One of the giant reptiles, dubbed the Utahceratops gettyi, had a 7-foot-long head. The other, called Kosmoceratops richardsoni, the most-ornate dinosaur ever unearthed, had 15 horns: 1 over the nose, 1 over each eye and at the tip of each cheekbone, and 10 across the back of its bony frill. Each dinosaur was about as heavy as a hippopotamus.
The dinosaurs are cousins of the Triceratops and are the southern neighbors of the Chasmosaurus, said Scott Sampson, the lead author of a paper on the beasts that will appear in the journal PLoS One. They lived on an island continent, dubbed Laramidia, when what is now North America was divided by an interior sea that ran along the eastern side of the Rockies, extending from the Gulf of Mexico through Alaska. The climate was swampy and subtropical.
“This points to the fact that the world of dinosaurs was more unusual than we’d previously thought,” Sampson, a paleontologist at the Utah Museum of Natural History and the University of Utah, both in Salt Lake City, said in a telephone interview. “How do you jam so many giant dinosaurs on such a small chunk of land?”
The team of paleontologists found bones and skulls of the new dinosaurs at Grand Staircase-Escalante National Monument, and there are probably many more discoveries waiting there, Mark Loewen, a paleontologist at the Utah museum who is another author of the paper, said in an interview. The site only opened 10 years ago, and 2 to 3 new dinosaurs are found there every year, he said.
The site remained unexplored for so long because it’s difficult to reach, and getting the dinosaurs out requires a helicopter because of the rough terrain, Sampson said.
Utahceratops, initially discovered by the museum’s Mike Getty in 2000, was about 6 feet high at the shoulder, and 18 to 22 feet long. It weighed about 3 to 4 metric tons (6,600 to 8,800 pounds).
Kosmoceratops, first found in 2007 by volunteer Scott Richardson, was smaller, about 15 feet long. It weighed about 2.5 metric tons.
Skulls of the dinosaurs will be on display at the Utah Museum of Natural History for the rest of the year.
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