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Since early last month, scientists at the Marshall Space Flight Center have been shooting X-rays through the skull of the Tyrannosaurus rex fossil known as Samson.
The result thus far has been more than 200 CT images showing the inner structure of the 65 million-year-old skull, one of the most complete and pristine T. rex skulls ever found.
"It hasn't told us too much yet," said Matt Lamanna, the Carnegie Museum of Natural History's dinosaur paleontologist. The real payoff is expected when the scanning is complete late next month.
Researchers will then take the 650 4-millimeter-thick vertical slices and meld them to produce a 3-D computer model of Samson's skull.
That visualization, in turn, could reveal much about Samson and about T. rex in general - the shape and size of its brain, the sharpness of the giant meat-eater's senses and hints about the function of air-filled spaces within its bones.
"To understand what's going on with these things, we really have to look inside," said Lawrence Witmer, an anatomy professor at Ohio University and an expert on the scanning and modeling of dinosaur bones.
Samson was found on a South Dakota ranch by a private fossil hunter in 1992 and was sold four years ago to Graham Ferguson Lacey, a British millionaire. Lacey last year hired the Carnegie to prepare the rock-encrusted skull for a planned European traveling exhibit and to study it.
Since May, the museum's preparators have been chipping away extraneous rock from the skull under the gaze of museum visitors. But in November the 1,500-pound specimen was crated up and shipped to Huntsville, Ala., so it could be examined using a large, industrial CT scanner at NASA's National Center for Advanced Manufacturing.
"CT scanning is becoming standard practice for dinosaur skulls of Samson's quality," Lamanna said. The X-rays reveal structures that simply can't be seen from the exterior, even after all the rock has been cleared away.
For instance, the endocranial cavity, or brain case, is a fairly accurate cast of the brain's exterior, but isn't ordinarily visible. The 3-D model built from the CT scans thus will tell scientists about the brain's size and shape. That, in turn, may provide hints about the animal's sensory capabilities.
An earlier such study of the brain case of Sue - another, more complete T. rex skeleton from South Dakota, now on display at the Field Museum in Chicago - showed that the brain had a sizable olfactory lobe, suggesting the creature "had a decent sense of smell," Lamanna said.
Similarly, Witmer said, an analysis of Samson's brain case may provide information about T. rex's senses of smell, hearing and sight.
Witmer has been involved in the scanning and modeling of numerous dinosaurs, including Sue. The 3-D visualization of Samson, he predicted, "will be in greater detail than was possible with Sue. The technology has advanced so much further."
Before CT scanning, paleontologists would have to study broken specimens to learn about these otherwise hidden structures. "There was a time when people would actually run these things through a bandsaw" to see inside, Witmer added.
In addition to the shape of the brain, the 3-D visualization will allow greater study of the large air sinuses found in the T. rex skull and perhaps provide more clues about their function.
The CT scanner at Marshall, built for examining rocket-motor assemblies and turbine blades, is about 10 times more powerful than a medical CT scanner, said Ron Beshears, who is heading the project at Marshall.
Beshears said the scanner was used to scan a portion of Sue's tail 10 years ago, as part of a feasibility study, but the Samson project is otherwise its first use for paleontology.
Samson will return to the Carnegie for additional preparation and study. The museum is to be finished with its work by May 2006.
(Distributed by Scripps Howard News Service, http://www.shns.com.)
Posted: Mar 02, 2005 9:49AM by Joe
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