Terror Birds: The Last Dinosaurs

The Terror birds, known scientifically as “Phorusrhacidae,” are an extinct family of predatory birds that inhabited South America from the late Eocene (50 million years ago) to the late Pleistocene (1.5 million years a). In a way, they were the last remaining vestige of the dinosaurs – large and fast predatory birds with huge heads, powerful legs, strong beaks, and streamlined bodies which were built to take on prey of all sizes. They hunted across the South American landmass for millions of years with little to no competition from any of the continent's smaller mammalian predators.

The largest of the species were Titanus walleri and Kelenken, which could reach heights of up to 9.8 feet (3 meters) tall and a body weight of up to 220 lbs (100 kg)

All species of Phorusrhacids were predator, and no matter their size or niche, they used their massive heads as pickaxes to deliver deadly blows to their prey. They had huge, powerful feet with four large talons, well-equipped for chasing down food and stomping out rivals, as well as tremendous, beak-tipped beaks that allowed them to tear flesh from carcasses and fight off any would-be challengers. 2.7 million years ago, the great American biotic interchange – “the collision between North and South America” – occurred, in which the two landmasses merged to become one giant supercontinent. This allowed for new species migrations to occur and diversification to take over.

Creatures from the North American continent, like smilodon, big cats, wolves, bears, camels, deer, and mastodons, all made their way south to a new ecosystem in which they were highly successful. While the majority of South America's unique and formerly isolated mammalian species were quickly outcompeted by the new arrivals. Giant ground sloths, glyptodons, opossums, and terror birds were some of the few species that were able to migrate north and find niches for themselves in this new habitat. However, for the terror birds, it would be short-lived. While they did have an initial impact and adapted relatively well to their new home in the southwestern portion of the United States, chasing down early horses, fighting off saber-tooth cats, and expanding from southern California to Texas, they were no match long-term for the new competition they had to face off with.

Even though they were large, vicious, agile, and intimidating, they were too specialized at hunting certain prey and not able to compete with the success of the other, more generalized predators of the time, which included canids, big cats, and bears.

Displaced and outcompeted by these new mammalian predators who were smarter and more adaptable, the Terror birds eventually vanished into extinction between 1.8 and 1.2 million years ago.