What megalodon really ate to meet its 100,000-calorie daily requirement, according to a new study
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
CNN —
What scientists understand about the voracious feeding habits of the colossal megalodon could be up for some revision.
The prehistoric predator that went extinct about 3.6 million years ago was not hunting only large marine mammals such as whales as researchers widely thought, a new study has found. Instead, minerals in fossilized teeth reveal that megalodon might have been an opportunistic feeder to meet its remarkable 100,000-calorie-per-day requirement.
'When available, it would probably have fed on large prey items, but when not available, it was flexible enough to feed also on smaller animals to fulfill its dietary requirements,' said lead study author Jeremy McCormack, a geoscientist at Goethe University in Frankfurt, Germany.
The study, published Monday in the journal Earth and Planetary Science Letters, also showed there were regional differences in the giant shark's feeding habits. The finding suggests megalodon would pursue whatever was in local waters, devouring other top predators and smaller prey alike.
'They were not concentrating on certain prey types, but they must have fed throughout the food web, on many different species,' McCormack said. 'While certainly this was a fierce apex predator, and no one else would probably prey on an adult megalodon, it's clear that they themselves could potentially feed on almost everything else that swam around.'
Megalodon dispatched its prey with a ferocious bite and lethal, serrated teeth that could reach up to 7 inches (18 centimeters) long — the size of a human hand. The superpredator's teeth — abundant in the fossil record — are what McCormack and his colleagues used to conduct a geochemical analysis, unlocking fresh clues that could challenge megalodon's role as sole king of the ancient seas.
Zinc in megalodon teeth
It's not the first time that a study has challenged previous knowledge about the enormous sea creature. In fact, many questions remain unanswered about Otodus megalodon — its scientific species name meaning 'giant tooth' — since no complete fossil has ever been discovered. The lack of hard evidence stems from the fact that fish skeletons are made of softer cartilage rather than bone, so they don't fossilize very well.
Recent research found that the animal was more warm-blooded than other sharks, for example, and there is an ongoing debate about its size and shape. Scientists who created a 3D reconstruction suggest ed in 2022 that megalodon was about three times as long as a great white shark — about 52 feet (16 meters). However, a March study hypothesized that the megashark was actually much larger — up to 80 feet (24 meters) in length and even longer than the fictional version in the 2018 blockbuster 'The Meg,' which suggested the ancient predator was 75 feet (23 meters) from head to tail.
As for megalodon's feeding habits, determining what it ate based on fossil evidence poses challenges, according to McCormack. 'We know that they fed on large marine mammals from tooth bite marks,' he said. 'Of course, you can see bite marks on the bones of marine mammals, but you will not see them if they fed on other sharks, because sharks don't have bones. So there's already a bias in this kind of fossil record.'
To glean more about megalodon's prey selection, McCormack and his coauthors looked at the giant shark's fossilized teeth and compared them with those of other animals that lived at the same time, as well as teeth from modern sharks and other predators such as dolphins. The researchers used specimens from museum collections and samples from beached animal carcasses.
Specifically, the study team conducted a lab analysis of zinc, a mineral that is acquired only through food.
Zinc is essential for living organisms and plays a crucial role in tooth development. The ratio of heavy and light zinc isotopes in the sharks' tooth enamel preserves a record of the kind of animal matter that they ate.
Different types, or isotopes, of zinc are absorbed when fish and other animals eat, but one of them — zinc-66 — is stored in tooth enamel much less than another, zinc-64. The ratio between those zinc isotopes widens the further away an animal gets from the lowest level of the food chain. That means that a fish eating other fish would have lower levels of zinc-66 compared with zinc-64, and the fish that eat those fish will have even less zinc-66 compared with zinc-64, creating ratio markers that can help draw up a sequence of the food chain.
The researchers found that sea bream, a fish that feeds on mussels and crustaceans, was at the bottom of their reconstructed chain, followed by smaller sharks from the Carcharhinus genus, up to 9.8 feet (3 meters) in length, and extinct toothed whales comparable in size to modern dolphins.
Farther up were larger sharks such as the Galeocerdo aduncus, similar to a modern tiger shark, and occupying the top slot was megalodon — but its zinc ratios were not so different as to suggest a massive gap with the lower-tier animals, meaning they might have been part of megalodon's diet, too. 'Based on our new results, we see that it was clear it could feed at the very top, but it was flexible enough to feed also on lower (levels of the food chain),' McCormack said.
In addition, the researchers found megalodon was not alone at the top of the food chain but instead shared the spot with other 'opportunistic supercarnivores' such as its close relative Otodus chubutensis and the lesser-known Araloselachus cuspidatus, another giant fish-eating shark.
That revelation challenges the assumption that megalodon was the exclusive ruler of the oceans and draws comparisons with the great white shark, another large opportunistic feeder. The finding also reinforces the idea that the rise of the great white may have been a factor in megalodon's extinction, according to paleobiologist Kenshu Shimada, one of the coauthors of the latest study.
'One of the contributing factors for the demise of megalodon has been hypothesized to be the rise of the great white shark, which feeds on fish when young and shifts its diet to marine mammals as it becomes larger,' said Shimada, a professor of biological and environmental sciences at DePaul University in Chicago.
