Terror bird is a group of extinct flightless birds thought to be fearsome predators. Predators are hunting animals. Terror birds lived about 60 million to 2 million years ago. There were about 20 species (kinds) of terror birds. Most species lived in South America.
Terror birds had massive heads with large, hooked beaks. Some species had skulls about 28 inches (70 centimeters) long, larger than those of any other bird. The beak alone could reach 18 inches (46 centimeters) long. Terror birds had strong necks and long, stout legs. Their short wings could not support flight, though the wings helped the birds maintain their balance while running. Some terror birds rank among the largest birds that have ever lived. They could reach up to 10 feet (3 meters) tall. Some weighed at least 500 pounds (230 kilograms). Other species were smaller, with some reaching only about 3 feet (0.9 meter) tall.
Terror birds lived in grassland and woodland habitats. Many were quick runners. Terror birds fed on a variety of rabbit-sized mammals and other animals. Some hunted larger animals. A terror bird could kill prey with blows from its heavy, pointed beak. It could also deliver strong kicks with its legs.
Scientists are not certain why terror birds became extinct. A land bridge began to connect North and South America about 3 million years ago. The bridge enabled animals to move more easily between the continents (see Great American interchange). One kind of terror bird spread to North America. But a number of predators crossed into South America for the first time. These predators included bears, cats, dogs, and other animals. Such predators may have competed with terror birds for food and space. Climate change also may have played a role in the extinction.
