Terror birds- 10 feet tall, carnivorous and in armies- ruled Southern America, millions of years ago, the National Geographic reported. CT scans of the inner structures of the bird's ear indicated that it could only hear sounds toned in a low - pitch, and most likely made ostrich-like sounds.
With the recent discovery of Llallawavis scagliai, a new terror bird species, paleontologists are obtaining new sets of information about this predator, the Society of Vertebrate Paleontogy published.
At least 90 percent of its fossilized skeleton was uncovered in 2010 in the Northeastern part of Argentina, making the unearthed the most comprehensive terror bird sample ever discovered.
Dr. Lawrence Witmer, a paleontologist from the University of Ohio and not part of the research team, said "It's rare to find such a complete fossil of anything, let alone a bird. This is a very exciting find."
Llallawavis family, with the help of the samples, was discovered to have lived around 3 million years earlier, towards the end of the reign of the terror birds. Unlike the other gigantic members of the family, it only measured four feet in height and 40 pounds in weight.
Dr. Federico Degrange, the lead researcher from Argentina, said "The discovery of this species reveals that terror birds were more diverse in the Pliocene than previously thought. It will allow us to review the hypothesis about the decline and extinction of this fascinating group of birds."
The researchers have verified that low-key sounds are excellent for long-distance communication, especially for predators that are on the lookout for prey animals' movements.