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Top 10 Insanely Large Prehistoric Relatives of Modern-Day Animals

Ricky Rodson is an experienced cryptozoologist with several published books on the subjects of zoology, cryptozoology, and mythical beasts.

Whether it be plants and animals or amounts of food given to you at fast-food restaurants, things of the past almost always seem to have come in larger sizes. The last few million years have been scaling down the size of animals at a rate that seems almost systematic. And this is lucky for us because given the sheer size and power behind some of the animals on our list, I do not think we would have been able to survive had they not been. Some of the animals on our list will be a perfect demonstration to show much the world has changed in the millions of years it has existed.

Our list of insanely large prehistoric animals includes:

Megatherium

Glyptodon

Gigantopithecus

Terror Bird

Haast’s Eagle

Archelon

Short-Faced Bear

Deinosuchus

Titanoboa

Megaladon

When compared to the size of sloths today the Megatherium would feel like a real giant.

When compared to the size of sloths today the Megatherium would feel like a real giant.

10. Megatherium

The Megatherium was an enormous species of ground sloth that used to live in different areas of South America. Existing during the Early Pliocene period, this elephant-sized ground sloth is sometimes referred to as the giant ground sloth. In fact, is it so gigantic that there are few land mammals to have ever exceeded the size of the Megatherium. This beast of a sloth was originally discovered in Argentina back in 1788 but was not officially identified until the next year when it was looked over by the world-famous paleontologist Georges Cuvier.


Can you imagine if armadillos of today were still the size of their oldest relative the Volkswagon sized Glyptodon?

Can you imagine if armadillos of today were still the size of their oldest relative the Volkswagon sized Glyptodon?

9. Glyptodon

The massive Glyptodon was a type of large mammal that lived from 2.6 million years ago to only about 11,700 years ago. This heavily armored animal is said to be the oldest known relative of the modern-day armadillo. This living tank was about the size of small car with a smooth bony shell and turtle-like limbs. Despite its giant size, the Glyptodon was a peaceful creature that strayed away from danger whenever possible. Its grazing habits were usually found to be near water sources, feeding on mostly dicotyledonous trees and monocotyledonous grasses.

The Gigantopithecus is a massive Asian primate that many people believe inspired folklore like Bigfoot and the Yeti.

The Gigantopithecus is a massive Asian primate that many people believe inspired folklore like Bigfoot and the Yeti.

8. Gigantopithecus

The Gigantopithecus is believed to have lived amongst the dense bamboo forests of Asia. Its location, along with other forms of evidence based on modern-day primates has led scientists to think that this large ape was a herbivore. Fossil records prove that the Gigantopithecus is the largest of primates to have ever lived, standing to be nearly 9.8 feet tall and weighing almost as much as 1,320 pounds. Many people alive today claim that the Gigantopithecus is the scientific explanation behind such myths as the Tibetan Yeti or the American Bigfoot.


During its time on the planet, the Terror Bird was known to be a fierce apex predator.

During its time on the planet, the Terror Bird was known to be a fierce apex predator.

7. Terror Bird

The Terror Bird, also known scientifically as the Phorusrhacids, is an extremely large carnivorous bird that has been extinct for nearly 2 million years. At that time, these large beast were the apex predator of South America taking and eating whatever they wanted. The downwards curve of their beak suggested the bird evolved to rip meat from the bodies of animals. These massive birds were able to grow to sizes ranging in height from 3 feet to 9 feet tall. The closest modern-day relative to the Terror Bird is the Texas Seriemas which only stands a total of 31 inches tall. Boy how the times have changed.

The Haast’s Eagle existed all the way up until as little as 600 years ago.

The Haast’s Eagle existed all the way up until as little as 600 years ago.

6. Haast’s Eagle

The Haast's Eagle is a now-extinct species of eagle that was once believed to only be a Maori legend. It is the largest species of eagle to have ever existed and only lived on the South Island of New Zealand. The eagle is known to have grown to sizes larger than 9ft and weigh approximately 31 pounds. Its large size was believed to be an evolutionary response to the size of its prey. Haast's eagle went extinct around the 1400s when their primary source of food, the moa, were killed off by humans.

