Archelon

We’ve seen large mammals, but what about large turtles? These extinct animals are the largest turtles to have ever existed. They weighed over 4,900 pounds, and measured around 16 feet from head to tail. That’s huge! Through evolution, modern day turtles have hard shells on their bodies, but the Archelon had a leather carapace. They existed around 100 million to 66 million years ago, during the Late Cretaceous epoch (Wikipedia).

Megalania

Monitor lizards are terrifying, but large monitor lizards that existed during the Pleistocene Epoch were even more frightening. Even though monitor lizards bite, their bites aren’t venomous or poisonous. Modern day monitor lizards only bite when provoked, so if you see one, your safest bet is to stay far away. These extinct animals wandered the earth roughly 2.5 million years ago, and were 7 meters long. This is the same size as a modern day Saltwater Crocodile. During the time of the Megalania, they were the largest lizards of their time (Dinopedia).

Andrewsarchus

These now extinct animals existed during the middle Eocene epoch, in what is now known as Inner Mongolia, China. They have a frightening, canine-like appearance. When you first glance at them, you’d think they’re related to wolves or dogs, but they’re more closely related to the hippo! They had hooves on their feet as opposed to claws. They were as tall as horses, and weighed about a ton. A discovery in 1923 found that their skulls were three feet long with huge teeth (Walking With Wikis).

Pentecopterus

These extinct animals belong to a group of aquatic arthropods during the Middle Ordovician period, which existed roughly 467.3 million years ago. These giant sea scorpions were predators of the prehistoric seas. It’s a genus of eurypterid, and contains only one species that surpasses the other eurypterids by 9 million years. Modern day sea scorpions aren’t dangerous, but can still cause a minor injury if you accidentally come into contact with one. If we existed millions of years ago and accidentally stumbled upon a giant sea scorpion, it might be a different story (Wikipedia).

Hallucigenia

During the middle of the Cambrian era, about 500 million years ago, the Hallucigenia existed. These now extinct animals were bizarre, and even though they were tiny – only 2 cm long – they were absolutely frightening. They had enormous spines and claw-like appendages, with a strange face that was only recently discovered.

Interestingly enough, Dr. Martin Smith, from the University of Cambridge, said: “It looks completely surreal. It is like something from another world.” They more closely resembled a caterpillar, because of its strange appendages, which were shown in the fossils, which were used as food-scavenging tentacles. It was believed they walked the earth on stilted legs. These frightening creatures aren’t ones we would’ve wanted to accidentally find outside or near our home! (Earth)

Edestus

These scissor-toothed sharks are now extinct animals that used to use vertical thrashing to kill their prey. New research discovered they had some seriously crazy external teeth, which they used to their advantage. Their jaw was similar to the Helicoprion, but their arc of teeth was on the floor and on the roof of its mouth. They used their highly curved whorls to subdue and eat their prey. These terrifying extinct animals were found around the world, in the United States, Russia, and the United Kingdom (Earth Archives).

Jaekelopterus

These large eurypterids originated in what is now Europe, 417 million years ago. Known as sea scorpions, these aren’t critters you would have wanted to accidentally step on. They were large, measuring up to 3.75 meters long. These extinct animals were also the largest arthropods to ever exist. Their long claws on the front of their body are definitely terrifying to look at (Pre-historic Earth).

Gorgonops

These extinct animals existed around 260-254 million years ago, during the Late Permian period. They grew up to 10 feet, and were some of the most ferocious predators during that time period. The Gorgonops were also some of the largest carnivores to ever exist, and they had up to 12cm long saber-like teeth, used for killing their prey. Their heads were also dog-like, and the largest known of the species was the size of a large bear, with a 45cm long skull (Dinopedia).

Megatherium

The Megatherium, which are now extinct animals, were some of the largest ground sloths to roam the planet. They were half the size of modern day elephants, and had terrifying claws and teeth. Even though they mainly fed on leaves of trees and bushes, their appearance wasn’t any less terrifying. They roamed the lands of South America during the Cenozoic Era, which began 65.5 million years ago. Interestingly enough, their name means “Great Beast from America.” We can agree that they looked like beasts (Britannica).

