Europe's Seven-Foot 'Terror Bird' Was Probably a Herbivore

About 55 to 40 million years ago, a massive "terror bird" roamed Europe. This creature towered at almost seven feet and had a beak that would make most run in fright. Now, though, scientists have made a surprising discovery; it turns out that this bird wasn't a predator and, instead, was most likely a herbivore.

The terror bird is also known as Gastornis. These large, flightless creatures were once thought to possess huge beaks that allowed them to grab and break the neck of their prey. They lived after the dinosaurs became extinct and when mammals were still at an early stage of their evolution. This means that the terror bird could have potentially been a top predator on land at the time.

Yet new evidence seems to indicate that these birds weren't ruthless carnivores. Palaeontologists discovered footprints that they believe belonged to the American cousin of the terror bird. Yet these footprints do not show the imprints of the sharp claws that might be expected of a raptor. In addition, the bird's sheer size and inability to move fast has made some researchers believe it couldn't have predated on early mammals.

In order to learn a little bit more about this large bird, the researchers analyzed the calcium isotope composition in fossilized bones of Gastornis. This allowed them to identify what proportion of the bird's diet was plant or animal. First, they tested their method on herbivorous and carnivorous dinosaurs as well as mammals living today. In the end, they found that the calcium isotope composition of terror bird bones are similar to those of herbivorous mammals and dinosaurs.

"Tooth enamel preserves original geochemical signatures much better than bone, but since Gastornis didn't have any teeth, we had to work with their bones to do our calcium isotope assay," said Thomas Tutken, one of the researchers, in a news release. "Because calcium is a major proportion of bone-around 40 percent by weight-its composition is unlikely to have been affected much by fossilization."

The findings reveal that far from being the ancient terror that researchers once thought, this bird was instead relatively benign. It fed mostly on vegetation and didn't hunt down its prey. It turns out the terror bird was, in fact, a gentle giant.

The findings were presented at the Goldschmidt conference on Aug. 29.