Once believed to be an ancestor of the leatherback turtle, the Archelon has recently to have been determined its own species.

Once believed to be an ancestor of the leatherback turtle, the Archelon has recently to have been determined its own species.

5. Archelon

Archelon is an extinct marine animal that roamed the waters during the Late Cretaceous. This giant turtle is the largest turtle known to ever exist, being over 15 ft long from head to tail and having a 13 ft flipper span. The Archelon also weighed nearly 5,000 lbs. This enormous turtle was once believed to be the oldest known ancestor of the leatherback sea turtle but now is known to be of completely different lineage. It is believed that as waterways began to migrate southward the Archelon was unable to adapt to the habits of new marine predators, this eventually led to their extinction.

When compared to modern-day bears, The Short-Faced bear was so large it can be hard to imagine.

When compared to modern-day bears, The Short-Faced bear was so large it can be hard to imagine.

4. Short-Faced Bear

The Arctodus Simus, or more lovingly referred to as the Short-Faced Bear, is one of the oldest known relatives to the modern-day Spectacled Bear. While the exact date it began to exist remains unknown, the Short-Faced Bear has been in North America for at least 800,000 years with it only going extinct about 12,000 years ago. And for the entire span of its existence, the Short-Face Bear was considered to be the biggest land-dwelling species of Carnivora that ever lived in North America. This massive bear shoulders stood at about 5 to 6 feet of the ground, this means that even while walking on all fours the Arctodus Simus would be tall enough to look an average-sized human in the eye.

The Deinoshuchus is a terrifyingly large crocodilian that lived during the Cretaceous period.

The Deinoshuchus is a terrifyingly large crocodilian that lived during the Cretaceous period.

3. Deinosuchus

The Deinosuchus is an extremely large but now extinct crocodilian that is related to the modern alligator. It thrived for nearly 9 million years and lived during the late Cretaceous period (approximately 82 to 73 million years ago). The average male Deinosuchus would range from 34 to 39 feet in total length and would weigh about 2.5 to 5 tons. Other than its very large size, the Deinosuchus generally looked the same as any other crocodilian alive today. But that is not to say that size is not a factor, because of its powerful jaws and large mouth the Deinosuchus would have been capable of taking down large dinosaurs given the opportunity. Despite this, the prehistoric alligator probably mainly focused on sea turtles and other aquatic animals for a large portion of its diet.

If you thought the snakes in the movie Anaconda were bad, wait until you see the Titanoboa.

If you thought the snakes in the movie Anaconda were bad, wait until you see the Titanoboa.

2. Titanoboa

The Titanoboa is the luckily extinct species of snake that was capable of growing to terrifying sizes. On average the snake was able to grow to sizes of to over 40 feet long and weigh over 2,400 pounds. Because only 28 fossils of this species of snake have been discovered, all of which date back around 58 to 60 million years ago, not much is known about this prehistoric snakes life. Scientists have discovered by examining the creature's jawline that despite its large mass, the Titanoboa was mainly piscivorous.

The Megaladon is one of the largest sharks to have ever existed, not much else differs them from the blood thirsty versions was have in our oceans today.

The Megaladon is one of the largest sharks to have ever existed, not much else differs them from the blood thirsty versions was have in our oceans today.

1. Megaladon

The Megaladon is an extinct species of shark that was capable of growing to immense sizes and take out even larger foes. Male Megalodons were known to grow upwards of 35 to 47 feet in length and weigh anywhere from 14 to 37 tons. The females were able to grow even larger with their general size being 44 to 56 feet long and weighing from 30 to 65 tons. Aside from the size difference, the Megaladon was said to both look and act similar to modern-day great white sharks found in the coastal waters of all oceans.

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.

© 2020 Ricky Rodson