Excavations conducted by archaeologists unravel mysteries of the ancient past that baffle our minds. The fossils that are recovered from around the world tell us more about the dangerous creatures that lived before our time and now, thankfully, are extinct. When we talk about prehistoric creatures, the first thing that comes to our minds is the dinosaurs, but there were many others that lived in the same era and often preyed upon them.

When you read about these prehistoric creatures, you are going be thankful that you live in this time. Even the most terrifying creatures that exist today would appear timid in front of these.

1 The “Titanoboa” was a 42-foot-long, 2,500-pound snake that lived about 65 million years ago. Twenty-eight fossils of this largest and extinct species of snake were found in a coal mine in Colombia.

As if snakes were not scary enough! Imagine a 42-foot-long snake that lived in forests. This extinct species of huge snakes lived in what is now known as La Guajira, a part of northeastern Colombia, 58 to 60 million years ago in the middle- to late-Paleocene Epoch.

Multiple fossils of this snake were found at the Cerrejon Formation in Colombia, making it the largest snake ever discovered. It survived in the coastal swamp areas and was a piscivorous (a carnivore that eats only fish). A full-scale model of the Titanoboa was displayed at the Grand Central Terminal in New York when the Smithsonian Channel was to air a TV show titled Titanoboa: Monster Snake in 2012. (source)

2 A massive ancestor of the crocodile, “Deinosuchus” was around 10 to 12 meters long. Paleontologists concluded by studying its teeth marks on other fossils that it killed and ate some of the most fearsome dinosaurs of its era, including T-Rex.

In 1858, the first fossils of Deinosuchus, the name that literally translates into “terrible crocodile” were discovered in the western United States. With its robust teeth that could easily crush a skull, the crocodile could devour an entire Tyrannosaurus. It was most likely an apex predator of the Cretaceous Age. It would live up to 50 years of age and would continuously grow until the age of 35.

Researchers assume that if the massive crocodile ate dinosaurs, it would attack them when the dinosaurs would come to drink water. The Deinosuchus would catch them off guard and trap them in its jaws, drag them into the water, and drown them before eating them. The teeth marks of this prehistoric creature were also found on the shells of large turtles which meant it feasted upon them too as they were easily available in its habitat. (source)

3 “Megatherium” was a species of elephant-sized ground sloths that excavated hundreds of miles of tunnels in South America that exist until today. They lived until the end of the Pleistocene Age and could have been as long as 20 feet from head to tail.

Very few other species exceeded the size of the Megatherium. The first fossil of this giant sloth was found in Argentina in 1788 which was before the discovery of dinosaur fossils. Researchers have put forward a hypothesis that the sloths had giant claws and used them to dig tunnels.

They migrated from South to North America and lived until the end of the Pleistocene Age when they reached the size of an African elephant. They were herbivores that used their tongues to differentiate and select what foliage to eat in their grassland and woodland habitat. The Megatherium lived mostly in groups but could have also lived alone in caves at times. Many think that a contributing factor for its extinction were human hunters. (1, 2)

4 “Beelzebufo” was a species of prehistoric frog measuring up to 9 inches long with a very large mouth and strong bite force. It was a predator that feasted upon large creatures and baby dinosaurs for which it is also called  “devil frog.”

In the late Cretaceous Period some 70 million years ago, lived a prehistoric frog that has now been nicknamed the “devil frog.” Some estimates suggest that the frog could have measured as high as 15.7 inches with a very large head. The frog lived in what is now known as the country of Madagascar.

It is known to have preyed upon baby dinosaurs and other big animals using its large jaws. In 1993, the first fossil of the frog was found, and so far, 75 have been collected which has enabled the researchers to reconstruct the frog’s skull. Its closest living relatives are the horned toads of South America. (source)

5 The species of a pre-historic creature named “Jaekelopterus rhenaniae” was a fearsome water scorpion that was more than eight feet long with an 18-inch-long claw. It is the largest known arthropod to ever exist.

Although Jaekelopterus are also called “giant sea scorpions,” their remains have been found in freshwater systems and estuaries as well. It is the largest known arthropod and the largest known eurypterid to ever exist. The mouth of the scorpion had denticles of multiple sizes which allowed them to cause puncture wounds and would have made them apex predators in their environment. They would eat smaller arthropods, fishes and early vertebrae.

