12 million years ago, a fearsome predator roamed the ancient landscapes of South America. It was a giant, flightless bird popularly known as a “terror bird.” And now, paleontologists have uncovered a new clue about this terrifying creature.
A team of researchers analyzed a 12-million-year-old fossilized bone discovered in Colombia’s fossiliferous Tatacoa Desert some 20 years ago.
Interestingly, this fossilized leg bone likely belongs to one of the largest terror birds ever found.
The remains of this extinct giant carnivorous bird offer new insights into ancient South American ecosystems.
“Terror birds lived on the ground, had limbs adapted for running, and mostly ate other animals,” said Siobhán Cooke, associate professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.
Examination single-bone fossil
The Miocene age bone extends the known northern range of this bird species in South America.
Although the bird’s leg bone fossil was discovered nearly two decades ago, it wasn’t recognized as belonging to a terror bird until 2023.
In early 2024, researchers created a 3D digital model of the specimen to facilitate further analysis. This led to the identification of more details about this meat-eating bird.
Terror birds were apex predators, standing up to 3 feet to 9 feet tall. They were powerful hunters, capable of taking down large prey with their massive beaks and sharp claws.
This particular fossil terror bird was likely around 5 to 20% larger than other known species.
The fossil only comprises the distal portion of a left tibiotarsus, a lower leg bone in birds analogous to the human tibia or shin bone. It belongs to a Phorusrhacid, an extinct bird.
Surprisingly, the bone also bears cuts believed to be bite marks from an extinct crocodile species called Purussaurus. This massive crocodile, estimated to be up to 30 feet long, was a formidable predator in its time.
The presence of these tooth marks suggests a violent encounter between the Phorusrhacid and the Purussaurus.
“We suspect that the terror bird would have died as a result of its injuries given the size of crocodilians 12 million years ago,” added Cook.
Rivers flowed in the region once
The majority of terror bird fossils have been discovered in the southern regions of South America, including Argentina and Uruguay.
The discovery of a Phorusrhacid fossil in Colombia — the northernmost find of its kind — indicates that these giant predatory birds were more widespread than previously thought.
This fossil provides crucial insights into the ancient ecosystem of the region, which was once a lush riverine environment. The terror bird coexisted with a diverse range of animals, including primates, hoofed mammals, giant sloths, and armadillo-like glyptodonts.
The modern-day seriema bird is believed to be a distant relative of these ancient predators.
“It’s a different kind of ecosystem than we see today or in other parts of the world during a period before South and North America were connected,” Cooke noted.
The specimen, likely the first of its kind from the site, suggests the species was relatively rare 12 million years ago.
“It’s possible there are fossils in existing collections that haven’t been recognized yet as terror birds because the bones are less diagnostic than the lower leg bone we found,” the author concluded in the press release.
The findings were published in the journal Palaeontology.
