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Livyatan melvillei -

Similar to a whale, this is another mysterious animal that inhabited the planet millions of years ago.

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Livyatan melvillei -

It lived approximately 13 million years ago, during the Miocene epoch. Fossils were discovered in 2008, in Peru.

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Mammoth -

The woolly mammoth went extinct 4,500 years ago. It inhabited cooler regions of the planet. Fossils have been found in Europe, northern Asia (specifically Siberia), and North America.

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Mammoth -

Mammoths lived up until the last Ice Age and served as food for humans living in the Neolithic period.

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Smilodon -

Also known as the saber-toothed tiger, this feline lived between 2.5 and 10 million years ago.

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Smilodon -

Similar to a leopard in appearance, this giant cat is believed to have emerged in North America and have gone extinct in South America.

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Megatherium -

This giant sloth lived during the Miocene and Pleistocene periods, between 10 million and 10,000 years ago.

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Megatherium -

The Megatherium was a herbivore that lived in what we consider North America. It reached the size of a modern African elephant.

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Canis Dirus -

Having lived during the Pleistocene epoch, the Dire wolf is believed to have gone extinct 10,000 years ago.

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Canis Dirus -

This big predator was about the same length as the modern gray wolf, but it weighed quite a bit more, at around 175 pounds (79 kg). They also had stronger bones than today's gray wolves.

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Purgatorius -

Similar to the rat, this prehistoric mammal lived approximately 65 million years ago in modern-day North America. It was an omnivore, and lived in trees.

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Doedicurus clavicaudatus -

This creature was a prehistoric glyptodon (an extinct subfamily of armadillos), which lived during the Pleistocene epoch and up until the last Ice Age, 11,000 years ago.

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Doedicurus clavicaudatus -

Looking like a mix between a tortoise and an armadillo, fossils were found in South America, more specifically in Argentina.

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Glyptodon -

Known as the ancestor to the armadillo, the aforementioned glyptodon was a mammal that lived in South America, from 3.2 million years ago to around 11,000 years ago. They were giants, reaching up to six feet (two meters) and weighing 880 pounds (400 kg).

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Gigantopithecus -

This giant ape lived on the planet between six million and 200,000 years ago. It lived in the current regions of China, India, and Vietnam.

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Gigantopithecus -

The species is known for its four partial jaws and nearly 2,000 large molars, canines, and other teeth. Now that's a lot of bite!

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Camelops -

The ancestor of the camel lived from the Pliocene epoch up until the end of the Pleistocene epoch, from 3.6 million years ago until 11,700 years ago.

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Camelops -

It had long and robust legs, a long neck, and one hump, making it similar to modern-day dromedaries. It lived in North and Central America, ranging from Alaska to Honduras.

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Paraceratherium -

Also called a rhinoceros-giraffe, this species is one of the largest terrestrial mammals that has ever existed.

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Paraceratherium -

It lived between 33 million years to 23 million years ago, across Eurasia, between China and the Balkans.

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Titanoboa cerrejonensis -

This snake lived on Earth millions of years ago, after the dinosaurs went extinct. It has been estimated that the giant snake measured up to 47 feet (14 m) in length.

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Phorusrhacidae -

Also known as terror birds, the Phorusrhacidae were large carnivorous flightless birds. They got as big as 10 feet (three meters) tall.

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Phorusrhacidae -

Among the largest predators in South America, they lived during the Cenozoic era, from 53 to one million years ago.

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Hipparion -

The ancestor of the horse lived around 20 million to two million years ago, on almost all continents.

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Entelodon -

Also known as the "pig from hell," this is probably due to its ferocious appearance. The entelodon had a large, bulky body, slender legs, and a long snout.

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Entelodon -

An ancestor of the pig, it lived in the plains of Eurasia until the end of the Eocene epoch, around 30 million years ago.

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Daeodon -

This giant animal, a subspecies of entelodon, had an appearance similar to a mixture of a dog, boar, and ox.

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Daeodon -

It inhabited North America around 23 to 20 million years ago, during the last Oligocene and earliest Miocene epoch.

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Procoptodon -

It inhabited North America around 23 to 20 million years ago, during the last Oligocene and earliest Miocene epoch.

See also: Extinct human species: how different were they from us?

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