The Jaekelopterus lived in the darker, deeper levels of the sea and water bodies and would come near the shore to spawn and mate. It thought to have been highly agile and have quick maneuvering abilities which helped it give a chase to its prey. (source)

6 The “Megalodon” shark could bite down on its prey with a force of 24,000 to 41,000 pounds which was enough to crush the skull of the other whales it ate. If it opened its jaw, two humans could fit inside. The size of this dangerous creature was 79-82 feet long.

Based on the size of its tooth fossils (its teeth were more than seven inches long), paleontologists have been able to arrive at an estimate of the Megalodon shark as being from 79-82 feet long. During the Pliocene and Miocene Epochs, a large number of giant sharks roamed in the oceans. Megalodon would prey upon those and other turtles and fishes. It is known to have the highest bite force of any creature to have ever lived—as much as 1.8 tons of force per square inch.

It had a unique hunting style of biting off the fins of its prey before striking for the final kill. The shark was found all over the world when it lived around 23 million years ago. Their sheer size prevented them from venturing too far into shore. Although no one knows for sure why these sharks went extinct, it is believed that the Livyatan, a giant sperm whale and other killer whales, contributed to it. (1, 2)

7 The Haast’s eagle that went extinct over 500 years ago was the largest known eagle in the world and would prey on humans occasionally.

Today, eagles might appear harmless to most of us, but that was not always so. The Haast’s eagle is an extinct species of eagle that lived on the South Island of New Zealand, commonly called as the “pouakai” which was a monstrous bird of the Maori legend. The largest of this species could weigh as much as 230 kilograms and were larger than the vultures. They preyed upon large, flightless bird species and even those birds that weighed much more than them.

Their relationship with humans was not cordial. The Maori legends talk about the bird to be able to kill large prey, but they are also known to kill humans. The bird has featured in several documentaries including the one entitled Monsters We Met which was produced by the BBC. The closest living relatives of the bird are the little eagle and the booted eagle. (source)

8 “Entelodonts,” nicknamed “Hell Pigs” or “Terminator Pigas” were an extinct family of pig-like omnivores that lived during the Eocene Period. They were apex predators that hunted cow-sized animals and ate live animals.

Entelodonts were pig-like omnivores that lived in the forests about 21 million years ago. They had bulky bodies but short and slender legs with a weight of up to 400 kilograms. They had heavy, bony lumps on both the sides of their heads and had cloven hooves. They had a powerful set of teeth with large canines and heavy incisors making them an apex predator in Eurasia during the epochs of the Middle- and Early-Miocene.

They would consume live animals and plants but were biased towards the former. Featured in BCC’s and National Geographic’s programs, the Entelodonts were beasts with really strong jaw muscles that were not only dreadful but also unforgettable. (source)

9 “Dinofelis” was a medium-sized, saber-toothed cat that lived five million years ago. But don’t let its size fool you. The skulls of early humans have holes that align with the sharp upper canines of the Dinofelis, which mean that it was a man-eater.

Think of the entire cat family in the wild and you will think of lions and tigers. But have you ever heard that these cats have teeth so powerful that a hole could be made into your skull? The Dinofelis was a primate killer that shared a bad relationship with humans.

The study of the skulls of many early humans show holes that would have been made by the sharp, upper canines of this predator. This extinct, saber-toothed cat was widespread in Europe, Asia, Africa, and North America existing on the face of the Earth eight million years ago. (1, 2)

10 “Mosasaurus” was an extinct, deadly water lizard that could be as long as 56 feet and preyed on anything it could sink its teeth into. This terrifying carnivore had an extra set of teeth and weighed 5,000 kgs. The creature has been reimagined in the movie Jurrasic World.

That was not fiction. Longer than the T-Rex, the Mosasaurus had two extra sets of teeth, not exactly visible, inside its powerful jaw, but even then, swallowing its prey underwater was difficult for the creature. It did give birth in the sea but did not lay eggs. Like mammals, it gave birth to live babies.

The Mosasaurus’ fossils were found in almost every continent across the globe, including Antarctica. It preyed on fish, squid, and other small reptiles. These aquatic lizards lived during the Maastrichtian Age of the Cretaceous Period, around 70 million years ago. The first fractured skull of the creature was found in the Netherlands in 1764. (source)

So, Which prehistoric creature did you find the most terrifying?