'Our new study, that demonstrates the 'diet overlap' between the great white shark and megalodon, strengthens the idea that the evolution of the smaller, likely more agile and maneuverable great white shark could have indeed (driven) megalodon to extinction.'
Megalodon vs. great white shark
The new research allows scientists to recreate a snapshot of the marine food web that existed about 20 million years ago, according to Jack Cooper, a UK-based paleobiologist and megalodon expert who wasn't involved with the study.
'The general picture of megalodon has been of a gigantic shark munching on whales,' Cooper said in an email. 'This study adds a new dimension that megalodon probably had a wide range of prey — essentially, it probably ate not just whales but whatever it wanted.'
Another interesting find, he added, is that megalodon's diet probably varied slightly between different populations, something observed in today's great white sharks. 'This makes sense and is something we would have probably expected since megalodon lived all over the world and not all of its prey items would have done; but it's wonderful to have concrete data supporting this hypothesis,' Cooper said.
The study adds to a growing body of evidence that is reshaping commonly held beliefs about megalodon and its close relatives, said Alberto Collareta, a researcher in the department of Earth sciences at Italy's University of Pisa who was not involved in the research.
'These have led us to abandon traditional reconstruction of the megatooth sharks as 'inflated' versions of the modern white shark. We now know that the Megalodon was something else — in terms of size, shape and ancestry, and of biology, too,' Collareta said via email.
'The Miocene (palaeo)ecosystems in question did not work in a radically different way compared to their modern counterparts — even if they feature … completely extinct protagonists such as the megatooth sharks,' he added, highlighting what he found to be the report's key takeaway.
'That said, it is still useful to acknowledge that our understanding of the Meg is essentially limited to its ubiquitous teeth, a few vertebrae and a handful of scales. What I'd really love to see emerging from 'the foggy ruins of time' is a complete Meg skeleton… Let's hope that the fossil record will amaze us once again.'
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
an hour ago
- Yahoo
Researchers issue grim warning after making concerning discovery about ships in Arctic: 'Major drivers'
New research indicates that black carbon pollution — the soot-like planet-warming material released through the incomplete burning of fossil fuels — has reached higher levels in the Arctic than previously expected as a result of shipping activity in the area. While successful trading partnerships might bode well for the European Union and global markets, the number of ships in the Arctic is proving taxing for the environment. According to a late-May report from Euronews, previous studies have looked mostly at the emissions impacts from EU ships rather than also including impacts from other ships passing through the region, potentially skewing understanding of the industry's carbon footprint as effects continue to grow. "Our findings show that ships connected to EU trade, regardless of their flag, are major drivers of black carbon pollution in the Arctic," Liudmila Osipova, an International Council on Clean Transportation senior researcher, told the outlet. Euronews reported that estimates for the polar region point to a growth from less than 200 metric tons of black carbon in 2015 to over 400 in 2021 — over a 100% increase. Based on this trend, numbers are expected to rise further if pollution-heavy shipping activity persists. When it comes to black carbon, the major concern is its sheer potency in warming the planet. A single metric ton has the "global warming effect equivalent" to up to 900 metric tons of typical carbon dioxide, per Euronews. Higher levels of black carbon emissions in the polar region contribute substantially to Arctic ice melt — a phenomenon that could release long-frozen infectious microbes, sparking unprecedented disease outbreaks. Rising sea levels brought about by melting Arctic ice are also set to jeopardize coastal communities and exacerbate extreme weather. Events like hurricanes are part of life on Earth, but heat-trapping gases are supercharging their effects, with higher seas meaning storm surges can be more destructive and reach further inland than before. Accurately understanding a problem is generally the first step in addressing it. According to Euronews, prior black carbon estimates for the Arctic region have been projected well below the actual level, possibly misleading many to believe the issue hasn't been as serious as it actually is. Properly tracking emissions from all cargo ships — and funding research and development for more carbon-neutral ship technology — could be among the most beneficial steps forward. But municipalities and individuals will likely need to take further action in the short term. As ice sheets continue to melt, the resilience of homes to extreme weather can be improved with clean-energy upgrades, such as the installation of solar panels in conjunction with a battery system to maintain essential household power during grid outages. Clean-energy alternatives are becoming more widespread in communities too, and some municipal projects to protect coastal residents are moving forward even without full support at the national level. Other such initiatives around the world may require more prioritization and sustained investment to make a real difference. Learning about how to organize support for pro-environment policies could be a part of coordinating global efforts to mitigate the effects of international issues like shipping and supply chain impacts on human-caused climate change. Do you worry about air pollution in your town? All the time Often Only sometimes Never Click your choice to see results and speak your mind. Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.
