It's called the chicken from hell: a birdlike dinosaur some 2.1 metres tall that weighed around 226 kilograms when it roamed western North America on its long, slender hind legs.

The beast got its nickname long ago at the Carnegie Museum of Natural History in Pittsburgh, where a replica of its skeleton has been on display for a decade.

But the species has had no scientific name. Until now.

The creature was formally introduced to the scientific community Wednesday as scientists published a description and analysis of its anatomy, and finally bestowed a name: Anzu wyliei. The moniker comes from a mythological feathered demon plus the name of a Carnegie museum trustee's grandson.

Anzu had a toothless beak and a crest on its skull like a rooster's comb, combined with long arms and sharp claws up to about 10 centimetres long. It apparently also had feathers over much of its body.

The analysis, in the journal PLoS One, concludes that Anzu belongs to a group of dinosaurs that scientists knew little about, because they had recovered only fragmentary remains from its members. In contrast, the three specimens of Anzu from North and South Dakota that were included in the analysis collectively supply a nearly complete skeleton, said Matthew Lamanna of the Carnegie museum.

Anzu "reveals the anatomy of these creatures almost from head to toe," said Lamanna, lead author of the new paper.

The dinosaur lived some 66 million to 68 million years ago in a hot and humid landscape, rather like the Louisiana bayou, he said. It ate plants and maybe small animals when it wasn't fleeing from a hungry and much bigger T. rex, he said.

When it came to naming the creature, why not go with a spiffed-up version of "chicken from hell?"

That was actually the first choice, Lamanna said. But it turns out the phrase isn't nearly as catchy in Latin or Greek.

"All the names we came up with were just ridiculously unpronounceable," he said.

So "I thought that if I couldn't come up with a name that literally meant `chicken from hell,' I could at least name it `feathered demon'"