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Top 7 Fiercest Prehistoric Predators

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Read on to learn about 7 of the scariest prehistoric animals. These predators of the past could all likely take down an adult human with little to no effort.

Read on to learn about 7 of the scariest prehistoric animals. These predators of the past could all likely take down an adult human with little to no effort.

Deadliest Prehistoric Predators of All Time

Giant monsters once roamed the earth, and I'm not just talking about the dinosaurs: gargantuan arthropods, titanic snakes, and even oversized birds.

Humanity is the only species on the planet capable of interfering with the evolution and development of other lifeforms. Still, for hundreds of millions of years, we didn't exist, allowing prehistoric denizens plenty of time and space to grow.

Many of the smaller animals around today once existed in much larger forms, including predators like sharks, who are terrifying enough as it is.

Here are seven fearsome prehistoric predators, some of which could have swallowed a human in a single gulp.

Top 7 Scariest Prehistoric Animals

  1. Giant sea scorpion (pentecopterus decorahensis)
  2. Megaladon
  3. Giant boa constrictor (titanoboa)
  4. Tyrannosaurus Rex
  5. Mosasaurus
  6. Terror bird (phorusrhacidae)
  7. Spinosaurus

1. Giant Sea Scorpion

When? Paleozoic Era (541 to 252 million years ago)
Where? Fossils have been discovered all over, including Iowa
How big? Up to 2.5 metres long
Scientific name Pentecopterus decorahensis (named after an ancient Greek warship)

These ocean-dwelling arthropods are the earliest known large predator in the history of our planet. A fossil discovered in Iowa, which was once under an ocean, dates back to around 460 million years ago, long before dinosaurs roamed the earth.

Although they resembled scorpions in physical appearance, their tails didn't have stings. They probably used the multitude of claws protruding from their head to shovel prey into their mouth.

They are believed to be a distant ancestor to lobsters and crabs and land-dwelling arachnids like spiders and scorpions.

2. Megaladon

When? Early Mioceneera (23 to 15 million years ago) to the Pliocene era (5 to 3 million years ago)
Where? Megaladon teeth have been found on every continent except Antarctica
How big? 15 to 18 metres (three times longer than the largest record great white shark)
Scientific name Otodus megalodon (large tooth)

Giant fossilised teeth have been discovered all over the globe, belonging to a shark that was large enough to hunt whales (without help from other sharks).

Like the great whites of today, the megalodon was top of the food chain. Nothing could hope to stand against this terrifying monster of the deep.

It's believed to have gone extinct due to the cooling of the planet around 3.6 million years ago, resulting in a loss of habitat and the extinction or migration of many marine animals on which the megalodon preyed.

The ancient Maya used to leave fossilised megalodon teeth at their altars as offerings to the gods. The same teeth may have inspired Mayan legends of a sea monster named Sipek.

3. Giant Boa Constrictor

When? Middle to Late Paleocene era (60 to 58 million years ago)
Where? South America
How big? 12 to 14 metres long
Scientific name Titanoboa (titan + boa)

Around 30 fossils were discovered in the coal mines of Colombia in 2009; the remains of giant snakes that once inhabited the Cerrejón Formation.

Millions of years ago, a tropical rainforest grew where the open-pit coal mines now stand. Rivers crisscrossed the region, and the titanboa's size indicates that it would have spent most of the time in the water.

The rivers contained an abundance of prey for the snake, which was large enough to feed on crocodiles, giant turtles and lungfish.

4. Tyrannosaurus Rex

When? Late Cretaceous period (90 to 66 million years ago)
Where? North America and Asia (part of one continent at the time)
How big? 12 metres long, 4 metres high
Scientific name Tyrannosaurus Rex (tyrant lizard king)

This cretaceous carnivore needs no introduction, being the most famous of the prehistoric predators.

The T-Rex's deadliest weapon was its exceptionally powerful bite, which was strong enough to crush a car. It also had a sense of smell to rival that of bloodhounds.

There was a long-running debate about whether the T-Rex was a hunter or scavenger, but fossil evidence has since put that to rest. Unlike Godzilla, this iconic movie monster really existed.

5. Mosasaurus

When? Cretaceous period (90 to 66 million years ago)
Where? Atlantic ocean
How big? 14 metres long
Scientific name Mosasaurus (lizard of the Meuse River)

The gargantuan ocean-dwelling predator has become more prevalent in popular culture, to the point where it was featured in the 2015 movie blockbuster Jurassic World.

It went extinct millions of years before the megalodon appeared on the scene, so the two never had to compete for rulership of the ocean. One can't help but imagine what a clash of these titans would have looked like.

As it is, the mosasaurus, like the T-Rex, only had to worry about its own kind. The fossil of a mosasaur was discovered with a baby mosasaurus in its belly, indicating that the species was cannibalistic.

6. Terror Bird

When? 66 to 1.8 million years ago (during the Cenozoic era)
Where? South America
How big? 3 metres high
Scientific name Phorusrhacidae (terror bird)

When we think of predators that pose a threat to humans, birds generally don't come to mind. But the phorusrhacidae would be something to contend with if it was still around.

It was a flightless bird that could run extremely fast and stab things with its beak, like some kind of killer ostrich. It didn't have a strong bite, but its powerful neck would have compensated for this.

It's unclear what creatures they hunted. Researchers suspect they pursued smaller prey as their bite would surely not have been forceful enough to take down large animals. That said, the great white also has a weak bite, and that doesn't make it any less fearsome.

7. Spinosaurus

When? 100 to 93 million years ago (during the Cretaceous period)
Where? North Africa
How big? 12 to 18 metres long, 7 metres high
Scientific name Spinosaurus (spine lizard)

As more information has come to light, the spinosaurus has supplanted the T-Rex as the largest known land-dwelling carnivore to have ever existed.

That's not to say it could have beaten the tyrant king in a fight. The spinosaurus had a strong bite but nowhere near as powerful as the T-Rex's. It also had a poor sense of smell.

But the two existed in a different time and place, so we'll never know which one would have dominated the food chain.

The skull of the spinosaurus resembles that of a crocodile—long and narrow, with nostrils near the eyes. Like the crocodile, it inhabited both water and land; and may have hunted similarly too, lurking beneath the surface of the water and snatching unsuspecting prey from the shore.

The purpose of the spinal sail for which it is named is unclear. It may have been used to absorb heat, intimidate prey, or even impress potential mates—like peacock feathers during courtship.

Either way, as a relatively recent addition to popular consciousness, the spinosaurus makes for a fascinating specimen, even if it lacks the staying power of the T-Rex.


Russell Dean Christopher Bicknell, University of England; Patrick Mark Smith, Australian Museum. 2020, 3 July. Giant sea scorpions were the underwater titans of prehistoric Australia (

Associated Press in Washington. 2015, 1 September. Five foot seven and claws out of its head: meet Earth's first big predator (

Josh Davis. Megalodon: the truth about the largest shark that ever lived (

General information.

Patrick Pester. 2021, 20 April. Mosasaurus: Apex ocean predator of the dinosaur age (

Joseph Castro. 2017, 17 October. Tyrannosaurus Rex: King of the Dinosaurs (

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.