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Tom Smart, Deseret Morning News
Scott Sampson holds an illustration of the "hagryphus giganteus" in Salt Lake Tuesday.

What's 7 feet tall, 13 feet long, armed with sickle-like claws and covered with feathers? Hagryphus giganteus, the new raptor dinosaur discovered in southern Utah.

The dinosaur was unveiled this week in a pair of press conferences held by the Utah Museum of Natural History, one on Monday in Escalante, near its discovery site, and the other on Tuesday in the museum on the University of Utah campus.

Fossilized remains of the animal were discovered in 2001 in Grand Staircase-Escalante National Monument and removed in 2002. Then they underwent careful preparation for several months, as workers chipped them from the rock matrix.

The name means "giant four-footed, bird-like god of the western desert," said Lindsay Zanno, a graduate student at the U. who named it and is the lead author of a paper describing the animal. The paper was published in the Journal of Vertebrate Paleontology.

Only about 7 percent of the fossil was recovered, said Scott Sampson, the museum's chief curator. That consisted of hand and feet bones, including the impression of the sharp keratin sheath that was curved like a huge cat's claw.

"We got the right 7 percent," said the field crew chief, Mike Getty, collections manager at the museum.

The remains were enough to allow reconstruction and show that this raptor was about twice as large as most other species of the variety. (An even larger one may have been the famous Utahraptor, which was 20 feet long.)

Sampson said Grand Staircase-Escalante National Monument is the "last great dinosaur boneyard in the lower 48 states." Other dramatic new species have been discovered there, he said, although this is the first to be formally named.

Under an agreement with the monument, which is administered by the Bureau of Land Management, the U. has been carrying out surveys and excavations in the region. The agreement was for five years, and that time is over. Now the U. is hoping for a positive response to a funding proposal submitted to the National Science Foundation.

In the past five years, U. and monument researchers spent nearly 17 months in field work in the rugged terrain. The workers included volunteers, some of which helped to haul out heavy specimens.

Other bones, jacketed in paper and plaster, were so heavy they had to be lifted out by helicopter. Those included the remains of a new duckbill dinosaur.

The birdlike giant discussed Tuesday dates to 75 million years ago, about as close to our time as it is to the Jurassic dinosaurs of 150 million years ago, Sampson said.

During the Mesozoic era, when the raptor roamed, the world had undergone global warming, Sampson said.

"It was a hothouse planet," he said.

North America was flooded, with a seaway stretching through the center of the continent from the Arctic to the Gulf of Mexico. In the western section, dinosaurs lived between the sea that reached to eastern Utah and a line of mountains.

That means the new finds come from "a really important place and time," Sampson said.

Strangely, dinosaurs from southern Utah at that time differ from those discovered in Montana and Canada. New finds have raised more questions than they have given answers.

The site is near the center of the 1.9-million-acre monument.

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"It can take you hours and hours to walk a mile" in the steep terrain, Sampson said.

Sometimes, he said, "if we're really lucky, we find a complete skeleton . . . and the preservation turns out to be impressive."

Sampson showed a photo of rock containing dinosaur skin impressions, which were notably knobby.

The skull of a yet-unnamed new duckbill dinosaur, which is on display at the museum, is 7 feet long.

Speaking of the raptor, Zanno said, "We know now that Hagryphus had feathers on its body."

Getty noted that a main reason the national monument was created "was to protect the paleontological resources."

E-mail: bau@desnews.com