Two newly discovered horned dinosaur species from an ancient "lost continent" are some of the most surprising and ornate yet found, paleontologists say.
The new dinosaurs are members of the ceratopsids, the group of dinosaurs that includes Triceratops. The animals were generally four-legged herbivores with horns and bony frills rising from the backs of their heads.
The larger of the two dinosaurs, Utahceratops gettyi, had a 7-foot-long (2.3-meter-long) skull, prompting study co-author Mark Loewen of the University of Utah to compare the animal to "a giant rhino with a ridiculously supersized head."
The other new dinosaur, Kosmoceratops richardsoni, is "one of the most amazing animals known, with a huge skull decorated with an assortment of bony bells and whistles," study leader Scott Sampson, also of the University of Utah, said in a statement.
Kosmoceratops' head is covered in horns: one on the nose, one over each eye, one at the tip of each cheek, and several running along the dinosaur's head frill. (See pictures of other "extreme" dinosaurs.)
"Most of these bizarre features would have made lousy weapons to fend off predators," Sampson said. Instead, the horns were likely a sexual display to attract mates or intimidate rivals.
New Utah Dinosaurs "Icing on the Cake"
Several partial fossils of both Utahceratops and Kosmoceratops were unearthed in Utah's Grand Staircase-Escalante National Monument, home of what was once the "lost continent" of Laramidia.
During the Cretaceous, the central region of North America flooded, separating the eastern and western portions of the continent for about 30 million years. The western side effectively became its own distinct landmass. (See a prehistoric time line.)
"If you were a time traveler and you went back to the late Cretaceous, you could take a boat from the Gulf of Mexico and sail all the way up to the Arctic Ocean and you wouldn't see land," Thomas Holtz, a vertebrate paleontologist at the University of Maryland, told National Geographic News.
The region that was once Laramidia is now a hot bed of fossil discoveries, in part because of geological activity going on at the time, said Holtz, who was not affiliated with the present study.
"The Rocky Mountains were actively forming. We had mountains being pushed up and torn apart. ... Sediment [was] washing downhill and providing what would eventually be sedimentary rock that could entomb all these fossils."
In general, Utahceratops and Kosmoceratops are only the two most recent in a series of horned dinosaur discoveries from around the world, and the study authors believe that more new horned fossils will soon be unearthed.
"The new Utah creatures," said study co-author Andrew Farke of the Raymond M. Alf Museum of Paleontology, "are the icing on the cake."
The new-dinosaur paper was published online this week in the journal PLoS One.