Fossil gives 'voice' to the terror bird

Brett Smith for redOrbit.com – @ParkstBrett

Sixty million years ago, a group of large predatory flightless “terror birds” stalked the South American continent in search of prey.

In a new study published by the Journal of Vertebrate Paleontology, paleontologists have described a new species of terror bird, dubbed Llallawavis scagliai, based on some of the most complete fossil remains ever recovered for one of these creatures.

The study team noted that their remains included the skull’s auditory region, voice box, trachea eye bones and palate, which allowed for the first-ever exam of the sensory abilities of these terrifying birds.

The study team added that the find may help explain the behavior, ecology and evolution of the birds.

“The mean hearing estimated for this terror bird was below the average for living birds,” said study author Dino Degrange, from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) in Argentina. “This seems to indicate that Llallawavis may have had a narrow, low vocalization frequency range, presumably used for intraspecific acoustic communication or prey detection.”

Generally speaking, Terror birds were up to 10 feet tall with hooked beaks. These birds were the apex predators of the area during the Cenozoic Age in South America. By comparison, Llallawavis was about 4 feet tall and lived in Argentina around 3.5 million years ago towards the end of terror birds’ run.

“The discovery of this new species provides new insights for studying the anatomy and phylogeny of phorusrhacids and a better understanding of this group’s diversification,” said co-author Claudia Tambussi, also from CONICET.

“The discovery of this species reveals that terror birds were more diverse in the Pliocene than previously thought,” Degrange said. “It will allow us to review the hypothesis about the decline and extinction of this fascinating group of birds.”

While terror birds have been described as vicious carnivores, one particular bird known as Gastornis may have in fact been a plant eater, according to a 2013 study.

Footprints of the bird did not show evidence of sharp claws expected of a carnivorous raptor and the 2013 study used an isotope assay to show that the calcium in the bones of Gastornis is consistent with that of herbivorous mammals and dinosaurs.

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