Home » Science » Megalodons may have grown to the size of school buses by eating their shark siblings in the womb, new research suggests
Megalodons may have grown to the size of school buses by eating their shark siblings in the womb, new research suggests
October 8, 2020
Megalodons — huge, prehistoric sharks — reached lengths of 50 feet, with heads the size of cars.
The predators are super-sized compared to other sharks, both living and extinct. But how megalodons achieved that massive size is a mystery.
A new study suggests the sharks' size could be explained in part by the fact that they ate each other in the womb.
Scientists aren't sure how megalodons hunted, but a decline in prey and an increase in competitors may have caused their extinction.
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A megalodon's head alone was the size of a car.
The prehistoric monster was largest meat-eating shark to ever roam the oceans: It reached lengths of 50 feet, with dorsal fins that jutted 5 feet out of the water.
The ancient predator has been thrown into a cultural and scientific spotlight in the last few years after nearly a dozen new studies and a 2018 Hollywood blockbuster revitalized interest in the "Meg."
Researching the creature is difficult, since all we have left of the "Meg" are its 6-inch long, serrated teeth. That makes it challenging for scientists to figure out how how large these creatures actually got and why they were able to reach such enormous sizes.
But new studies that examine Megs' descendants are helping us understand the prehistoric shark's size in new ways.
One analysis, published on Monday, suggests that baby megalodons may have set themselves up to get super-sized before they're even born.
Meg eggs hatch inside the womb, where they grew ever bigger and hungrier before their mothers give live birth. But not all embryos survive the gestation process: Some are eaten by their womb-mates.
"'Early-hatched' embryos will begin to eat surrounding unhatched eggs," Kenshu Shimada, lead author of the study and a professor of paleobiology at DePaul University, told Business Insider. "The consequence is that only a few pups will survive and develop, but each of those pups can become considerably large in body size at birth."
Elusive fossil evidence makes the Meg's size 'hard to pin down'
Shimada's group first wanted to pin down how big megalodons could get.
So the researchers looked at how Meg's modern relatives, called lamniforms, live today. These sharks — which include great whites, makos, and sand tigers — have the same diet and body type as Meg did. So Shimada measured the size ratio between those sharks' teeth and body proportions, then applied that comparison to fossilized megalodon teeth.
That revealed that the maximum length a Meg could get is about 50 feet (15 meters) — more than double the length of a great white, the biggest shark alive today.
"This does not mean that Megalodon individuals larger than 15 meters did not exist, but their existence has not been substantiated based on scientific specimens in museum collections," Shimada said.
Indeed, a group of UK researchers did similar tooth-body comparisons in a September study, and found that megalodons could have been 52 feet long. That research also showed that a 52-foot (16-meter) megalodon had a head and tail 13 feet (4 meters) long, and a dorsal fin equal to the height of an average woman.