Deadly Animals You’ll Be Glad To Know Are Extinct

Here are some dangerous prehistoric animals you'll be glad to know are extinct!

June 8, 2023・

21 min read

The world’s full of some terrifying creatures who’d have no trouble making a quick meal out of us humans! But as scary some animals today may seem, there once existed even bigger, badder, and way more terrifying beasts. From child-eating eagles to colossal carnivorous whales, here are some deadly beasts that you’ll be glad to know are extinct.

Arctotherium Angustidens

Stumbling across a grizzly bear is enough to make most people flee in fear. But even full-grown grizzlies look as harmless as cubs when compared to the Arctotherium Angustidens.

More commonly known as The Giant Short-Faced Bear, it hailed from South America and lived around 2.5 million years ago. With an average weight of 2 tons, Arctotherium Angustidens takes the title for Biggest Bear to Have Ever Lived!

For some context, polar bears, the largest land carnivore alive today, are less than half the weight of these ancient bears. On top of that, these guys could reach an intimidating 14 feet when stood upright, that’s higher than a one-story building!

They were really tall and really heavy, but that didn't slow them down. Considering that the close relative of this bear, the Arctodus Simus, a smaller genus within the giant short-faced bear family, could reach a terrifying top speed of 40 miles per hour, it’s likely that these guys would’ve clocked up a speedy pace too!

So, unless you’ve got wheels and an engine, there wouldn’t have been much chance of escaping! And escaping is definitely what you’d want to do. Broken fossilized teeth revealed that this bear chewed on bones, suggesting that flesh was a part of their diet. So, to them, human probably equals meaty appetizer.

Despite their physical prowess, these bears were gradually replaced by the medium-sized Arctotherium Vetustum around 500,000 years ago.

No one knows how or why such a predatory power disappeared, but it’s possible that the increased competition from carnivores like the jaguar, cougar and dire wolf depleted the big bear’s banquet. Either that, or there’s an even bigger bear out there that we just haven’t discovered yet.

Haast’s Eagle

Fortunately, those bulky bears went extinct around 400,000 years before us Homo Sapiens first appeared. However, some long-extinct animals once did go toe-to-toe with man. Or technically, toe-to-claw, if the large skeletal remains of the carnivorous Haast’s Eagle are anything to go by!

These particular remains were found in the South Island of New Zealand. With a wingspan of up to 10 ft, the remains are so large that the bird is now considered to be the biggest eagle ever! The skeleton indicated it would have stood around half the height of an average man, and weighed in at some 40 pounds, four times that of a bald eagle!

The main prey of these enormous eagles were Moa, a flightless bird that was 15 times heavier than their hunter. Moa bone remains show that Haast’s Eagles killed their prey by flying at them from behind and tackling them with their knife-like 3-inch talons, before gripping and crushing the Moa’s skull!

Disturbingly, it's possible that Moa wasn’t the only meal on the Haast’s Eagle menu. Legends from the indigenous Māori people of New Zealand detail huge birds, swooping down and plucking up a small child, who was never to be seen again.

But in the 16th century, just 200 years after the Māori population settled on the South Island, they got their revenge. Human overhunting of the Moa likely led to the eagle’s eventual extinction. And with that, Māori children could finally rest easy!

Josephoartigasia Monesi

New York is famous for its massive rats, with some reaching the size of small dogs and house cats! But as big as a New York rat may be, their ancient cousins were something else. Introducing, the Josephoartigasia Monesi, who lived way back between 4 to 2 million years ago.

Considered to be the largest rodent to ever walk the face of the earth, these South American horrors measure in up to 10 feet long and weighed a whopping 2,200 pounds. For some perspective, that’s around the same weight as 12 adult humans!

Size isn’t the only thing to watch out for with these mega-rats, though. They also bared horrifying incisors, reaching almost an entire foot long!

Computer modeling techniques based on the Josephoartigasia Monesi’s skull revealed that the rodents had a bite force of 3,600 pounds per square inch, or PSI, giving them a similar bite force of a saltwater crocodile. Thankfully, these colossal rodents weren’t carnivorous killers.

Scientists believed that Josephoartigasia Monesi used their incisors for biting nuts and wood, digging in the ground for food, or defending themselves from predators. And with those giant horrors in their mouth, anything that messed with these guys would be sliced up in seconds.

