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Ancient terrors: Six MORE awful and thankfully long-extinct creatures

Daniel Martins
Digital Reporter

Sunday, June 29, 2014, 9:39 PM - The natural world is full of beautiful creatures, enriching our planet as they walk the Earth, swim the seas or fill the skies.

But among those wonders are the occasional terror. Fortunately for us, the most horrifying of those are largely extinct, to the great relief of anyone who ever becomes aware they ever existed.

We've talked before about five terrifying ancient creatures that now exist only in the fossil record. Here are six more.

Helicoprion had a buzzsaw in its mouth

So imagine you’re a paleontologist, hunkered down on some dig site, possibly humming a tune as you absentmindedly brush away at the dirt of ages, when this emerges beneath your brush:

Image: thesupermat / Wikimedia Commons

Image: thesupermat / Wikimedia Commons


This is one of those terrifying outliers that Evolution likes to cough up every once inawhile. It’s what’s known as the “tooth whorl” of Helicoprion, a shark-like creature (actually more like today’s ratfish) that lurked in the deeps 270 million years ago.

Yes, tooth whorl. Those are teeth. The creature itself is believed to have grown no more than 6 m, and usually 3-4 m, which, while horrible, isn’t too far beyond the pale, but the addition of that nightmarish buzzsaw in its chompers instantly rockets it into the realm of nightmare fuel.

Trouble is, the fossil record is so paltry, we didn’t actually know HOW something like this could possibly fit in something’s face. Scientists and artists came up with all kinds of crazy illustrations, like the one below, which puts it sort of jutting out.

Image: Dmitry Bogdanov / Wikimedia Commons

Image: Dmitry Bogdanov / Wikimedia Commons


Others actually imagined it looking like a serrated elephant’s trunk, or a toothy proboscis from some kind of hell-moth.

It wasn’t until quite recently that scientists at Idaho State University gave it a CT scan, and determined the actual set up would have been closer to this:

Image: Stanton F. Fink

Image: Stanton F. Fink


It seems out of that terrifying whorl, only around a dozen of the teeth would have actually been protruding during a shark’s lifetime. The rest, perhaps as many as 150, would be below the gumline, emerging slowly.

It also wouldn’t actually function like a buzzsaw, although the jaw’s movement would have created a saw-like motion to tear through Helicoprion’s prey, which is believed to have been softer fare like squid.

Still. Glad it’s extinct.

Jaekelopterus was underwater nightmare fuel

Like you needed another reason to never go anywhere near prehistoric oceans, here’s Jaekelopterus:

Image: GhedoGhedo / Wikimedia Commons

Image: GhedoGhedo / Wikimedia Commons


It’s a euryptid, which was a series of prehistoric, and hideously huge sea scorpions that used to prowl the shallows.

How huge? Well, scientists already knew they were pretty big, but the crusty beasts really upped their game when scientists discovered a 46-cm claw in Germany in 2007.

Without the full specimen on hand, they had a look at the claw, measured it against other claws and other individuals in the fossil record, then made a few calculations … and it turns out that claw likely belonged to a sea scorpion around 2.5 m long.

That’s larger than a human being. Heck, that’s about the size of a crocodile. In fact, that’s as large, if not larger, than most prime land predators on Earth today.

And back in the day (the claw is estimated to be 390 million years old), these sea scorpions would have ruled beneath the sea, having few real predators other than nautiloids, primitive cephalopods:

It would have used those claws to ambush prey, though fortunately it was much too large to crawl up on land. And anyways, its number came up when jawed fish began to develop, and thrive.

A 2.5 m long giant sea scorpion is hard to miss, so nature began selecting for smaller sizes … easier to hide that way.

There are no living sea scorpion species left. Nothing like a few hundred millennia to take the bite out of prehistoric terrors.

Meganeura was a bug the size of a hawk

So, that sea scorpion was pretty enormous, but have no fear! Taking to the skies at the end of the Carboniferous period, around 300 million years ago, you’d have found no bugs remotely that big.

No. The worst you’d have run into is Meganeura, a giant dragonfly with a 70 cm wingspan.

Image: GermanOle / Wikimedia Commons

Image: GermanOle / Wikimedia Commons

Honestly, that’s like not even three quarters of a metre! Surely we can live with that.

Meganeura would have pretty much dominated the insect food chain. Like other giant bugs we’ve written about here, it reached its ridiculous size due to higher oxygen levels in the atmosphere, around 35 per cent of the total rather than today’s 21 per cent.

They’re more correctly called “griffinflies” rather than dragonflies, but this source says they likely would have hunted about the same way as the latter, feeding on smaller insects. In fact, it may even have hunted small amphibians, which were emerging at the time.

