A big part of the fascination with dinosaurs is how scary they are. What could be more terrifying than a pack of carnivore dinosaurs hunting you in an ancient forest or being attacked by an armored dinosaur swinging its tail at you? If a dinosaur is chasing you, the most terrifying dinosaurs had features and characteristics that would have made you feel even more frightened or fearful for your life.
The most terrifying dinosaurs are the ones that have the scariest jaws and teeth, the deadliest armor and weapons, and the size to go along with it. Match with that speed, aggressiveness, and even intelligence when hunting makes it even scarier and dangerous. One could argue that almost all dinosaurs had some characteristics that made them frightening, but it’s also true that some of the features, such as the size of the teeth or quantity, were more evident in some dinosaurs than others.
To put a frame around what is terrifying, or what creates fear when thinking about dinosaur chasing you in an ancient forest, let’s first consider a few ideas on the topic.
According to Wikipedia, “fear is an emotion induced by perceived danger or threat, which causes physiological changes and ultimately behavioral changes, such as fleeing, hiding, or freezing from perceived traumatic events.” It can be the fear of the unknown or the fear of getting hurt or killed.
With this in mind, let’s consider dinosaurs. What makes you terrified, when considering an animal or a creature like a dinosaur? It has a lot to do with outside appearances, like size, sharp teeth, sharp weapons, or perceived threat of danger to your life like something coming fast towards you, snapping jaws full of teeth, or even the thought of the dinosaur being as smart or smarter than you.
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Carnivorous and herbivorous dinosaurs were equally dangerous, and gigantic sauropods could knock the wind out of dangerous predators like the T-rex. Large sizes were only suitable for defense, and teamwork was best for hunting. Some of the smallest dinosaurs posed the most significant threat for prey.
The dinosaurs were an intimidating species, and the following are 13 of the most terrifying dinosaurs that ever lived and the ones that could cause the most amount of fear! So, let’s start.
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What’s the Scariest Dinosaur with Armor?
Imagine This Scenario – You are walking in the forest, and you come across some eggs. You go to investigate the eggs, and suddenly you hear something large with four legs coming fast towards you! It’s an armored dinosaur, and it thinks you are going to hurt its eggs. Get ready to dodge and hide.
The armored dinosaurs were scary in their own right, even though they are plant-eating herbivore dinosaurs and probably docile. However, if attacked, frightened, or if they felt their eggs or baby dinosaurs were being threatened, they had specific armor and weapons to protect themselves and their offspring.
Let’s check out these armored dinosaurs and see how terrifying they can be.
13. Ankylosaurus
Ankylosaurus herded in North America. It stood six feet high and 21 feet long. It weighed six tons despite its compact structure, and its bony formation made it as dangerous as a tank. It was heavily coated by collagen-reinforced scale-armor and had a massive club at the end of its tail.
This dinosaur is considered one of the most armored dinosaurs of all time, and a pack of raptors couldn’t rip its hard shell without suffering difficulties and wounds. Biting at its neck was challenging because of the two massive horns rising from the back of its skull. It was close relative to Stegosaurus, and they had the same defense mechanisms by using its tail. It used its hundred-pound tail club to break the knees and skulls of predators such as the T-rex, Giganotosaurus and Mapusaurus.
What Made the Ankylosaurus so Frightening? – Its 100-pound club at the end of its tail. The whipping action, combined with the force of the club weight, could severely injure you.
12. Stegosaurus
Stegosaurus was physically intimidating because of its armor plates that stood vertically along its entire back. It had a monstrous size and robust strength. At the end of its tail, this dinosaur had four spikes that were probably more devastating than the tail-end mallet of the Ankylosaurus, because they could pierce the skin of attacking dinosaurs.
The dinosaur’s spikes could grow up to three feet in length, and the momentum at which the dinosaur could swing its spiked-tail could probably injure a predator. These dinosaurs lived at the end of the late Jurassic period so that the predominant predators would be Allosaurs.
What Made the Stegosaurus so Deadly? – The four spikes at the end of its tail, which could swing either way and impale you. Although the vertical plates along its back were used for defense, it would also make the dinosaur look taller than it was.