Megalania

About 2.5 million years ago, the dusty plains of Australia were home to some real terrors, but none could compete with the giant monitor lizard, known as Megalania.

Looking like a hulked-out version of a Komodo dragon, these prehistoric predators could reach a whopping 23 feet long, making them more than twice the size of their Komodo descendants. And, like Komodo dragons, Megalania are believed to have harbored venomous glands inside their jaw, that produced hemotoxin.

When it attacked, Megalania’s sharp, curved teeth would pierce their prey’s skin, before the hemotoxin entered the victim’s bloodstream. At this point, the venom would act as an anticoagulant, preventing the prey’s blood from clotting! This, in turn, would rapidly decrease the prey’s blood pressure causing systemic shock, and eventually death.

So, what caused the downfall of this super-massive lethal lizard? Researchers from the University of Queensland recently dated a Megalania bone to be around 50,000 years old, which is around the same time that humans first arrived in Australia. It’s now believed that humans could have had a hand in the Megalania’s extinction.

Whether man killed the giant lizards to protect themselves, or over-hunted their prey isn’t known. What we do know, though, is that somehow Australia, the land where just about everything can kill you, could’ve been even more terrifying!

Thylacoleo Carnifex

Australia’s prehistoric horrors don’t end with Megalania! The Thylacoleo Carnifex, is an extinct marsupial lion that dominated the Australian wilderness between 2 million and 46,000 years ago.

Fossil evidence shows this wombat-lion hybrid measured in at around 5 feet long, about 2 ½ feet tall, and weighed around 220 pounds. This means that at their largest they were about the same weight as a modern jaguar, but slightly stockier!

However, unlike jaguars, Thylacoleo carnifex weren’t equipped with sharp canine teeth. Instead, these monstrous marsupials had two pairs of giant incisors that they used to stab and pierce the flesh of their prey.

And it was quite the stab! Their bite force was comparable to that of a 500-pound African lion. This is thanks to their enormous jaw muscles, which turned every tooth in their mouth into a weapon!

While their incisors were used for piercing the flesh of their prey, their molars were designed to crush their victim’s windpipe and sever their spinal cord. If that wasn’t bad enough, these menacing marsupials had huge retractable thumb claws, used for disemboweling their kill.

This metal hunting method would’ve helped these marsupial lions to kill large prey in less than a minute, 15 times quicker than an African lion. But, as with the Megalania, their ferocious features couldn’t prevent them from falling into extinction thanks to climate changes, which gradually dried out their habitat and reduced the food supply.

Gigantopithecus Blacki

Prehistoric primates, known as Gigantopithecus Blacki, that closely resemble bigfoot, roamed the forestland of Southern China roughly 2 million years ago. Exact size estimates are highly speculative because only teeth and jawbones have been discovered.

But even the existing evidence is enough to estimate that they stood around 10 feet tall and weighed up to 1,200 pounds, making them about twice as tall and nearly three times as heavy as silverback gorillas!

Being located in Southern China, it’s likely that bamboo was a staple of its diet. Still, you wouldn’t mess with these things, considering that even a silverback gorilla is strong enough to pummel a human into mincemeat. But what caused such a big, broad beast to go extinct? It's mainly because it was too big and broad.

The Gigantopithecus Blacki relied on chowing down on heaps of food to replenish itself. But, around 100,000 years ago, the changing climate transformed more and more of its forested homeland into savanna-like landscapes, greatly reducing the food supply for these primates.

Daeodon

Pigs nowadays are mostly harmless but that has not always been the case. If we turn the clocks back 23 million years, Daeodon, or ‘dreadful pigs’, were wreaking havoc in North America.

This brute came in at a massive 1,650 pounds, stood nearly 6 feet tall at the shoulder, and was 10 feet long, giving it a rhino-like build. However, unlike rhinos, these guys didn’t stick to eating vegetation.

If you look at their skull, their forward-facing eye sockets are designed to keep track of the prey they’re chasing. These pigs were predators! Recent research suggests that due to their lack of claws, they took down their prey by running alongside it, before ramming into it with brute force.

To make matters more disturbing, these powerful piggys also came with canines that were some 10 inches long, designed for ripping flesh to pieces! Scientists believe that Daeodon eventually went extinct around 20 million years ago, due to increased global temperatures, depleting both vegetation and prey animals.

