Terror Birds, scientifically known as Phorusrhacidae, were large, flightless birds that lived in South America from the late Paleocene to the Pleistocene epochs. They could reach heights of up to 10 feet and were characterized by their long legs, large beaks, and powerful bodies. These birds were apex predators, primarily feeding on small mammals and other birds. Despite their name, Terror Birds were not directly related to modern birds. They evolved separately and filled a similar ecological niche as raptors in other parts of the world. Their extinction is believed to be linked to climate changes and competition with emerging mammalian predators.