — and a lot more interesting.
In a study published in Earth and Planetary Science Letters, scientists used advanced geochemical techniques to analyze fossilized tooth enamel and found evidence that indicate this now-extinct behemoth likely had a more varied and opportunistic diet, feeding on whatever was available in its environment to satisfy its immense appetite The key to figuring out this mystery lay in the isotopes of zinc preserved in its teeth, which serve as chemical fingerprints of what an animal ate during its life.
Researchers led by Dr. Jeremy McCormack at Goethe University in Germany analyzed 209 fossil teeth from 21 different species (both marine and terrestrial) dating back to the early Miocene period, roughly 20 to 16 million years ago. The fossils were collected from sites in what is now southern Germany, specifically a shallow seaway that once connected the ancient seas known as the Upper Marine Molasse. By focusing on a specific time and place, the team were able to compare Megalodon’s diet with that of other sharks, dolphins and marine animals living at the same time.
What makes this research stand out is its use of zinc isotope ratios (specifically δ⁶⁶Zn) as a tool for estimating an animal’s trophic position, or its level in the food web. While nitrogen isotopes (δ¹⁵N) have traditionally been used to track trophic levels, they can degrade over time, especially in fossils millions of years old. Zinc isotopes, on the other hand, are much more stable and are now emerging as a reliable alternative. The higher an animal is in the food chain, the lower its δ⁶⁶Zn values tend to be, because heavier zinc isotopes are preferentially retained in tissues lower down the food chain, while top predators, which eat those animals, end up with lighter zinc signatures.
In this study, Megalodon teeth consistently showed some of the lowest δ⁶⁶Zn values across the entire fossil dataset, placing them at the very top of the marine food web. The researchers also looked at the extinct Carcharodon hastalis, which is a possible ancestor of the modern great white shark, and found its δ⁶⁶Zn values were slightly higher. This suggests it fed at a slightly lower trophic level or had a different diet, supporting what many paleontologists have long suspected — that Megalodon was a top predator, likely preying on large marine mammals such as whales and dolphins. Finally, the scientists analyzed modern marine species, including sharks and dolphins, to create a baseline for comparison. They found that even today, top predators like killer whales have similarly low δ⁶⁶Zn values, further supporting the idea that zinc isotopes accurately reflect trophic level.
Paleontologists have long suspected that Megalodon was a top predator based on its massive size, tooth morphology, and fossil evidence showing bite marks on whale bones. What this study does is go a step further by providing chemical evidence that directly links Megalodon to a high trophic level, rather than relying only on anatomical or circumstantial evidence. See, scientists face major challenges when trying to reconstruct what a creature like Megalodon actually ate. Sharks have skeletons made mostly of cartilage, which doesn’t fossilize well, so researchers often rely on teeth. While bite marks on fossilized whale bones have been strong evidence of marine mammal being part of the Meg’s meals, bites on other sharks leave less obvious traces, making dietary conclusions based only on physical bite evidence tricky and potentially misleading.
This new chemical analysis helps fill in those gaps.
By creating a kind of prehistoric food web, the researchers placed animals like sea bream (which eat mussels and crustaceans) at the bottom, followed by smaller sharks and extinct toothed whales the size of modern dolphins. Megalodon still sat near the top, as expected, but its zinc isotope levels weren’t wildly different from those just below it in the chain, suggesting that those species may have ended up on the menu too.
While the conclusion itself (big shark ate big animals) isn’t groundbreaking on its own, the method is what’s novel and important. This is the first time zinc isotopes have been used in this way for extinct marine predators, and the fact that the values line up with what we see in modern apex predators opens the door to re-examining other ancient species’ diets and food web roles with greater precision.
Still, it seems that ancient ecosystems are not so different from today’s. Apex predators existed, food webs were complex, and adaptability was key to survival. Megalodon may have ruled the oceans, but not alone… and not without competition.
