The dinosaurs were a powerful animal group that ruled the Earth for over 140 million years, until a giant asteroid struck Earth 66 million years ago and wiped out all non-avian dinosaurs.

However, the avian dinosaurs, also known as birds, managed to persist and are represented by over 10,000 living species today. One group of avian dinosaurs, the terror birds, were carnivorous and lived mainly in South America for tens of millions of years. They possessed large hooked beaks, powerful necks, and razor-sharp talons, and some species grew to be some of the largest carnivorous birds to have ever lived.

The terror birds originated 53 million years ago with the smallest and slenderest member of their family, the Paleopterus. However, they quickly grew in size, with the arrival of the Paraphorusr, which stood at 1.4 meters tall and weighed around 180 kg. The terror birds were apex predators and used their clawed feet and sharp beaks to kill and dispatch prey.

Some paleontologists believe that they may have scavenged when the opportunity arose. The three most famous of the later giant terror birds were the Titanis, Kelen, and Brontornis, which spanned from the early Miocene to the early Pliocene.