We don’t like to think of any kind of insect large enough to feed on anything that’s not another insect, to be honest.

These days, actual dragonflies are more likely to be a meal for amphibians, rather than the other way around. We wonder if, every time a frog snags one of these with its tongue, it realizes it's fulfilling a revenge millions of years in the making.

NEXT: From horribly huge bugs to abominably big birds

Haast’s Eagle preyed on birds bigger than humans

That’s enough about hideously large insects. Let’s move on to hideously large birds.

Usually it’s Australia that’s famous for over-the-top dangerous fauna, but next-door New Zealand has its own contender for the crown of terrifying ancient animal.

See those running birds in the picture below?

Image: John Megahan / PLoS Biology

Image: John Megahan / PLoS Biology

Those are moa, huge flightless birds. They could grow taller than 3 m. That’s not our beastie, though. This entry is about what those huge creatures (which, we remind you, are larger than human beings) are running FROM: The Haast’s eagle.

With a wingspan of up to 3 m, and claws the size of a tiger’s, this enormous bird feared exactly nothing. When your main protein source is moa, chances are you’re at the top of the food chain (this source says it was the world’s largest eagle and the top predator of its eco system).

There may have been up to 4,500 breeding pairs of these things at their peak, so when the Maori people first arrived in New Zealand, the huge predators blotting out the sun must have been a bit of a shock to them.

This source notes Maori oral tradition says it was large enough to attack children. We’ll try not to think about how they found that out.

We don’t know what kind of luck the Maori had hunting the Haast’s eagle, but they had great success hunting the moa to extinction.

With the decline of their biggest food source, not to mention shrinking forests, the Haast’s days were numbered. They went extinct around 500 years ago, dooming people in New Zealand to a life of not having to be terrified of the open sky.

Megatherium was a sloth the size of an elephant

You know tree sloths? The cute ones, with super-slow metabolisms that can barely move when they’re out of their tree, and couldn’t reasonably be expected to harm another living being? 

Well … turns out their ancestors used to live on the ground. Also, they were the size of elephants.

Image: Lady of Hats / Wikimedia Commons

Image: Lady of Hats / Wikimedia Commons

Megatherium was also known as the “giant ground sloth,” which sounds like it should be a Monty Python punchline until you actually look at the size of the fossils we’ve found.

Up to 7 m long and weighing in at 2.5 tonnes, they thrived from Alaska to Patagonia until around 10,000 years ago. 

There are several theories about why they went extinct, but the top contender seem to be human impact, and an inability to adapt to climate change.

To people in the 18th and 19th centuries (and certainly to anyone happening upon such a massive skeleton), it would be easy to assume Megatherium would have been a carnivorous predator … provided you never got a good look at its jaw, which definitely looks like that of a herbivore.

In fact, although this article at details the sort-of-science behind the carnivore theory, this paper on the beasts’ dietary habits says most people always assumed they were herbivores – although the research it cites says it might have stooped to eating carrion if plants happened to be in short supply.

Image: Robert Bruce Horsfall

Image: Robert Bruce Horsfall

Still. Although likely no real threat to the humans of the time, we have trouble wrapping out heads around having "giant" and "sloth" anywhere in the same sentence.

Paraceratherium was the largest land mammal ever

While Megatherium lived relatively close to humans' time scale, the gigantic Paraceratherium – also known as indricotherium and several other names – died out around 23 million years ago.

Image: American History of Natural History

Image: American History of Natural History

As giants go, it’s the most giant of all, at least in mammalian terms. Standing 5.5 m at the shoulder and tipping the scales at 20 tonnes, it is the largest-ever land mammal, making mammoths look puny by comparison.

It was, of course, a herbivore. Although larger than an elephant, it was actually a kind of proto-rhinoceros, and ate leaves giraffe-like, with its long neck and, according to this source, a prehensile lower tongue.

Most people haven’t really heard about this beast, and even the ones who discovered it took a long time to even figure out what it probably looked like. Early versions made it look exactly like a rhinoceros, just three times the size and without a horn.

And of course, as a herbivore, its biggest threat to other species would likely have been through trampling, but the fossil record can’t really tell us much about its social behaviours.

We decided to put it on this list anyways, though. A gigantic prehistoric rhinoceros, harmless or not, still counts as terrifyingly huge.

Five scary-looking terrors from the deep
Five enormous (and thankfully extinct) ancestors of common species
Five pint-sized predators who fear nothing
From oblivion to buried treasure: Seven weird/scary/awesome holes

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