巨型不飞鸟是“温和的食草动物”

 

A team of researchers from Washington, US, examined tracks uncovered in a landslide¹ in 2009.

 

Previous investigations² have suggested the giant bird was a carnivorous predator³ or scavenger⁴（食腐动物）.

 

But the absence of raptor-like claws in the footprints supports the theory that Diatryma was not a meat-eater.

 

Measuring 7ft (2.13m) tall and with a huge head and beak⁵, the giant flightless bird Diatryma (believed by some experts to belong to the genus Gastornis) is commonly portrayed⁶ as a fierce predator in both scientific works and popular media.

 

The animal is frequently thought as "the bird that replaced dinosaurs⁷ as the top predator", said geologist⁸ and team member George Mustoe, from Western Washington University in Bellingham, US.

 

"Let's be honest: scary, fierce meat-eaters attract a lot more attention than gentle herbivores."

 

The study, published in the journal Paleontology, analysed a set of footprints made 55.8 to 48.6 million years ago in the Lower Eocene. Preserved in sandstone, the prints formed part of the Chuckanut Formation in northwest Washington, US.

 

The team concluded that the multiple, well-preserved tracks were most likely to have been made by Diatryma.

 

That would make them the only known footprints left behind by this giant bird, and they provide new evidence about what it ate.

 

"[The tracks] clearly show that the animals did not have long talons⁹, but rather short toenails（脚趾甲）," said David Tucker, from Western Washington University, who also worked on the study.

 

"This argues against an animal that catches prey¹⁰ and uses claws to hold it down. Carnivorous birds all have sharp, long talons."

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