August 19, 2010

Ancient Bird Fought With Its Beak

According to a new study, 90-pound birds that once lived in South America used their giant, sharp beaks like a boxer giving their opponent a quick jab.

Researchers reported in the online journal PLoS ONE that the creatures, officially known as Andalgalornis, were built to strike forward, attacking their prey with sudden jabs.

"These guys were not sluggers, they couldn't go in and grapple with prey. They had to stand back and dance around and make hatchet-like jabs," Lawrence Witmer of the Ohio University College of Osteopathic Medicine told The Associated Press.

The design of the birds' head "dictated what their killing style must have been. Attack and retreat strategy ... trying to kill the animal then swallow it whole, if they could, or use the bill and strong neck muscles to rip off chunks of flesh," he said in a telephone interview with AP.

The birds stood at 4 1/2-foot tall and roamed the earth about 6 million years ago in northwestern Argentina.  The Andalgalornis had a skull that was deep, along with a bill that was narrow and armed with a powerful hook.

"Birds generally have skulls with lots of mobility between the bones, which allows them to have light but strong skulls. But we found that Andalgalornis had turned these mobile joints into rigid beams. This guy had a strong skull, particularly in the fore-aft direction, despite having a curiously hollow beak," Witmer told AP.

An engineering analysis found that the bird was well equipped to strike with its beak and pull back, but it would have been badly strained if it tried to shake prey from side-to-side.

Hard sideways shaking could damage the bird's hollow beak.

According to research led by Witmer and Federico J. Degrange of Museo de La Plata in Argentina, using the beak like an ax could compensate for the bird's weak bite.

Witmer told AP that the researchers were surprised by the findings.

The thought process going in to the research was "these were pretty tough guys, and they absolutely were, but they had to be kind of careful," he said. "Being a predator is a really risky business. A prey animal is going to fight back."

He said the researchers approached the study both anatomically and by using engineering to simulate potential behaviors of the creature.

"The cool thing was we both came up with the same answer," he told AP. "And a surprising thing is we could figure it out ... and feel pretty good about it."

The creature was one of a variety of giant birds that lived in South America during that time.

The U.S. National Science Foundation funded the research along with the Australian Research Council, the Australia and Pacific Science Foundation and the National Fund for Scientific and Technological Investigation of Argentina.


Image Caption: The terror bird Andalgalornis by John Conway


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