12 January 2025

Today we live among descendants of the dinosaurs, some of whom had relatives in common with the Terror Birds. Who were the Terror Birds? And who are their distant living relatives?

Terror Birds (Phorusrhacids) were a genus of large, flightless, carnivorous birds that thrived in South America from 43 million to 100,000 years ago. Wikipedia describes them as “among the largest apex predators in South America during the Cenozoic era.” 

As you can see from this diagram the largest of them could easily have eaten a human and, because Homo sapiens evolved around 300,000 years ago, we were on Earth before they went extinct. We would have been in danger but we were in Africa, separated by an ocean from these terrifying ancestors of modern birds.

DNA studies in 2024 refined the phylogenetic supertree of birds placing seriemas, parrots, falcons and songbirds in the clade Australaves, the group that evolved in South America and Australia. Click on the image below to see a larger version of the diagram.

Because the diagram has hundreds of tiny details I’ve hand-drawn the order Cariamiformes showing the Terror Birds family (Phorusrhacidae) and the last living branch, the clade Australaves: seriema, falcons, parrots and songbirds.

Australaves literally means “Southern birds” and includes those who evolved in South America and Australia. Interestingly, seriemas and falcons evolved in South America while the rest of the living tree evolved in Australia.

Let’s take a photographic journey through the living part of the tree.

The seriemas stand alone without other relatives. These South American birds have a lifestyle and appearance similar to the secretarybird of Africa, though they are not related. Here a red-legged seriema (Cariama cristata) kills a snake.

Then come falcons. Interestingly, everything else is a split from them.

Parrots evolved in Australia as a split from falcons. Further splits include …

… New Zealand wrens, who stand alone without other relatives …

… flycatchers …

… and all the other songbirds.

The birds we know today are far less dangerous than the Terror Birds.