Spinosaurus

If you mix a crocodile with a T-Rex it’d probably look like a Spinosaurus. Reaching lengths up to 59 feet and weighing a colossal 22 tons, this bulky beast is considered to be the largest carnivorous dinosaur to have ever walked the earth.

But their meal preference wasn’t usually terrestrial animals. Researchers believe that these dinos, hailing from North Africa, were water dwellers that mainly snacked on a feast of fishy food, including giant coelacanths, sawfish, and lungfish.

To help with this specialized diet, Spinosaurus evolved a long crocodile-like snout, packed with horrifying, six-inch-long conical teeth, adapted for piercing slippery fishy prey!

It's not known exactly what the sail made up of spines protruding from its vertebrae was used for, though it’s theorized it could have acted like the dorsal fin of a fish for stability in the water! But around 90 million years ago, global warming dried up the North African marshlands. And, with their fishy feast gone, these giants weren’t able to adapt to eat other prey.

Purussaurus

Crocs may look daunting enough as it is, but they’re nothing compared to the Purussaurus. This ravenous river giant once measured in at a head-spinning 35 feet long. That’s the same size as a school bus, and it was twice as long as a saltwater crocodile!

Unsurprisingly, it needed to eat a lot. Purussaurus went through roughly 90 pounds of food daily, twenty times the requirement for the modern American alligator! And, if you’re wondering what exactly Purussaurus ate, the simple answer is anything. From car-sized Stupendemys turtles to giant ground sloths, the world was their buffet.

Luckily for them, their insatiable appetite was helped by their powerful bite. Paleontologists calculated that the Purussaurus’ bite was equivalent to exerting 11.5 tons of pressure, giving it a bite 20 times stronger than that of a great white.

Utahraptor

If you’ve seen Jurassic Park, you’ll know just how scary Velociraptors once were! But they’re actually the smaller cousin of Utahraptors. These bird-like dinosaurs date back 125 million years, and stood up to 18 feet long, making them the length of a standard shipping container, but with a killer instinct!

To help with that killing, they came armed with a 15-inch claw on each foot. Just one kick from this bad boy was capable of slicing through an animal and it wouldn't be an easy task to run from these guys. Based on their slender legs and the speed of dinosaurs of similar sizes, it’s believed that Utahraptors could run up to 30 miles per hour!

Although fossilized feathers haven’t yet been found with Utahraptor bones, paleontologists are confident that they had them based on feather preservation in related dromaeosaurid species. So they're pretty much like giant, rapid, murderous chickens.

Smilodon

Diego, the Sabretooth cat from the endless series of Ice Age movies, may look cuddly on screen, but trying to snuggle up to a real Sabretooth cat would have left you with some serious scars!

Smilodon, the most famous of the Sabretooth cat species, lived in the Americas some 2.5 million years ago. The 8-inch, fang-like teeth sticking out these big cat’s mouths look utterly terrifying, but these upper canines aren’t believed to have packed much of a punch.

Computer scans of the fossilized skulls of sabretooth cats revealed that they generated a biteforce of just 220 pounds, which is only slightly stronger than a human bite. To make up for this, the Smilodon had proportionally longer front legs and a much more muscular build, compared to big cats today.

This would’ve helped them wrestle prey to the ground WWE style, before pinning their head down and making a precise bite to the throat with their curved canines. But ferocious fangs couldn’t save the Smilodon from the effects of climate change and humans, who overhunted the cat’s prey, eventually leading to its extinction 10,000 years ago.

Megapiranha

Walking on prehistoric land would have been scary, but swimming in the rivers would have been way worse! Around 8-10 million years ago in the Late Miocene, you would’ve had the horror of coming across Megapiranha in the rivers of South America.

And, as the name suggests, these famously carnivorous fish were huge. They grew to an alarming 28 inches, over 2 ft long, more than double the size of modern piranhas! They weighed around 22 pounds, making them 4 times heavier than the existing feisty fish!

But size isn’t the only thing that made these fish scary. Based off the bite force of living black piranhas, scientists estimate that the Megapiranha would’ve chomped down with a staggering force of 1,000 pounds of force. That would give its bite the same whack of that of a small great white shark, despite the fanged fish only weighing one fortieth of a great white.

