But for all these assaults on the giant predator’s environment, it also benefitted from its success. The Megalodon shark was found worldwide – from Europe to Africa, North and South America, throughout Asia, Indonesia, and Australia. And it is well known that broadly distributed species were much better able to weather periods of significant change. Even under such altered conditions, a few populations could have (should have) adapted and survived.

Could it have? Let’s look at the evidence:

The case AGAINST:

Their habitat is now too different to support a mega-predator. For all of their great size they were shallow warm-water hunters, preferring depths of only about fifty to two hundred feet deep. Unlike their cousins the Great Whites, who liked deep and colder water.

Like the Great White they have row upon row of serrated teeth, designed to be discarded when damaged. We find Great White teeth embedded in whale carcasses all the time – why not Megs? The Megalodon’s bite power enabled it to shear through the heaviest bones and heads of its colossal prey. In the process it lost teeth that were quickly replaced. Where are the new ones? None, other than fossils exist. And where are the whale carcasses washing up with a ten-foot bite radius?

Great Whites only survived because they usually avoided Megalodon’s warm, shallow seas, perhaps in part to avoid ending up as their next meal. Instead, they lived in cool, temperate waters closer to the poles – which were warmer than they are now, and more like the sea environments they inhabit today.

So was the Megalodon disappearing good news for us humans? Maybe not – when you remove large sharks, then smaller predators become more abundant and they compete for the same fish stocks we humans live on. Less Megalodons, means more whales, but less fish for us.

The case FOR:

Don’t expect a Megalodon carcass to ever wash up – sharks don’t float, they have no swim bladder to inflate after death, so would sink. And if they had adapted to deeper water, then sightings would be rare (though there are a few pictures circulating on the web, I’d view these with suspicion).

But then again, something that big should eventually makes its presence known, or at least leave clues. Well, of course – numerous sightings, and not just by rum-soaked seaman or overenthusiastic fiction writers. Here are few pieces of evidence for consideration:

• In 1918 a Port Stephens’ fishermen refused to go to sea when an immense shark was taking the lobster pots (each around three feet across). This shark frightened the locals to the point where they refused to put to sea – this must have been something pretty substantial, as no fishing meant no food and no income. Many of the witnesses claimed the shark was over a hundred feet in length, and the monster hung around for weeks.