The resulting model suggested a 15 metre-long, 60,780kg animal, about as large as a whale shark. It is possible that other megalodons were even larger, Pimiento said; there are other fossilised vertebrae that are 50 per cent larger than those used in the model, suggesting a maximum length of 20 metres, which is longer than a modern humpback whale. The model megalodon's jaws could open wide enough to gobble a 8-metre orca in as few as five bites.
How reliable is such computer modelling? "These reconstructions work pretty well when applied to living animals whose mass we know, so they seem to be okay overall," Hutchinson said. That is true especially given the natural variations in size among individual animals.
But some researchers point out that the model relies 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 fins, remain speculative," said Kenshu Shimada, a professor of paleobiology at DePaul University in Chicago.
If the team's model is accurate, however, it has implications about the enormous predators' cruising speed — how fast an animal gets from point A to point B — and appetite. The team found that megalodons could hit a cruising speed of over 5km/h, Pimiento said, much faster than the 33 other sharks they surveyed. Among existing sharks, the fastest cruising speed belongs to the salmon shark, which can manage about 3km/h.
Given that the slower great white shark can travel nearly 11,265km without stopping in order to take advantage of seasonal prey, the team argued, the megalodon likely could have gone much farther. Indeed, it would have had to in order to keep itself fed. While fossil remains from Peru have shown that the megalodon occasionally hunted seals, the shark's "large body size and potential energetic demands suggest that it would need highly caloric prey, like whales," Pimiento said.
In modern ecosystems, Hutchinson pointed out, large migratory animals play an important role in the flow of nutrients — deposited in dung or carcasses — across the globe. As a transoceanic superpredator, the megalodon probably played a similar role in ocean ecosystems tens of millions of years ago, when sea levels were quite a bit higher than they are in the present day.
But apex predators are often uniquely vulnerable to a changing world. In the Pliocene Epoch, the growth of ice at the poles led to frequent sea level changes and loss of important offshore habitats. An accompanying extinction event led to a decline in large prey, likely forcing the megalodon into direct competition with smaller sharks like the great white. The last of the enormous predators disappeared 3 million years ago.
"It would be safe to assume that its extinction had global-scale impacts on food webs from the top down," Pimiento said.
The team's model therefore suggests that the megalodon was not just physically bigger than previously assumed; it also probably played a bigger role in ocean systems, too, leaving them poorer — if safer — for its passing.
This article originally appeared in The New York Times.
Written by: Asher Elbein
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