Popularly known as ‘terror birds,’ phorusrhacids are an extinct clade, or branch, of giant flightless, meat-eating birds that were the dominant predators in South American for tens of millions of years. These enormous birds, which stood up to 10 feet (3 meters) tall and had large hooked beaks, became extinct about 2.5 million years ago.
Now, in a discovery that shows terror birds were a far more diverse group than previously thought, paleontologists have unearthed an unusually complete and well-preserved fossil of a new species called Llallawavis scagliai, or ’Scaglia’s Magnificent Bird.’ The find is detailed in the current issue of the Journal of Vertebrate Paleontology.
The new specimen is exquisitely preserved, with more than 90 percent of the skeleton intact, a statement by the Society of Vertebrate Paleontology (SVP) said. But scientists are particularly excited by certain anatomical details that are almost never found in the fossil record. The auditory region of the skull, voice box, complete trachea, bones for focusing the eye, and the complete palate are revealed in this fossil, the statement said, giving researchers a unique opportunity to understand how these extinct feathered carnivores sensed the world. 
For example, this terror bird, which stood about four feet (1.2 meters) tall, appears to have had below-average hearing, suggesting that “Llallawavis may have had a narrow, low vocalization frequency range, presumably used for intraspecific communications or prey detection,” explained lead author Dr. Federico ‘Dino’ Degrange of the Centro de Investigaciones en Ciencias de la Tierra and the Universidad Nacional de Cordóba in Argentina, in the SVP statement.
“The discovery of this species reveals that terror birds were more diverse in the Pliocene than previously thought,” added Degrange. “It will allow us to review the hypothesis about the decline and extinction of this fascinating group of birds.”
