Discover the Largest Bear to Ever Exist (Up to 4X The Size of a Grizzly!)

Written by Colby Maxwell
Updated: January 31, 2023
© Daniel Eskridge/Shutterstock.com
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Key Points

  • A. angustidens is estimated to have weighed between 900 and 2,645 lbs and stood between 11 and 14 feet tall.
  • A. angustidens likely died out before then, probably around 700,000 years ago.
  • At their largest, Kodiak bears can grow to 1,500 lbs and stand over 10 feet on their hind legs.

Bears are among the foremost predators on earth today. Although the planet is currently home to some massive bears, prehistoric bears used to be much, much, bigger. Polar bears and grizzlies may be one thing, but the largest bear to ever live dwarfed them.

Today, we will discover the largest bear to ever exist and learn what happened to this massive beast. Let’s get started!

Arctotherium angustidens, the largest bear to ever live

Discover the Largest Bear to Ever Exist (Up to 4X The Size of a Grizzly!)
The Arctotherium, seen here in a sketch drawing, was found largely in South America.

© Robert Bruce Horsfall (1869–1948) / public domain – License

Arctotherium angustidens was an ancient species of bear that belonged to the Arctotherium genus. Although all members from this genus are extinct, this group of bears were the largest to have ever lived. Of this group of megafauna, one bear was the largest; Arctotherium angustidens.

This bear was the earliest and largest member of the entire genus and by far the largest bear to have ever lived.

Size

A. angustidens is estimated to have weighed between 900 and 2,645 lbs and stood between 11 and 14 feet tall. Besides being the largest bear in history, its sheer size would have put it in contention for the largest carnivorous land mammal to have ever lived.

One particularly large individual was discovered in Buenos Aires and had an unusually large humerus bone. Using this new fossil as an estimate, some scientists argue that A. angustidens could have weighed between 2,167 and 4,502 lb, although our previous figures are a bit more conservative.

Distribution

A. angustidens fossils were first discovered in South America. The ancient ancestors of the species likely crossed the Isthmus of Panama during a period of time known as the Great American Interchange.

Within the continent of South America, these bears seem to have stayed within a region known as the Southern Cone. The Southern Cone encompasses the southern countries south of the Tropic of Capricorn.

The highest concentrations of A. angustidens were likely found in Argentina, especially in the Buenos Aires Province.

When Did the Arctotherium angustidens Live?

Discover the Largest Bear to Ever Exist (Up to 4X The Size of a Grizzly!)
A. angustidens went extinct around 700,000 years ago.

©Daniel Eskridge/Shutterstock.com

A. angustidens belonged to a temporal range between the Pleistocene and Holocene. The first members of the Arctotherium genus likely lived around 2 million years ago before dying out 10,000 years ago, spanning a period of nearly 1.99 million years. A. angustidens likely died out before then, probably around 700,000 years ago.

This migration and eventual evolution of A. angustidens was likely encouraged by the extinction of the metatherian sparassodont carnivores (marsupial-like mammals) in South America. With little competition, the migrating carnivores would have thrived as they expanded into the region.

Although A. angustidens was likely the first member of the Arctotherium genus, other members evolved soon after. Other members of the genus include A. vetustum, A. bonariense, A. tarijense, and A. wingei.

What is the largest bear currently alive?

Discover the Largest Bear to Ever Exist (Up to 4X The Size of a Grizzly!)
The polar bear is the largest living species of bear.

©Vaclav Sebek/Shutterstock.com

Although it’s a pretty close competition, polar bears are usually recognized as the largest bears in the world. Males (larger than females) usually weigh up to 990 lbs and can stand up to 10 feet tall. The largest polar bear ever recorded was a male killed in Alaska in 1960. This individual weighed 2,209 lbs and stood 11 feet 1 inch tall on its hind legs.

Grizzly bears, specifically Kodiak grizzly bears, are a close second. These grizzlies live in the Kodiak Archipelago in southwest Alaska. At their largest, Kodiak bears can grow to 1,500 lbs and stand over 10 feet on their hind legs.

The closest modern relative of Arctotherium angustidens

Discover the Largest Bear to Ever Exist (Up to 4X The Size of a Grizzly!)
The spectacled bear is the closest living relative of Arctotherium angustidens, who lived in South America during the Pleistocene period.

©Andrei Preda/Shutterstock.com

Although no members from the Arctotherium genus are still around, there are closely related species still alive today. The South American spectacled bear is a relative of the genus and belongs to the Tremarctinae subfamily, just like Arctotherium.

Spectacled bears are also known as Andean bears, Andean short-faced bears, or mountain bears, and they live along the Andean Mountain range in South America. These bears generally weigh 220-440 lbs and stand 6-7 feet tall when on their hind legs.

Why did Arctotherium angustidens go extinct?

The last member of the Arctotherium genus likely lived until around 10,000 years ago. The genus likely went extinct as the large prey they hunted became extinct while competition increased from other predators, notably humans.

Next Up…


The Featured Image

A saber-toothed cat tries to drive a short-faced bear out of its territory.
Arctodus bears' teeth were two inches long and their claws were 3 inches long, so they probably didn't have to fear saber-toothed cats.
© Daniel Eskridge/Shutterstock.com

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About the Author

Colby is a freelance writer from Charlotte, North Carolina. When he isn't distracted by his backyard birdfeeder, you can find him camping, exploring, and telling everyone around him about what he's recently learned. There's a whole world to learn about and Colby is content to spend his life learning as much as he can about it!

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