Yahoo
2 hours ago
- Yahoo
Scientists make jaw-dropping find at base of Antarctic glacier: 'May be greatly underestimated'
Antarctica was once believed to host little biodiversity beyond coastal areas and a few hardy microbes, but a team of scientists has made a shocking discovery beneath a slowly retreating glacier in Antarctica: a bustling network of microbial life. A team of researchers aboard Germany's Polarstern research vessel traveled to the Larsemann Hills on the southern coast of Antarctica to analyze the biodiversity of disturbed soil near the glacier's edge. Their findings, titled "Advocating microbial diversity conservation in Antarctica" and published in Frontiers, revealed 2,829 genetically defined species, and the study revealed associations among these species that suggest that these organisms don't merely coexist; they collaborate to survive. One of the study's authors, Dr. Dirk Wagner, a professor at the GFZ Helmholtz Centre for Geosciences and the University of Potsdam in Germany, said, "Here we reveal unexpectedly abundant and diverse microbial community even in these driest, coldest, and nutrient-poorest of soils, which suggest that biodiversity estimates in Antarctic soils may be greatly underestimated." By analyzing both DNA from living and extinct organisms, researchers revealed a dynamic history of life that now provides science with a better understanding of how ecological succession and symbiotic relationships have transformed Antarctica's hostile environment into a hospitable habitat. One of the study's key discoveries is that these organisms cooperate. Cold-loving fungi could be breaking down organic matter to supply bacteria with carbon. Algae and bacteria appear to exchange nutrients, and different species have settled into unique zones proximal to the glacier. These discoveries suggest that this tightly knit ecological network could be the very thing that makes life hospitable in this harsh region. A study published in March found that conserving diverse microbial ecosystems in Antarctica in the face of the changing climate is crucial, as these organisms thrive in extreme conditions and influence nutrient cycling and carbon sequestration. The authors wrote, "By prioritizing microbial conservation, strengthening international cooperation, and integrating protection plans into policy frameworks, we can safeguard these invaluable ecosystems for future generations." Do you think America is in a housing crisis? Definitely Not sure No way Only in some cities Click your choice to see results and speak your mind. Join our free newsletter for good news and useful tips, and don't miss this cool list of easy ways to help yourself while helping the planet.
Yahoo
3 hours ago
- Yahoo
Scientists Working to Decode Signal From Earliest Years of Universe
As mysterious as the Big Bang that gave birth to the universe is the brief but tumultuous period that immediately followed it. How did the cosmos transform from a uniform sea of darkness into a chaotic swirl brimming with radiant stars? What were these first stars like, and how were they born? So far, we have very strong suspicions, but no hard answers. One reason is that the light from this period, called the cosmic dawn, is extremely faint, making it nearly impossible to infer the traits of these first cosmic objects, let alone directly observe them. But that's about to change, according to a team of international astronomers. In a new study published in the journal Nature Astronomy, the astronomers argue that we're on the verge of finally decoding a radio signal that was emitted just one hundred millions years after the Big Bang. Known as the 21 centimeter signal, which refers to its distinct wavelength, this burst of radiation was unleashed as the inchoate cosmos spawned the earliest stars and black holes. "This is a unique opportunity to learn how the universe's first light emerged from the darkness," said study co-author Anastasia Fialkov, an astronomer from the University of Cambridge in a statement about the work. "The transition from a cold, dark universe to one filled with stars is a story we're only beginning to understand." After several hundred thousand years of cooling following the Big Bang, the first atoms to form in the universe were overwhelmingly neutral hydrogen atoms made of one positively charged proton and one negatively charged electron. But the formation of the first stars unbalanced that. As these cosmic reactors came online, they radiated light energetic enough to reionize this preponderance of neutral hydrogen atoms. In the process, they emitted photons that produced light in the telltale 21 centimeter wavelength, making it an unmistakeable marker of when the first cosmic structures formed. Deciphering these emissions would be tantamount to obtaining a skeleton key to the dawn of the universe. And drum roll, please: employing the Radio Experiment for the Analysis of Cosmic Hydrogen telescope, which is currently undergoing calibration, and the enormous Square Kilometer Array, which is under construction Australia, the researchers say they've developed a model that can tease out the masses of the first stars, sometimes dubbed Population III stars, that are locked inside the 21 centimeter signal. While developing the model, their key revelation was that, until now, astronomers weren't properly accounting for the impact of star systems called x-ray binaries among these first stars. These are systems where a black hole or neutron star is stripping material off a more ordinary star that's orbiting it, producing light in the x-ray spectrum. In short, it appears that x-ray binaries are both brighter and more numerous than what was previously thought. "We are the first group to consistently model the dependence of the 21-centimeter signal of the masses of the first stars, including the impact of ultraviolet starlight and X-ray emissions from X-ray binaries produced when the first stars die," said Fialkov. "These insights are derived from simulations that integrate the primordial conditions of the universe, such as the hydrogen-helium composition produced by the Big Bang." All told, it's another promising leap forward in the field of radio astronomy, where recent advances have begun to reveal an entire "low surface brightness" universe — and a potentially profound one as well, with the promise to illuminate our understanding of the cosmic dawn as never never before. "The predictions we are reporting have huge implications for our understanding of the nature of the very first stars in the universe," said co-author Eloy de Lera Acedo, a Cambridge astronomer and a principal investigator of the REACH telescope. "We show evidence that our radio telescopes can tell us details about the mass of those first stars and how these early lights may have been very different from today's stars." More on astronomy: Scientists Investigating Small Orange Objects Coating Surface of the Moon
