We all know what birds are. They're warm-blooded creatures that have feathers, can fly, sing, and are pretty friendly (unless you happen to be a rodent facing a bird of prey). There were times when fierce birds roamed the Earth. Throughout the Cenozoic era (the time period after the dinosaurs up to now), the world has seen ferocious predators known as Terror Birds.
Terror Birds is a term given to a large, flightless, predatory bird. They can be as tall as a person, or even taller. What separates these birds from other giant flightless birds like the ostrich is their beaks. They were thick and powerful, perfect for bringing prey down. If they were still alive, pets would most likely be on the menu (maybe even people).
One of the earliest terror birds was Gastornis (known in North America as Diatryma). Gastornis stood about as tall as a person (sometimes even taller by six inches), had a beak built like an upside down canoe, and was top predator of its time. It lived during the late Paleocene and the Eocene eras in what is now North America and Europe. During this time, mammals were still small and had not yet risen to power. This was the time when birds were in charge. Gastornis was capable of eating what it wanted, mainly small mammals like Propaleotherium and Eohippus (which would later evolve into horses). However, as time went by, mammalian predators would evolve, and probably were able to out-do the Gastornis. Inability to adapt is probably what caused Gastornis to pass on into extinction.
Years later, during the late Pliocene era, another Terror bird would appear in what would become South America. This Terror Bird, known scientifically as Phorusrhacos, stood about eight feet tall and had legs built for running. It also had the honor of being the first to receive the nickname Terror Bird since its discovery in 1887, but wouldn't be recognized as a bird until four years later. Phorusrhacos probably hunted small mammals like Gastornis, but these probably were limited to offspring. I think there are two possibilities for why it went extinct:
1) It got out-competed by Smilodon (better known as the Saber-Tooth Tiger).
2) It couldn't adapt to the Ice Ages.
Whatever the reason, these birds would've made family outings to South America a bad idea.
There are many more terror birds in the fossil record, but those two are easily the best known thanks to the documentary Walking with Beasts. These two have become some of my favorite Terror Birds, but if any others catch my interest, I'll be sure to blog about them. In the meantime, here's a little tribute to Terror Birds in popular media:
I will say this: I don't think the Earth has seen the last of the Terror Birds. In my opinion, if we wait long enough, the secretary bird of Africa might evolve into the world's newest Terror Bird. But like I said, it's only a guess. We may never know if such predators will walk on the planet again.