Meganeura

These frightening monsters were actually dragonflies, found in both Britain and America. They existed 300 million years ago, and were referred to as the “Queen of the Carboniferous Skies,” and had an impressive wingspan of up to 65cm. To put it into perspective, a one foot wingspan is about the size of an Eagle. Millions of years ago, we would’ve found these now extinct animals across the globe. You wouldn’t want one of them to spot you, as they would dive down from the sky and snatch you off the ground – dead or alive (Walking With Dinos).

Phoberomys

First, let’s picture a small, modern day rodent. Now, let’s picture the largest rodent to have ever lived. That’s Phoberomys, which are currently extinct animals that used to roam around our planet. They wandered the lands of South America during the Late Miocene, which was 11.6 million to 5.3 million years ago, and the Early Pliocene, about 5.3 million to 3.6 million years ago. More specifically, they lived in the Orinoco River delta. They had high-crowned premolars and were herbivores. Despite the fact they ate only plants, it doesn’t make them any less terrifying (Britannica).

Haast’s Eagle

Prehistoric eagles were vicious. They were relentless, and ate other birds. If you happened to spot flightless prehistoric birds, then there were certainly other predatory vultures or eagles in the area. In Pleistocene New Zealand, Haast’s Eagles would prey on juvenile, newly hatched moas, like Emeus and Dinornis. The adult Haast Eagles weighed about 30 pounds, which isn’t much of a difference than eagles today, which weigh about 20-25 pounds (Thoughtco).

Purussaurus

The Purussaurus, or “Purus Lizard,” lived about 10 million years ago, during the Miocene. These extinct animals were some of the largest crocodilians to ever exist, and were roughly 10 meters long. They also weighed 6 tons and were some of the most vicious predators in their environment. They hunted large mammals, in addition to the Megapiranha, which are extinct animals we saw earlier on this list (Additional Creatures).

Glyptodon

The Glyptodon were relatives of the armadillos that lived during the Pleistocene epoch. Surprisingly, these extinct animals were the size of a Volkswagen Beetle, weighing up to 1,850 pounds. It had squat limbs and a round, bony shell. It resembled the modern day turtle, and roamed the lands of North and South America. Their body shell alone was five feet. You wouldn’t want to mess with the Glyptodon, as their tails were equivalent to a lethal club. They devoured almost anything, including plants and insects (Wikipedia).

Megantereon

These extinct animals were discovered in 1824, and were a genus of the saber-toothed cat. They wandered the lands of Africa, Eurasia, and North America. They’re dated to about 4.5 million years. They mostly resemble the modern-day jaguar, with stocky forelimbs and strong neck muscles that could deliver a powerful bite. Some of their prey included horses and young rhinos and elephants. That just goes to show you how powerful these animals were, and are ones we wouldn’t want to run into. If it could devour an elephant, imagine what it could do to a human? (Dinopedia)

Liopleurodon

These large, carnivorous reptiles would’ve devoured us alive. Luckily, these now extinct animals no longer roam the seas, so we don’t have to worry while swimming in the ocean. They became extinct at the beginning of the Cretaceous Period, and were pretty deadly to other animals around them. It wasn’t until 150 million years ago when they went extinct, because a more vicious reptile emerged, the mosasaur, which ended up destroying the Liopleurodon (History of Yesterday).

Cameroceras

These extinct animals are giant orthoconic cephalopods, which inhabited the earth during the Ordovician period. They were first spotted 470 million years ago. They’re most similar to modern day squids, cuttlefish, and octopus. At the opening of a hard cone-like shell was their head, which was soft muscular tissue. They used their long, slithering tentacles to manipulate and capture prey. If we were alive millions of years ago, these are the types of tentacles you wouldn’t want wrapped around your foot in the middle of the ocean. Just look at how massive that animal is! Their toothed tongue would aid in devouring the flesh of their prey. We wouldn’t even have a chance if one of these captured us (Wikipedia)