Dinosaur-hunting paleontologists are reporting the find of the fossilized remains of a new giant raptor, described as the largest such example ever found possessing wing feathers.

Dubbed Dakotaraptor — for its discovery in South Dakota's fossil-rich Hell Creek Formation — it would have been around 17 feet long, making it one of the largest feathered raptors identified to date, researchers say.

"This new predatory dinosaur also fills the body size gap between smaller theropods and large tyrannosaurs that lived at this time," says University of Kansas paleontologist and study co-author David Burnham.

In size, Dakotaraptor would have been in between the smaller Velociraptor, about the size of a turkey, and a close but much older cousin known as Utahraptor that was thought to be around 22 feet long, researchers said.

The fossil of Dakotaraptor has been dated to around 66 million years ago, they said.

Despite its size, it would have been a quick-moving creature, says research leader Robert DePalma of the Palm Beach Museum of Natural History.

"This Cretaceous period raptor would have been lightly built and probably just as agile as the vicious, smaller theropods, such as the Velociraptor," says DePalma, who is the museum's curator of vertebrate paleontology.

Dakotaraptor carried a 9.5-inch curved claw on the middle toe of its hind legs, the fossil shows.

The fossilized forearms of Dakotaraptor steini showed evidence of the presence of "quill knobs" where feathers would have been attached, he says, "our first clear evidence for feather quills on a large dromaeosaurid (raptor) forearm."

While most likely too large to fly, the feathers could have been used for mating displays or to keep eggs warm in a dinosaur nest, researchers suggest.

Dakotaraptor demonstrates that flightless but feathered dinosaurs probably evolved several times in the lineage that eventually led to modern birds, experts say.

"Either it evolved from an ancestor that could fly but had lost the ability to fly, like an ostrich, or dinosaurs evolved big quill-pen feathers for another reason, such as display or egg brooding," suggests Steve Brusatte, a dinosaur researcher at the University of Edinburgh who was not involved in the published study.

The Dakotaraptor study and description has been published in the journal Paleontological Contributions.