Terror Bird

Terror Birds were large predatory birds that lived during the Pliocene and Pleistocene Epochs. They were the apex predators of South America for millions of years before Smilodon came over the Isthmus of Panama.

Species
There were many different species of Terror Birds. Phorusracos lived in South America, while Kelenken, the largest of terror birds, lived in the southern United States.

Hunting
Terror Birds were carnivores. Their main prey in South America was probaly Macruchenia and other medium-sized mammals. It was most likely the same in the United States.

Social Behavior
Both Kelenken and Phorusracos had large brains in relation to their bodies. Much of their brain was taken up by an area that deals with social interaction. Their beaks were also hollow, and could make dozens of unique sounds. This would be crucial for pack cooperation. The bones of Terror Birds were often found together, suggesting this lifestyle even further.