The reign of the terror birds

Andalgalornis steulleti, a flightless predatory bird from the late Miocene, early Pliocene of Argentina.

E00FPW Andalgalornis steulleti, a flightless predatory bird from the late Miocene, early Pliocene of Argentina.

Source: BBC

By Niki Wilson

What has feathers, T-rex-like feet, and a hooked beak that could sever the spinal cord of a horse with one blow? It might sound like a beast from a fantasy novel or horror film, but in fact it’s a creature that actually existed – the scariest bird you can imagine, scaled up to nightmarish proportions. Say hello to the terror bird.

After a meteor wiped out Velociraptor and Tyrannosaurus rex, the terror bird family rose to occupy the niche of terrifying top predator in South America – a supremacy that lasted for almost 60 million years. During that time, 17 species in this family of lethal-beaked meatheads came and went, all the while gorging on a smorgasbord of plant-eating mammals until these scary birds disappeared about 2.5 million years ago.

With few fossils documenting their existence, the behaviour of these birds is still somewhat of a mystery. What exactly did these feathered aggressors get up to, and why did they disappear? It’s a story that paleontologists have been painstakingly unearthing for over 100 years. What they’ve learned so far suggests the birds were absolutely dominant as predators, voraciously gobbling up prey across the continent.

The second coming

Sixty million years ago the continents had largely assumed the geographic position they occupy now, though what we now know as Central America had not yet been created. South America was an island, and while saber-toothed cats and wolves took over the job of top predators elsewhere, most mammals in South America were happy herbivores. This buffet of lumbering vegetarians provided the fresh flesh that terror birds feasted on.

A head reconstruction of Andalgalornis steulleti (Credit: Stocktrek Images, Inc/Alamy)

A head reconstruction of Andalgalornis steulleti (Credit: Stocktrek Images, Inc/Alamy)

All birds are considered dinosaurs – most being closely related to meat-eating dinosaurs such as the velociraptor that disappeared 65 million years ago. In a way, the reign of the dinosaur never truly ended in South America, it merely changed form.

Its beak was designed to make powerful up and down movements

Dr Luis Chiappe, Director of theDinosaur Institute at the Los Angelos Museum of Natural History, agrees. “Nature continues to fill the gaps as animals evolve, and the world evolves,” he says. “It’s fascinating to think of the terror birds as the dinosaurs of the Cenozoic era in South America.” On that continent, he says, there were no animals that could rival these birds at the top of the food chain.

So how did they do it? What exactly made these terror birds so terrifying?

Death by terror bird

Terror comes in many forms, something one learns quickly when trying to understand how terror birds, hunted, killed and eviscerated their prey. It’s really not the kind of research to be done before bedtime – there are apparently several options available to an animal equipped with a pickax for a beak.

It’s generally agreed that terror birds were seriously carnivorous, but there’s long been debate over how they killed prey, says Dr Stephen Wroe, Director of the Function, Evolution & Anatomy Research (FEAR) Lab at the University of New England, Australia. Based on CT scans of fossils from the terror bird known as Andalgalornisan agile, swift-moving bird that lived between 23 and 5 million years ago – Wroe and colleagues were able to narrow down the type of movements this animal was capable of.

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