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11. Pentaceratops
This herbivorous dinosaur weighed about six tons, was 26.1 feet long and 13 feet tall. It carried a massive weight for its bones in comparison to carnivores with the same length and height. Its body was massively muscular and armored, and it had three gigantic horns on the head to charge, pierce, and knockdown predators it would charge if they got too close.
The Pentacerateps had an extra advantage because its tail was equipped with spikes (found in some fossils), which made its rear attacks as fatal as its front charges. Its spiked tail made it a bit more dangerous than the armored Ankylosaurus. There are indications it herded in packs to increase protection of attacks by predators.
Due to its massive size and having armor and weapons from head to tail, the Pentaceratops is the most terrifying armored dinosaur in my view.
What Made the Pentaceratops so Terrifying? – Three horns and a frill shield, as well as a weaponized tail (found in some fossils). If it charged at you, it could spear you with its horns. If you tried to dodge it, you might meet its spiked tail.
If you are interested to learn more about armored dinosaurs, check out the article that I wrote about this topic – How Did Dinosaurs Protect Themselves? (Armor, Weapons)
Table 1 - Terrifying Armored Dinosaurs
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
|---|---|---|---|
 Ankylosaurus | Body armor and 100 lbs club tail | 5 | Armored |
 Stegosaurus | Vertical plate armor along back and spiked tail | 6 | Armored |
 Pentaceratops | 3 Horns on head, spikes on frill and spiked tail | 7 | Armored |
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
Could a Sauropod be Terrifying? The Most Terrifying Sauropod
Imagine This Scenario – You are in a marshy swamp, and you hear multiple Sauropods walking thunderously towards you. As they draw closer, you realize they are walking faster, so you try to run to the side of the herd. A booming sound, like a bullwhip cracking, fills the air. Your terrifying options – being trampled by a 15-ton dinosaur or being whipped by its giant tail.
10. Diplodocus
The Diplodocus was one of the longest dinosaurs, with arguably the longest neck and tail of any of the Sauropod dinosaurs. The longest fossil found measured 108 feet (33 meters) long. Diplodocus was a herbivore, which means it didn’t hunt for prey but instead ate plants. Scientists have suggested (Source) that because of the length of the tail, it was able to generate a whipping motion capable of making a loud cracking-boom sound as well as the possibility to inflict injury to attacking predators if got on the wrong end of that whiptail. The danger of getting stomped on or whipped by its tail qualifies it as one of the most terrifying dinosaurs.
What Made the Diplodocus so Frightening? – The possibility of being trampled by a giant Sauropod and the whiptail, which could probably have killed you if you were at the end of it.
Table 2 - Terrifying Sauropod Dinosaur
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
|---|---|---|---|
 Diplodocus | Giant size and long whipping tail | 6 | Sauropod |
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
What are the Most Terrifying Marine Reptiles Related to Dinosaurs?
Imagine This Scenario – You are in your sailboat on a prehistoric sea. The weather is hot, and the water is cool. You decide to take a swim. In the distance you see a large school of fish moving fast towards you. No panic. Except, now you see a giant marine reptile was the cause of why the school of fish was moving so fast. Now that marine reptile is coming your way too.
9. Mosasaurus
Mosasaurus lived during the late-Cretaceous period, and its fossils have been found on every continent, including Antarctica. It swam the oceans and was a prime predator with strong jaws. It was also a powerful swimmer and grew to about 4 meters, but the most significant fossils found were up to 13 feet. The Mosasaurs had jaws and teeth that were similar in shape and form to snakes, which meant that it could swallow prey whole without the need to bite it into chunks.
What Made the Mosasaurus so Terrifying? – Giant jaws with rows of teeth that swallow fish whole. Combine that with the Mosasaur being an agile swimmer too.
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8. Plesiosaurus
The Plesiosaurus was a predator of the seas and oceans, which was also a powerful swimmer with four large paddle-like flippers. What made this marine reptile different from a Mosasaurus is that the Plesiosaurus had a long neck ending in a small head with a “U-shaped” jaw that had rows of razor-sharp teeth. Its neck could be used to snatch fish, trying to get away from different angles. Plesiosaurus fossils have been found in England and other places in Western Europe, although a complete skeleton was found in England. It grew to a length of 4 meters to 15 meters.
What Made the Plesiosaurus so Terrifying? – Because it was a strong swimmer, it could catch you easily. But even if you made it to the boat, there is a chance that with its long neck could reach inside the boat and snatch you away.
