We may laugh at the flightlessness of birds like ostriches and penguins nowadays but you did not want to mess with their oldest ancestor, Phosurhacida. Aka: The Terror Bird. It was the largest species of predators in South America between 62 million to 2 million years ago.
They were roughly 3 to 10 feet tall and munched on small mammals. They used their massive beaks to either pick up prey and slam them into the ground or inflict precision strikes on critical body parts. Archeologists say that this species left the world at about the same time we got here.