This week you can go to the cinema and see Jason Statham take on a giant prehistoric shark. The Meg sees the action star face off against a Megalodon, a long-extinct shark far larger than today’s great whites.
The film looks gloriously silly and is expected to do well at the box office, partly because it seems to have embraced the inherent daftness of its premise. Unlike Jaws, which featured a living species of shark – albeit with an uncharacteristic taste for human flesh, rather than seal – The Meg is the Jurassic World of shark movies.
That’s a good thing. Unlike Jaws, The Meg is unlikely to scare anyone out of the water or encourage a “kill them all” attitude towards sharks – many of which are threatened species in need of protection.
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For an extinct creature, Megalodon gets a lot of press, which gives the impression we know a lot about it. We don’t, says palaeontologist Darren Naish of the University of Southampton, UK.
Pretty much all we have is teeth, which are startlingly big. “The record is 16.8 centimetres from base to tip,” says Naish. Otherwise, their bodies have not been preserved. Being sharks, their skeleton was made of cartilage rather than bone, which doesn’t fossilise. There are a few vertebrae, which were bonier than the rest of the skeleton, but that’s all.
Mystery monster
As a result, even something as basic as how long they were is an estimate, derived by measuring the teeth. The shark in The Meg is apparently “75 to 90 feet” or 22 to 27 metres, which is an exaggeration. “Current thinking is that it’s around 15-20 metres,” says Naish. Reconstructions of their jaws as large enough for a person to sit inside for a photo opportunity are also exaggerated.
Regardless, Megalodon was a whopper and would no doubt polish off Jase for breakfast. Great white sharks top out around 6 metres, and even blue whales, the largest animals ever, don’t get much beyond 30 metres.
The lack of bones means we don’t know what they looked like, or where they fit into the shark family tree. “It’s somewhere within the group of sharks called the Lamniformes,” says Naish. Also known as mackerel sharks, this group includes great whites and many other species including basking sharks, megamouth sharks and goblin sharks. It’s not clear where Megalodon fits: people have imagined it as a huge great white, but “that might be wrong”. Accordingly, there is no consensus on the scientific name.
However, we do know what Megalodon ate. “There’s bite marks on whale and dolphin bones that come from the right time,” says Naish. “It does seem to have been a marine mammal predator.” That’s to be expected, as it’s what great white sharks eat.
And there is one other remarkable finding. “This species used shallow-water ecosystems like the Panama Bay as a nursery,” says Catalina Pimiento of Swansea University, UK.” Unusually small Megalodon teeth from this region seem to belong to juveniles, which stayed there until they were big enough to hunt in the open sea.
Gone for good
Despite what some people say and a daft Discovery Channel mock-documentary claimed, it’s extremely unlikely that there are Megalodons lurking in the sea today.
They went extinct at least 2.6 million years ago, according to a study co-authored by Pimiento, who has spent ten years figuring out what happened. One issue seems to have been the evolution of new competitors like great white sharks and orcas, which meant the once-widespread Megalodons struggled to get enough food.
But the big reveal came in 2017, when Pimiento’s team discovered that Megalodon was only one victim of a hitherto-unknown extinction event in the sea. Among large marine animals, “36 per cent of all genera became extinct around the same time,” says Pimiento.
The key factor seems to have been changing sea levels, which reduced the volume of shallow, coastal waters – Megalodon’s hunting grounds. “We proposed that that reduction in area caused the extinction, because the animals didn’t have enough space to find food,” says Pimiento.
Lurking in the depths
People have offered two lines of evidence for Megalodon’s survival, says Naish. Certain teeth were claimed to be just 10,000 years old, for no good reason, and there have been a few sightings. Naish and co-authors examined these for their book Cryptozoologicon and found they “are either just tall tales or hoaxes, or they’re mistakes”.
There are surely plenty of marine species waiting to be discovered, including some big surprises, but they are likely to dwell in the deep sea. The megamouth shark was only discovered in 1976 because it lives in the depths.
Megalodon doesn’t fit this profile. “This is a surface-dwelling coastal shelf predator of big mammals,” says Naish. “Are you telling me that throughout the whole of history we don’t have any evidence?”
The evidence should be easy to come by, because sharks shed teeth constantly and Megalodon teeth are 15 centimetres long. “They’re really difficult to miss.”
American Museum of Natural History