Table 3 - Terrifying Marine Reptiles
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
|---|---|---|---|
 Mosasaurus | Agile swimmer with large mouth full of teeth | 5 | Marine Reptile |
 Plesiosaurus | Long neck that could reach you in a boat, head full of teeth | 5 | Marine Reptile |
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
What are the Most Terrifying Dinosaurs That Were Predators?
Imagine This Scenario – you are running in the forest, something is after you and suspect it’s a dinosaur. You try to hide under a big tree trunk that has fallen, and you think the dinosaur cannot see you. But the dinosaur is sniffing you out, and you’re just about to come face to face with it.
Carnivores were predators that hunted – either individually or in groups – and these dinosaurs had developed features to improve their hunting like razor-sharp teeth, claws, or even more developed noses or intelligence (bigger brains). Let’s take a closer look at the most terrifying dinosaurs that were hunters.
7. Utahraptor
The Utahraptor is the biggest and oldest among the raptors, and it weighed about a ton. It was almost five times the size of a Velociraptor, which is more well-known due to its portrayal in the Jurassic Park and Jurassic World movies. But the Utahraptor was much slower than its descendants and had a killer hind-leg and sickle-shaped toe claws that were razor-sharp and nearly 10 inches long.
These predators were much smaller than other dinosaurs of their ecosystems, but they hunted and killed much bigger predators than themselves and they can be considered one of the most terrifying dinosaurs. They benefited from speed, ferocity, and numbers. They were mostly feathered. Comparably, they were like gigantic, quick, carnivorous ostriches. Certainly, these were some of the scariest dinosaurs.
What Made the Utahraptor (and Raptors in General) so Terrifying? – They hunted In groups, were quick and agile, and their claws were developed for slashing and grabbing prey.
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6. Giganotosaurus
This giant dinosaur was the largest carnivore that lived in what is now current-day Argentina. Giganotosaurus lived during the Cretaceous period, and it weighed nine tons on average. Paleontologists have not been able to find a full fossil specimen to confirm its weight and height. Still, as it lived in South America, it is estimated that it may have hunted Argentinosaurus, which was probably the largest terrestrial Sauropod at the time.
It’s estimated that this carnivore was bigger and more towering than the T-rex. It was also more slender and could beat T-rexes in speed by at least 10 miles per hour. It was a well-adapted predator. The Gigantosaurus also fell short of the T-Rex in that it had half the brain capacity of the T-Rex.
What Made the Gigantosaurus so Terrifying? – The size of the dinosaur, with its teeth and speed, made it a vicious predator.
5. Mapusaurus
This monstrosity was similar in size to Giganotosaurus. Its fossils have been found in South America, in what is now Chile and Argentina. As such, it’s assumed that it hunted the Argentinosaurus. The 33-foot-long lizard weighed 3 tons, on average, and hunted in packs. Systemic hunting qualifies it on this list even though the individual Mapusaurus was not as intelligent compared to other predators. They could team up successfully to take down 100-foot long sauropods.
What Made the Mapusaurus so Terrifying? – This dinosaur hunted in packs or groups. All those terrifying jaws, teeth, and claws are coming at you from multiple directions.
4. Allosaurus
This dinosaur was the king of the food chain in the American Jurassic niches. It was 30 feet long and stood 12 feet high. This American dinosaur had over 60, D-shaped, sharp teeth that made its bite deadly and final. Despite its massive build, this species was light and fast: weighing an average of 850 pounds.
The Allosaurus lived during the late-Jurassic period and had become extinct by the time the bigger T-Rex and similar-sized predators existed. It’s often matched up for hunting for Stegosaurs and what a match that would be.
What Made the Allosaurus so Terrifying? – Its teeth, size, and aggressive predator instincts combined with hunting in groups. Dominant predator during the late-Jurassic period.
3. Troodon
The Troodon, a dinosaur that Paleontologists have found in Montana, is considered to be one of the smartest dinosaurs. It is because of the size of its brain. In comparison to other dinosaurs, Troodon’s brain was bigger, and scientists think that it had similar intelligence to modern-day birds. The dinosaur was a carnivore, although some scientists believe it could have also been an omnivore, which eats both meat (and insects) as well as plants. Troodons were fairly small, about 4 meters in length, but they also hunted in packs, which meant that multiple smart dinosaurs would be after you.
