Tuesday, May 30, 2006

Largest of the tank dinosaurs

New dinosaur find is big - in more ways than one
By Greg Lavine

From The Salt Lake Tribune

As Utah researchers continue to pluck out bits of a potentially new armored dinosaur species, the find may become known for more than its massive girth.

The plant-eating creature, which would have tipped the scales at an estimated 6 tons, could help answer questions about an important period of change during the Cretaceous era. College of Eastern Utah scientists are in their second field season of scouring the badlands south of Green River for bones. "This region of the world is a key place to understanding dinosaur transitions," said Jeff Bartlett, director of research at CEU's Prehistoric Museum in Price.

About 125 million years ago, the 30-foot-long armored beast stomped around a lush, subtropical Utah in search of the leafy stuff. At some point, a flooding event may have buried the lone giant along with a horde of smaller dinosaurs. CEU field workers are now reaping that ancient harvest, which may be yielding the heaviest known armored dinosaur.

"We're finding a spectacular trove of bones," Bartlett said. Most of the 300-plus bones unearthed are from therizinosaurs, the group that includes Falcarius utahensis, a missing link species discovered on a nearby plateau. Falcarius is thought to mark a transition in one dinosaur family's move from a meat-centered lifestyle to a plant-based diet.

While the large, unnamed armored dinosaur was found alone, smaller relatives named Gastonia burgei have been discovered in Utah in small groups. This raises questions about whether the hefty beast roamed alone or if any companions escaped fossilization, said Reese Barrick, director of the Prehistoric Museum.

Barrick said Gastonia and the new find, though likely related, may have behaved differently. Because larger creatures often need more territory to roam in order to stay well-fed, this could have prompted the potential new species to keep to itself, he suggested. The new find was twice the size of Gastonia burgei and three times as heavy.

Bartlett said it is unclear whether the two relatives roamed at the same time, or if they lived in different parts of the Cretaceous era. Further investigation at the site, located on Bureau of Land Management property, could answer this question and more. Other issues up for debate are how climate changes and vegetation shifts affected the overall populations of dinosaurs in various regions, as flowering plants began to appear during the Cretaceous.

It may take a few more field seasons to gather enough information to definitively decide whether this is a new species. So far, vertebrae, ribs and pieces of armor plating have been found. Prepared bones from the new find will be on public display in the Price museum within the next year.

A mounted skeleton would be at least five years away, and that assumes the museum could find a spot for the bulky skeleton, Barrick said. Much of the reason for speculating this is a new species comes down to size differences, as adult bones from the new find are significantly larger than those of Gastonia burgei.

Celina and Marina Suarez, who were then Temple University graduate students, discovered the site in 2004. State paleontologist Jim Kirkland turned the site over to CEU as his group is busy with the Falcarius quarry and another nearby dig site, which may contain all new species from the earliest part of the Cretaceous if the dates are proven correct.

"There's a lot going on down there," said Scott Foss, the BLM's regional paleontologist, adding that Brigham Young University as well as some out-of-state teams have permits to work the rugged terrain of southern Utah.

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