Sixty million years ago, just after the dinosaurs died out, giant birds with weaponous beaks—and heads that vaguely resemble a T. Rex—ruled over what is now South America.

The discovery of a new fossil of the aptly-named “terror bird” provides the most complete look at the feathered predator to date. The new find suggests these birds had the ability to inflict some serious pain on their prey. The fossil also offers new insight into the formidable creature’s vocalizations: The preserved middle ear suggests that they were great at hearing low frequencies, and therefore probably communicated with a low bellowing sound.  Exactly why these birds—faster and more fearsome than any of their modern relatives—went extinct 2.5 million years ago remains a mystery.

Here’s how modern birds stack up against their long-dead relative.

Size:

Mode of transport:

  • Terror birds: Couldn’t fly, but they were plenty menacing on the ground.
  • Modern birds: Ostriches don’t fly either. Instead, they use their wings to balance while running. Seriemas can fly, but prefer to keep their feet planted firmly on the ground and use their wings primarily to woo mates.

Speed:

Vocals:

  • Terror birds: From the fossil’s intact inner ear, the part that sits just past the eardrum, researchers learned that the terror birds heard low frequencies—around 2,800 Hz—and therefor posit that they probably had deep vocals to match.
  • Modern birds: Ostriches and emus make low-frequency noises, possibly similar to those of the terror bird. So, here’s what the ancient beast might have sounded like, compared to most other birds, which sing at 1-4 kHz.

Diet:

  • Terror birds: Terror birds ate anything smaller than them. And the most recent fossil includes a newly discovered bone that strengthened the connection between the skull and the beak. Its presence confirms that the birds were strong enough to use their faces as a “hatchet” against other animals.
  • Modern birds: Seriemas have a carnivorous streak, too: In addition to plants, they eat lizards, frogs, rats, and other birds. They can’t hack their food, but they do pick it up and slam it against the ground.

Predation:

  • Terror birds: They were the top predators on the continent of South America, before it collided with North America and jaguars and sabertooths entered the competition.
  • Modern birds: Cassowaries, Australian birds that are slightly smaller than ostriches and are closely related to the terror bird, have quite the mean streak. In 2013, Outside magazine suggests death-by-Cassowary as one of the top 10 worst ways to go. After a 30 MPH chase, this is how it could play out:

“The bird kicks and you stumble across a log. In a flash, it leaps nearly five feet into the air, landing beside your neck. You cover your face in fear as the cassowary nears. With one powerful kick, it opens a half-inch gash, nicking your carotid artery. Hearing your screams, a nearby camper comes to your aid, shooing off the bird. Within seconds of his arrival and eight minutes after the gash was formed, you slip into unconsciousness.

Yikes. Now imagine that scenario with a faster chase and a larger beak hacking at you. That’s what death by the most fearsome bird in the history of the world would be like. 

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