Cameroceras

We know that wading in prehistoric waters would have been a bad idea, but it can always get worse, thanks to the ancient, alien-looking Cameroceras!

Cameroceras lived during the Ordovician period, some 470 million years ago and was an early cephalopod; a type of mollusk classification that includes the more familiar octopus, squid and cuttlefish. The eye-catching feature of this quirky character was its immense 36-foot-long shell, used to protect the Cameroceras main body.

But, being a carnivore, how exactly did this thing hunt? Despite their size, it’s believed that these cephalopods would lie horizontally, patiently waiting for a victim. Then, when a marine meal came close enough, they’d quickly ambush it. With their 3-foot-long tentacles, it pulled prey into its massive maw, much like modern cephalopods.

After hauling in its catch, like trilobites and sea scorpions, it would crunch their exoskeleton with its hard keratinous beak, before rasping out soft tissue from within the prey’s shell. The reign of the Cameroceras was brought to an end around 443 million years ago, when the Late Ordovician mass extinction eliminated nearly 85% of all marine species.

Megatherium Americanum

Sloths might be pretty small and cute but, astonishingly, their ancestor Megatherium Americanum is the opposite of them in almost every way. These giant sloths wandered through South America between 400,000 and 8,000 years ago.

They stood at an imposing 12 feet tall, and weighed in at a hefty 4 tons, around the same weight as an elephant. And, if that wasn’t bizarre enough, it’s likely that Megatheriums were hairless to prevent them from overheating.

To make matters even worse, they came with 7-inch claws. But scientists don’t believe that Megatherium were carnivorous; instead, it’s likely that their claws would’ve been used to swipe down tall vegetation.

While it’s currently not clear whether their diet included some meat, it is possible that they occasionally scavenged off carcasses. Some theories go even further, speculating that Megatherium would actively hunt smaller herbivores by flipping them over and slashing them open with its claws.

But incredibly, scientists believe that humans actually hunted these beasts! A killing site in Argentina revealed that around 12,000 years ago, a group of humans hunted and killed a giant sloth before leaving the animal’s bones behind along with their butchering knife.

In the end, human hunting and the effects of climate change depleted their vegetation food source and wiped this mega-sloth off the face of the earth!

Therizinosaurus

The ground sloth may have had some long claws, but those are nothing compared to what the Therizinosaurus sported. The scythe lizard, as it was known, lived in Asia some 70 million years ago and could grow to a gangly 16 feet tall.

But the most terrifying thing about the Therizinosaurus wasn’t its height, but its lengthy claws. These bad boys stretched over one and a half feet long, making them the longest claws of any animal ever! When these guys weren’t impersonating Edward Scissorhands, they were using their lengthy appendages to pull vegetation within reach.

Despite their crazy claws, it's believed that they were strictly herbivores, though someone forgot to tell that to the makers of Jurassic World: Dominion. This is down to their bipedal stance which, similar to other herbivores of the time, helped them reach further up into trees.

Even still, you wouldn’t want to get into a fight with one of these things flailing their death claws at you! Sadly, for them, the Therizinosaurus is believed to have perished in the K-T mass extinction event.

Platybelodon

Some prehistoric animal ancestors look pretty weird, and that’s definitely the case with the Platybelodon! This giant mammal lived in Asia, Africa and North America between 20 million and 8 million years ago. They’re a genus of larger herbivorous proboscidean mammals related to modern day elephants!

But alongside their trunk, Platybelodons had a strange jaw that jutted out underneath. Fitted on the base of this lower appendage were a pair of widened tusks, which acted as modified incisors. The key question is, what’s the use of having a spork fitted to your mouth?

It’s been repeatedly imagined as the lower half of an extended mouth, housing a long tongue. But, in 1992, paleontologist David Lambert theorized that the Platybelodon fed on plants and branches by cutting them away with their handy tool.

They may look more funny than threatening, but modern elephants already kill up to 500 humans every year, and that’s without a fleshy spork hanging from their mouths. Who knows what damage these elephant-adjacent animals could do using that curious cutlery appendage?

Quetzalcoatlus

The Quetzalcoatlus was a flying reptile which was alive some 70 million years ago. And, after learning about these winged nightmares, you'd wish they’d lived even further back in time. There aren’t many things more terrifying than the prospect of having a 16-foot-tall reptilian stork hunting you down.

