Aug 19, 2010 10:59 GMT  ·  By

Millions of years ago, strolling through South America meant more than just hacking our way through a rainforest, and avoiding the dangers that lurked within, it meant having to avoid terror birds.

These large creatures, averaging at around 7 feet (2.12 meters) in height, were terrestrial, having lost their ability to fly for many eons.

Their favorite pastime was roaming the land, killing their prey with their beaks, which they used similarly to how we use axes to chop wood.

While this may not seem terrifying at first, that's because you don't know that the terror bird's head is several times larger than that of a golden eagle, and roughly three times longer than a human skull.

It ends in an fiercely sharp beak, which the bird used to violently kill its prey, either by making it bleed to death, or by shattering its cranium.

Researchers generally agree that it would have been a bad idea for a hominin to have tried and capture the animal. The terror bird had no plans of being anyone's prey, and it would have most likely killed its hunter.

The feeding behavior of the flightless creatures was recently reconstructed, when investigators used computer tomography (CT) scans and computer models to get a better look at the giant bird.

Thus far, experts have discovered about 18 species of terror birds, all of which are long since extinct. The new research effort was only applied to one of these species, the team behind the work says.

“CT scanning extinct animals is exciting because you never really know what you’ll find inside. But you don’t need a CT scan to tell that this was one huge, bad-ass bird,” says Lawrence Witmer.

The expert holds an appointment as a paleontologist at the Ohio University, and is also a coauthor of a new study detailing the findings.

The paper appears in the August 18 issue of the renowned open-access scientific journal PLoS ONE August, a publication of the Public Library of Sciences, Wired reports.

The experts determined that creature lived more than six million years ago, when the South American continent was still isolated from the rest of the world.

The species which was analyzed in the new study was a smaller “version” of terror bird, weighing only 90 pounds (40 kilograms), and averaging a height of 4.5 feet (1.3 meters). The animal is called Andalgalornis steulleti.

“If the terror bird was coming down on its prey like an axe it would be very strong. Rather than slugging it out they probably attacked more like Mohammad Ali, with multiple attacks, jabbing then retreating repeatedly,” Witmer says.