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Kanab • The skulls of Utah's prehistoric lizards keep rolling out of the country's largest national monument with the two newest ones so unusual that when unveiled this week, their discovery will have a global impact.

That was the message during last week's lecture from paleontologist Scott Sampson, author, research curator for the Utah Museum of Natural History and host of the children's science program "Dinosaur Train" on PBS.

Although the names of the new species of horned dinosaurs will not be announced until Wednesday at the museum in Salt Lake City, Sampson said their significance lies in helping scientists determine that horned dinosaurs living at the same time in different areas of the continent evolved differently.

"It [the discovery] will have a huge impact," Sampson said last week at a public lecture at the Kanab visitor center of the Grand Staircase-Escalante National Monument.

His findings will be published Wednesday in PLoS, an online scientific journal.

One complete skull made from pieces of several skulls will be unveiled, along with a replica of the other.

Sampson said what is unusual about the latest skulls, both related to triceratops, is their enormous size along with their patterns and number of horns.

One skull is 7 feet long and probably was attached to a 20-foot-long body. Although the huge front horn near the tip of the snout points forward, the two smaller horns, also on the snout, point to the side instead of forward, as is common in other species. It also has a massive, bony, fanlike feature rising from the back of the skull.

The second skull also has a fan but is topped by 10 spiky bones, unique to the species. The 6-foot-long skull, probably on an 18-foot body, also has four sideways-pointing horns in addition to the main forward-pointing one on its snout.

"It has 15 horns on it," Sampson said. "It is the most ornate skull ever found."

The way the horns point sideways is far different from other triceratops living at the same time in other locales.

Sampson said they all lived on a "lost continent" during the late Cretaceous period about 75 million years ago, when North America had a smaller land mass divided north to south by a vast sea. The continent's western half is called Laramidia and the eastern half Appalachia.

A huge concentration of dinosaurs roamed Laramidia. The animals ranged from present-day Alberta to Mexico, including hot, humid and swampy southern Utah.

How such big populations survived remains a mystery, but the latest find seems to reject the theory that various species of the same groups, like horned dinosaurs, lived at different times. Sampson said the latest discovery seems to show different species in the same groupings existed at the same time.

Such huge populations may have been sustained by the ample vegetation for cold-blooded dinosaurs, which did not require as much food as warm-blooded animals.

Alan Titus, paleontologist for the Bureau of Land Management, which oversees the monument, said the scientific significance of the latest discoveries rates an 8 on a scale of 1 to 10. Titus and several other scientists contributed to the PLoS paper.

Titus said the finds essentially have proved horned dinosaurs were provincial 75 million years ago in western North America — with different species existing at the same time instead of at different periods.

"This is the first time we can show this beyond doubt," he said. "The same may be true for other families of dinosaurs [tyrannosaurs and hadrosaurs], but we cannot show it so conclusively yet. They also demonstrate the importance of Grand Staircase-Escalante National Monument in this whole scientific debate. It is no exaggeration to say it is one of the Rosetta stones of late-Cretaceous paleontology."

But what kept these huge populations of dinosaurs from mingling?

"That's the mystery." Titus said. "There doesn't appear to be any natural barrier."

Sampson, who was treated like a rock star by about two dozen children sitting on the floor during his lecture to about 100 people, said the find will bring added prestige to the monument in southern Utah's Kane and Garfield counties.

Since research began 11 years ago, he said, the monument has yielded fossils from 16 new species of dinosaurs.

Sampson said monumental discoveries in Utah and elsewhere have dramatically altered the view of dinosaurs. Instead of the creatures being stupid, dull, gray-colored, lumbering beasts, paleontologist now believe them to be spry, colorful, smart, adaptable and ancestors of modern birds. Scientists need to continue studying dinosaurs, he said, for what they can teach about a planet facing a sixth round of global extinction — accelerated this time from human impact on the land and seas. "Whether you think [global warming] is going on or not, it is," he said. "Studying dinosaurs can help us understand what it means."

Unveiling planned

P Skulls of two new horned dinosaur species will be unveiled to the public.

When • 4 to 8 p.m., Thursday

Where • Utah Museum of Natural History, 1390 E. Presidents Circle, University of Utah campus, Salt Lake City.

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