Researchers have found a 66-million-year old dinosaur called Anzu wyliei. The dinosaur referred to as "chicken from hell" by its discoverers was as tall as a human and had sharp claws.

The team described the dinosaur as a giant flightless bird with a rounded crest and long, slender legs. It weighed around 440-660 pounds.

The fossil was found by scientists at Carnegie and Smithsonian Museums and the University of Utah.

"We jokingly call this thing the 'Chicken from Hell,' and I think that's pretty appropriate. So we named it after Anzu, a bird-like demon in ancient mythology," said Matthew Lamanna, a paleontologist at the Carnegie Museum of Natural History in Pittsburgh, according to a news release.

Anzu was a theropod dinosaur, which were monstrous bipedal dinosaurs and some of the largest hunters that roamed the earth.

The three fossil skeletons of Anzu were found in North and South Dakota. The site where researchers discovered the bones is called Hell Creek Formation and is known to contain fossil remains of several dinosaurs.

The creature was probably the largest member of the Oviraptorosaurs or "egg-thief" dinosaurs. These dinosaurs were closely related to birds, AFP reported. The latest discovery, researchers hope, will shed light on the mysterious group of dinosaurs called Caenagnathidae to which Anzu belongs.

According to Schachner, Anzu is "one of the youngest oviraptorosaurs known, meaning it lived very close to the dinosaur extinction event." The event called K-T extinction [Cretaceous-Tertiary (K-T)] occurred when an asteroid hit earth around 65 million years ago.

The current study also supports the recent claims that Gigantoraptor- the largest known oviraptorosaur- was also a caenagnathid, NBC news reported. Gigantoraptor weighed 1.5 tons.

"Anzu is far and away the most complete caenagnathid that has ever been discovered. After nearly a century of searching, we paleontologists finally have the fossils to show what these creatures looked like from virtually head to toe. And in almost every way, they're even weirder than we imagined," Lamanna said in a news release.

Anzu shared its territory with Tyrannosaurus rex and triceratops. Researchers found that two of the three specimens had injuries; one had a broken toe while the other had a healed rib.

The study is published in the journal PLOS ONE.        

A cast of Anzu wyliei can be seen in Carnegie Museum of Natural History's Dinosaurs in Their Time exhibition.