Five million years ago, huge predatory sharks patrolled the oceans. Their giant teeth — left in coastal sediments as spent lead — inspired the 1843 name that has since become a household word: megalodon.
Despite the fame of the giant shark, the exact size and shape of Megalodon has long been a matter of dispute. Because sharks’ skeletons are composed largely of cartilage, they are rarely fossilized, leaving researchers with wildly varying estimates — anywhere from 35 to 60 feet — using shed teeth and comparisons with living relatives such as mackerel and great white sharks.
But New 3D modeling of sharkpublished Wednesday in the journal Science Advances, It indicates that megalodon may have been larger, faster, and more spacious than previously thought.
In 2014, Catalina Pimento, a paleontologist at Swansea University in Wales, crossed paths with John Hutchinson, an anatomist at the Royal Veterinary College in London. Dr. Hutchinson specializes in computer modeling of extinct animals. The two eventually joined forces with a team of collaborators to build a three-dimensional megalodon computer model, based in part on scans of preserved spines discovered in the 1860s and based at the Royal Belgian Institute of Natural Sciences. They also used megalodon teeth and a full-body scan of a great white shark, the closest living counterpart to megalodon.
The resulting model suggested an animal that was 52 feet long and weighed 67 tons, about the size of a whale shark. It’s possible that the other megalodons are even larger, Dr. Pimento said. Other fossilized vertebrae are 50 percent larger than those used in the model, indicating a maximum length of 65 feet, which is longer than the modern humpback whale. Typical megalodon’s jaws can open wide enough to devour a 26-foot orca in as little as five bites.
How reliable is such computer modeling? “These reconstructions work very well when applied to live animals whose mass we know about, so they generally seem to be fine,” said Dr. Hutchinson. This is especially true given the natural differences in size between individual animals.
But some researchers point out that the model is based on assumptions about megalodons that have not been confirmed in the fossil record.
“The size and shape of other skeletal components, such as the skull, jaws and all the fins, is still my guess,” said Kensho Shimada, professor of palaeontology at DePaul University in Chicago.
However, if the team’s model is accurate, it will have repercussions on the predators’ enormous cruising speed — how fast the animal gets from point A to point B — and appetite. The team found that megalodons can reach speeds of more than three miles per hour, said Dr. Pimento, much faster than the 33 other sharks they surveyed. Among the sharks found, the fastest sailing speed belongs to the salmon shark, which can run about two miles per hour.
Given that the great white is slower It can travel nearly 7000 miles Without stopping to take advantage of seasonal prey, the team argued, the megalodon would likely have gone much further. In fact, she should have kept her food. While Fossil remains from Peru While megalodon occasionally hunts seals, “the shark’s large body size and potential energy requirements suggest that it will need high-calorie prey, such as whales,” Dr. Pimento explained.
Dr. Hutchinson noted that in modern ecosystems, large migratory animals play an important role in the flow of nutrients – deposited in dung or carcasses – around the world. As a trans-oceanic super predator, megalodon may have played a similar role in ocean ecosystems tens of millions of years ago, when sea levels were slightly higher than they are today.
But major predators are often uniquely vulnerable to a changing world. In the Pliocene, ice growth at the poles led to frequent sea level changes and the loss of important marine habitats. An accompanying extinction event led to a decrease in large prey, most likely Forcing the megalodon into direct competition with smaller sharks such as the great white. The last formidable predators disappeared three million years ago.
“It would be safe to assume that its extinction had global-scale effects on top-down food webs,” said Dr. Pimento.
So the team’s model indicates that the megalodon was not physically larger than previously assumed; It’s also possible that they played a larger role in ocean systems as well, making them poorer – albeit safer – for their passage.
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