Terror Birds: Awesome Extinct Animals, Pt 4

Birds are typically not that scary (unless you’ve seen Hitchcock’s The Birds).  Most are smaller than humans and while many have sharp beaks and claws, they do not tend to target humans.  But I know the easiest way to make an animal’s name sound several hundred times scarier.  All you have to do is add a little bit of “terror”.

Today’s awesome extinct animal is the from the family Phorusrhacidae.  It is colloquially and pants-wettingly known as the Terror Bird.

Imagine Kevin from the beloved Pixar film Up.

Before source: Pixar Wiki
source: Pixar Wiki

Kevin stands about 3 times taller than Russel, the 8-year-old Wilderness Explorer.  If we assume Russell is only 3ft tall, this puts Kevin at about 9ft tall.  So she’s just the right height, but she is still kind of a pansy.  Let’s “terror” her up a little bit.

Let’s give her a wicked-sharp, 45cm long curved beak and some claws honed like meat hooks.  Now let’s beef up her legs so she can run 65 km/h.  Let’s give her some bulk (up to 150kg) and a taste for meat.  Now let’s set her loose on the grasslands of Pliocene North and South America.

After source: BBC Nature
source: BBC Nature

Nothing is going to willingly mess with these fellas.

First discovered in the late 19th century by one Florentino Ameghino, fossils from the Phorusrhacids are rare but have been found from Argentina to Florida.  They ranged in size from 3-10ft tall, but all were carnivorous and they tended to dominate their local ecosystems.  The sharp point on their beaks suggests that they used it for pecking with immense force, rather than grabbing and shaking.  These birds subscribed to the BOOM! HEADSHOT! way of life.

They appeared 62 million years ago in South America (shortly after the dinosaurs went extinct), and were striking fear into the hearts of small mammals for 60 million years before disappearing 2 million years ago.  An interesting problem has been arisen for researchers of these creatures because some of the North American fossils date to a time (5 Mya) before the Isthmus of Panama existed.  Since the birds could not fly, an intrepid group of Terror Birds must have either swam or hitched a ride on some sort of floating object.  This is still a topic of open investigation.

So why are we not always looking over our shoulders for impending doom in feathered form?

We don’t know.  I have been able to dig up only a 1994 Scientific American article that suggests competition from large cats and dogs may have been partially responsible.  The truth is there is very little evidence or discussion of the reason for their extinction.  I think it was a combination of grasslands turning to forests, prey adapting by burrowing or climbing, and competition from mammals.  Whatever the reason, the frightened primate part of me is kind of glad I don’t have to be on constant lookout for the tiny wings and huge beak of the Phoruscrhacids.

The natural scientist in me is disappointed these majestic creatures no longer roam the savannahs of the New World.

C'AWWWW! Source: Scientific American
Source: Scientific American




Blanco, R. E., & Jones, W. W. (2005). Terror birds on the run: a mechanical model to estimate its maximum running speed. Proceedings. Biological sciences / The Royal Society, 272(1574), 1769–73. doi:10.1098/rspb.2005.3133

Marshall, L. G. (1994). The Terror Birds of South America. Scientific American, (February), 90–95.



4 Replies to “Terror Birds: Awesome Extinct Animals, Pt 4”

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