These terrors also came with a 36-foot wingspan, making it the largest flying creature ever! For some context, the biggest wingspan found today is the 12-foot reach of a wandering albatross.

Quetzalcoatlus fossils were found on land, 250 miles away from coastlines, with no indication of any large rivers or lakes nearby during the Cretaceous period, in which they lived.

Instead, it’s believed that these birds chowed down on land animals. Their long, thin chopstick-like jaws made them effective at pinpointing and plucking up smaller dinosaurs and swallowing them whole!

These guys died off along with the Therizinosaurus during a mass extinction event 66 million years ago. So, luckily, we don’t have to watch out for any giraffe-sized flying reptiles trying to guzzle us down today!

Rhamphorhynchus

But the winged nightmares aren’t over! Another flapping fright is known as a Rhamphorhynchus, a flying reptile that soared the skies of Europe and Africa, between 154 and 137 million years ago.

Unlike the Quetzalcoatlus, these guys weren’t blessed with great size. Their wingspan was about 6 feet long, while their total body length was only 20 inches long, making them pigeon-sized, albeit with wider wings.

But what they lacked in size, they more than make up for in terror, because the jaws of Rhamphorhynchus were filled with needle-like teeth. It may look like they lost a fight with a thorn bush, but these terrifying teeth served an important purpose. And that purpose was to help these ravenous reptiles catch fish by dip-feeding.

When the Rhamphorhynchus saw its prey, it would swim just above the water and lower its spiky bill in, impaling and catching the super slippery fish in the process. And, with the prey skewered, the Rhamphorhynchus would’ve swallowed it down in one. If these guys ever miraculously come back from extinction, just remember to never hand feed them!

Livyatan

We’ve taken a deep dive into some of the more terrifying things you can find in the water, but visually, very few are as terrifying as the Livyatan. This 55-foot-long genus of carnivorous sperm whale ruled the oceans off South America around 9 million years ago.

If its size alone wasn’t daunting enough, they were also fitted with more than 40 1-ft-2-inch-long teeth on their upper and lower jaws. With these, they could easily tear apart their prey, giving them the largest biting teeth of any animal to have ever lived!

Unsurprisingly, Livyatan ate pretty much any large marine life, but their go-to meal was 20-to-30-foot baleen whales. And for all their teeth, it’s believed that these murder busses hunted with their foreheads. They would’ve approached their prey from underneath, before smashing into them, like a battering ram, paralyzing their meal in the process.

But that fat forehead may have served another function too. As with modern sperm whales, the Livyatan is believed to have had a spermaceti organ. Presuming that it has the same function as it does today, these carnivores would’ve used it to emit high frequency sounds, acoustically stunning their prey.

Eventually, the intense sound exposure would shut down the bodily functions of the target! The Livyatan went extinct over 5 million years ago, due to a cooling event at the end of the Miocene Era, causing a reduction in their food population.

Megalodon

If you thought nothing could beat the might of the Livyatan, let me introduce you to the Megalodon, a species of mackerel shark that puts Jaws to shame. This 50-foot-long fish was over 3 times the length of a great white shark!

And these beefy boys were heavy too, weighing in at around 70 tons, which is equivalent to roughly 10 elephants! On top of that, their jaws could span over 6 feet wide, easily enough room for an entire human.

Furthermore, inside their maw you’d find 276 gigantic 7-inch, razor sharp teeth, primed for tearing apart prey. If that wasn’t enough, these mega sharks are estimated to have had a bite force of 40,000 pounds per square inch. That’s 10 times more powerful than the bite force of a great white!

Swimming throughout the world’s oceans between 20 million and 3.6 million years ago, they would’ve had to compete with the jumbo-sized Livyatan for food. If they did fight, you’d expect The Meg to make a decent dent in Livyatan’s blubber.

However, the whale’s slightly bigger size and ingenious use of acoustic stunning may have given it an edge. But who knows? One thing’s for certain, The Meg would eat a human up like a sardine!

So, how did this mega predator go extinct? The climate changed dramatically around 3.6 million years ago; temperatures dropped, and as a result, the warm-water areas where the sharks thrived became reduced, eventually leading to this genus’ extinction.

If you want to find out more about the Megalodon, I made an article specifically about Megalodon facts! I hope you were amazed at these dangerous prehistoric animals! Thanks for reading!