Terror Birds: Predators With a Kung Fu Kick?

John Pickrell
for National Geographic News
August 1, 2005

Phorusrhacids would give even Alfred Hitchcock the shivers: Also known as terror birds, some were nearly 10 feet (3 meters) tall, weighed over half a ton (500 kilograms), and could swallow a dog in a single gulp.

A new study suggests the extinct predators may have been as fleet-footed as modern cheetahs and that some species may have kicked the bones of their prey kung-fu-style to obtain marrow.

The study is one of the first to shed light on the hunting behavior of these huge, flightless predators, which dominated South America from about 65 million to 2.5 million years ago.

Dog Swallower

"Imagine an ostrich with larger, more powerful legs and neck, armed with massive claws," said Herculano Alvarenga, a terror-bird expert at the Museu de História Natural in Sao Paolo, Brazil.

"An ostrich, the largest living bird, can swallow an apple. But a phorusrhacid could swallow a medium-sized dog in one gulp," Alvarenga said.

The smallest known terror bird, Psilopterus lemoinei, was the size of a harpy eagle and weighed about 18 pounds (8 kilograms). The largest terror bird was the gargantuan Brontornis burmeisteri, which stood nearly 10 feet (3 meters) tall and weighed a whopping 1,100 pounds (500 kilograms).

During much of the time that terror birds walked the Earth, South America was an island continent adrift, and its unique cargo of species evolved in isolation from the rest of the world.

But three million years ago South and North America collided. The event is thought by some experts to have allowed North American predators, such as jaguars and saber-toothed cats, to outcompete remaining terror-bird species to extinction.

Relatively little is known about the way terror birds lived their lives. There are no large, flightless carnivorous birds alive today for scientists to observe and extrapolate from, and few complete terror-bird fossils have been unearthed.

Researchers still do not know if terror birds hunted in groups—as velociraptors (bipedal dinosaurs who share a similar body shape) are thought to have—or alone, as jaguars or tigers do today.

Experts believe the extinct birds were meat-eaters because their beaks resemble those of predatory eagles and scavenging vultures.

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