Terror Birds are number 2 on The Most Extreme Awesome Ancestors. Their modern relatives are seriema birds. They were 150 kilograms and could run twice as fast as any human. They were armed with 10 centimeter long claws and a 60 centimeter long head that was practically all beak. With the extinction of the dinosaurs, the terror bird grew to become one of the top predators in South America.
- If following the countdown of extreme Awesome Ancestors, the final contender lived on the same plains of South America as the Terror Bird and towered over it, at more than 700 times the size of its modern descendent.