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A scientist compares the humerus of a newfound giant bear with the humerus of an elephant.

Paleontologist Leopoldo Soibelzon holds an upper arm bone of the giant bear next to an elephant's.

Photograph courtesy Leopoldo Soibelzon

A comparison of the bear and a human.

South American giant short-faced bear vs. typical human. Diagram courtesy Blaine Schubert.

Christine Dell'Amore

National Geographic News

Published February 3, 2011

There's a new titleholder for the biggest, baddest bear ever found.

A prehistoric South American giant short-faced bear tipped the scales at up to 3,500 pounds (1,600 kilograms) and towered at least 11 feet (3.4 meters) standing up, according to a new study.

The previous heavyweight was a North American giant short-faced bear—a related extinct species—that weighed up to 2,500 pounds (1,134 kilograms). The largest bear on record in modern times was a 2,200-pound (998-kilogram) polar bear shot in Alaska in the 19th century.

The South American giant short-faced bear roamed its namesake continent about 500,000 to 2 million years ago and would have been the largest and most powerful meat-eater on land at the time, scientists say.

(Related: "Ancient Bear DNA Mapped—A First for Extinct Species.")

As meat-eaters go, "there's nothing else that even comes close" during the time period, said study co-author Blaine Schubert, a paleontologist at East Tennessee State University in Johnson City, Tennessee.

"It just blew my mind how big it was."

The bear skeleton, found in Buenos Aires Province, Argentina, in 1935, was recently reexamined by Schubert and study co-author Leopoldo Soibelzon, a paleontologist from Argentina who specializes in South American fossil bears.

By measuring its almost elephant-size humerus, or upper arm bone, the team was able to calculate the size of the rest of the bear's body, Schubert said.

Their analysis also revealed that the animal was an old male that had endured several serious injuries throughout his life.

For Bear, Size Matters

Less certain, however, is what and how these bears ate—and why they were so different from their North American cousins, Schubert noted.

For instance, the South American giant short-faced bear species started huge and became smaller over time, while the North American species grew bigger.

In South America, Schubert suspects, a glut in prey and a lack of competition combined to make the bear king of the continent. But as more meat-eaters evolved, short-faced bears adapted, becoming smaller and more omnivorous, like the modern-day black bear.

(See "Comet 'Shower' Killed Ice Age Mammals?")

In North America, the short-faced bear's increasing size may have offered an advantage—its sheer heft may have scared off saber-toothed cats and other predators from their kills, the researchers speculate.

And the short-faced bear's reign in North America would have also coincided with an explosion in Ice Age megafauna, such as giant ground sloths, camels, and mammoths—all potential new food sources.

"We had an Africa here," Schubert said, and "it's gone now."

The biggest-bear study appeared in the January issue of the Journal of Paleontology.

1 comments
Jacq Khal
Jacq Khal

A size of an elephant. A bear. @____@ That's just scary!

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