Video: Terror bird

Lethal weapon (Image: Ridgely & Witmer, Courtesy of WitmerLab at Ohio)

Animals in South America around 6 million years ago would have been well advised to steer clear of the Andalgalornis steulleti “terror bird”. The flightless bird brought down its prey by stabbing it with its enormous hooked beak.

Andalgalornis, which lived in the area that is now Argentina, belonged to a group of enormous flightless birds known as terror birds that appeared around 60 million years ago and stuck around for at least 58 million years. It was 1.4 metres tall – small compared with other terror birds, which could reach 3 metres – and resembled a cross between an ostrich and a hawk.

Now, a team at Ohio University in Athens has revealed how the bird would have used this beak to fell prey. For this, they used CT scans to create a 3D model of a fossilised Andalgalornis skull, then used a technique borrowed from structural engineering to simulate the effects of different forces on the skull.


This revealed that Andalgalornis must have killed with a violent jabbing motion worthy of a sword-wielding gladiator.

Beastly beak

The team found that unlike most birds, Andalgalornis had a well-buttressed and inflexible skull. Vigorous front-to-back pecking would not have harmed it, but the skull could not have withstood side-to-side forces.

“It could not hold prey in its beak and shake it from side to side like a dog,” says team member Lawrence Witmer.

Witmer suggests that the bird would nimbly step in and deliver targeted blows with its beak. “These animals also had wickedly nasty feet and talons,” says Casey Holliday of the University of Missouri in Columbia. The birds could have used these to hold prey animals down and rip into them with their beaks.

Journal reference: PLoS One, DOI: 10.1371/journal.pone.0011856