Scientists have discovered a 10ft tall bird-like dinosaur and dubbed it "the chicken from hell".
The long-legged creature lived alongside the Tyrannosaurus rex 66 million years ago.
Anzu wyliei weighed 500 pounds, measured 11.5ft from head to tail, and sported a cockscomb crest on top of its head.
It also had rudimentary feathers, sharp claws and a toothless beak. Experts believe it was an omnivore, eating both vegetation and small animals.
Dr Matt Lamanna, from the Carnegie Museum of Natural History in Pittsburgh, one of the US experts who described a newly constructed skeleton of the dinosaur, said: "We jokingly call this thing the 'chicken from hell,' and I think that's pretty appropriate."
The bones were found at sites in North and South Dakota in a rock formation known as Hell Creek that has been a rich source of dinosaur fossils, including those of the iconic T. rex and Triceratops.
Although the "new" dinosaur's remains were discovered years ago it took time for scientists to study and fully describe them.
Their findings appear in the online journal Public Library of Science ONE.
Co-author Dr Emma Schachner, from the University of Utah, said: "It was a giant raptor, but with a chicken-like head and presumably feathers.
"The animal stood about 10 feet tall, so it would be scary as well as absurd to encounter."
She added: "I am really excited about this discovery because Anzu is the largest oviraptorosaur found in North America.
"Oviraptorosaurs are a group of dinosaurs that are closely related to birds and often have strange... crests on their heads."
A variety of bones from three of the creatures were pieced together to make up almost a full skeleton.
Two of the specimens showed signs of injury, either as a result of accidents or violent encounters with other dinosaurs.
The Hell Creek formation consists of clay, mudstone and sandstone deposited on ancient flood plains where giant dinosaurs roamed towards the end of their reign, between 66 and 68 million years ago.