What Made the Troodon so Terrifying? – This dinosaur hunted in groups and was intelligent even if they weren’t so big. The idea that a dinosaur could be smart enough to figure out your next move is more than unsettling and earns its rank for being in the top 3 of the most terrifying dinosaurs.
2. Tyrannosaurus Rex
Let’s face it, if you came across a T-Rex and it started hunting you, it was your basic nightmare. The King of Dinosaurs was the ultimate killing machine, and it was robustly built. Weighing about seven tons on average, the T-rex could out-compete the Giganotosaurus within the same niche because of its wits. The predator stood over 16 feet tall and, according to some scientific studies, could run fast – a minimum of 18 km per hour up to 40km! If you are wondering why they are recognized as the king of dinosaurs, well, think about just how well-rounded they were. They were intelligent predators, almost as smart as raptors, and had extraordinary smelling abilities.
The T-rex had killing efficiency anchored in its 60, ferocious, saw-edged teeth and stronger jaws than that of any terrestrial predator. It only had to bite once to finish a kill on thickly-armored dinosaurs.
What Made the Tyrannosaurus Rex so Terrifying? – The teeth, jaw strength, and size of the T-Rex are enough to give anyone terrifying fear but add to that some intelligence, the large nostrils with the keen ability to smell prey and the speed to chase you and it adds up to a world of trouble!
What is the Scariest, Most Terrifying Dinosaur Ever?
1. Spinosaurus
Imagine This Scenario – Just like above, you are running in the forest, something is after you and suspect it’s a dinosaur. You try to hide under a big tree trunk that has fallen, and you think the dinosaur cannot see you. But the dinosaur is sniffing you out…except this time you see a big river or sea, and you decide to make a run for it.
With any of the other land predators, even the great T-Rex, by running into the river or the sea, you are safe from the dinosaur. But not with Spinosaurus, and that is the reason why my vote is given to this dinosaur as being the most terrifying dinosaur.
The most terrifying characteristic of this hunter is the fact that it could chase prey on land, knock down trees, and swim fast in deep waters. Trying to escape it would be difficult, if not impossible.
Chills run down my spine, I have to admit, when I think about this dinosaur chasing me. There was simply no way to escape from this monstrosity, and nothing could save you from this giant species of predator. This carnivorous dinosaur was 44 feet long and weighed about 20 metric tons. It could pull out great white sharks from water and kill them in single-bite attacks. As the largest land carnivore, according to current science, this dinosaur grew huge bones on its back that measured about 4-5 feet. I mentioned its ability to swim. Scientists think the huge bones on its back served as a kind of upper dorsal fin, which could help it maneuver even better in the water.
Why Was the Spinosaurus the Most Terrifying? – It could hunt on land and sea. No chance evading this dinosaur. It also is the biggest land carnivore and its large size made it one of the scariest dinosaurs ever to walk the earth. It had a crocodile-like head with the teeth to match, it was fast and agile on land and probably even more so in water. No escape from this dinosaur.
Table 4 - Terrifying Dinosaur Predators
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
|---|---|---|---|
 Utahraptor | Quick & aggressive, slashing claws, hunted in groups | 7 | Predator |
 Giganotosaurus | Giant dinosaur, huge teeth and speed on the ground | 7 | Predator |
 Mapusaurus | Terrifying jaws and teeth, hunted in groups | 7 | Predator |
 Allosaurus | Teeth, agile hunter, hunted in groups, dominant hunter in late-Jurassic | 8 | Predator |
 Troodon | An intelligent dinosaur, hunts in groups | 8 | Predator |
 Tyrannosaurus Rex | Teeth, jaw strength, agile, exceptional sense of smell and large size | 9 | Predator |
 Spinosaurus | Largest land carnivore, crocodile like head full of teeth, agile and can hunt equally well on land or in water | 10 | Predator |
| Dinosaur | Terrifying Features | Level of Scaryness Scale 1-10 | Category Group |
Final Thoughts
It’s fair to say that any of the 13 dinosaurs listed were terrifying in specific circumstances and enough to scare your socks off. Although we will never know what these creatures were really like, we can draw some parallels from modern-day animals like reptiles, lizards, and even mammals. That’s scary enough. Thank goodness I live in the city!
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