Largest shark that ever lived: Scientists unlock mystery about the megalodon

USA Today

12-03-2025

The monster shark, depicted in the 2018 sci-fi horror film 'The Meg,' dominated the ocean 3.5 million years ago.
USA TODAY
The biggest, most formidable shark to have ever roamed the ocean may have been even larger than previously thought, according to a new study.
The research, published Sunday in the journal 'Palaeontologia Electronica,' suggests that the megalodon, which dominated the ocean 3.5 million years ago, was more than three times the size of a great white shark.
The monster shark, depicted in the 2018 sci-fi horror film " The Meg," was previously believed to be between 50 and 65 feet long. But the new study, conducted by researchers in 28 countries, found the megalodon could have reached a whopping 80 feet in length, roughly the size of two school buses.
The study helps confirm the hypothesis that the megalodon was not 'merely a gigantic version of the modern-day great white shark,' as previously thought, said Phillip Sternes, an educator at SeaWorld San Diego and a researcher on the project. Instead, the shark could have closer cousins today.
It also sheds light on the mystery of how the fearsome carnivore may have gone extinct millions of years ago – and the role the smaller great white shark played.
How big was Megalodon?
Scientists have long struggled to determine the size of the megalodon because no complete fossil of the extinct animal has been found. Past studies have estimated the megalodon's length and body shape by comparing it to the great white shark, which has similar large, serrated teeth.
But Sternes said those studies relied on assumptions about similarities between only the two shark species.
The new study compared megalodon fossils with more than 150 living and extinct shark species. It found the megalodon may have had a longer, more slender body resembling that of the modern lemon shark, rather than the great white. It could have ranged between around 54 feet long and 80 feet long, the study suggests.
And that longer length isn't just a fun fact about the fearsome creatures. It could also paint a clearer picture about the way megalodons moved through the water.
Kenshu Shimada, a paleobiology professor at DePaul University in Chicago who led the study, said findings about the megalodon's maybe-slender body align with what scientists already know about other gigantic aquatic animals: Thinner bodies allow long animals to swim more efficiently.
If the megalodon was a similar shape and size to the modern great white shark, that stocky body would 'not allow it to be an efficient swimmer,' to catch prey and survive, Shimada explained.
So what killed the megalodon?
Little is known about how and why megalodon went extinct around 3 million years ago. But the study says the great white shark could have had something to do with it.
The fossil record and 'inferred growth patterns,' suggests that the rise of the great white shark, and the competition it brought, actually helped lead to the demise of the megalodon, the study states.
Researchers are still investigating the megalodon's evolution, but Sternes told USA TODAY one possibility is that the predator's large body might not have been as adaptable as smaller shark species, even if it could swim freely.
'We've learned about how the planet fluctuates with different environmental factors, how life responds to it,' he said. 'Understanding the past can better inform us about both the present and the future for life on Earth.'