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Dinosaurs' Inner Ears Differed, Researchers Say

Posted on: Thursday, 9 March 2006, 18:00 CST

By A.J. HOSTETLER

Anatomist Lawrence Witmer of Ohio University used CT scans to compare Tyrannosaurus rex's brain structure (top) to that of the more lumbering Diplodocus. ST. LOUIS P aleontologists are using new technologies from medicine and biotech to "flesh out" what they know about T. rex and other dinosaurs.

What they're finding could shed light on the evolution of dinosaurs to their descendants, modern-day birds and crocodiles, and how evolution works, said Jack Horner, the Museum of the Rockies expert of "Jurassic Park" fame.

He joined a panel of scientists yesterday describing their current research at the annual meeting of the American Association for the Advancement of Science.

"We can't observe dinosaurs," Horner said, so scientists are turning to CT scanning to learn more about dinosaur brain structure, for example, or to cellular and microbiology to reveal bone components, including protein and someday perhaps even DNA.

Paleontologists can use the giant Tyrannosaurus rex to provide a look backward in dinosaur history as well as a way to look forward to modern animals.

Anatomist Lawrence Witmer of Ohio University described his new research using CT scans to compare T. rex's brain structure to that of the more lumbering Diplodocus. He focused on what the brain cavity could uncover about the inner ear, the organ responsible for hearing as well as balance, and the nostrils and olfactory region of the brain.

Both dinosaurs apparently had large olfactory brain regions, indicating that smell was an important sense. But their inner ears, which provide clues about head posture, alertness and agility, greatly differed, Witmer said.

T. rex has the inner ear of a much smaller, agile animal, while Diplodocus has a stubby inner ear, suited for a slow, ponderous animal, he found. This gave the gigantic T. rex a heightened sense of hearing and balance, suggesting an alert head posture with the ability to rapidly turn its head and eyes to track prey.

"What we're seeing now is . . . predatory prowess was maybe even greater than we thought," Witmer said. "We can start to flesh out these dinosaurs" with this information, he added.

Mary Higby Schweitzer of North Carolina State University looks at dinosaurs at the molecular level.

Using electron microscopy and other techniques that demineralize fossilized bone, she has found that despite the passage of tens of millions of years, bones from more than 15 specimens still contain soft tissue, blood vessels and red blood cells and bone cells. These constituents can differ with the animal's age and sex.

"It's very, very surprising," she said.

Her latest work, which will be published this spring, suggests that certain chemicals such as hemoglobin may help preserve the soft constituents. The work also could improve our understanding of how the same molecules in humans change as we age, she said.

Michigan State University biogeochemist Peggy Ostrom also is focusing on molecules, particularly proteins, the building blocks of bone. She uses mass spectrometry to analyze what molecules are in a bone sample.

"Molecules are fossils, too," she said.

Proteins could be key to understanding dinosaurs, she said, because it appears some proteins can endure longer than DNA. The proteins can tell us about diseases, about where prehistoric animals fit in the food chain, what they ate and who they are related to.

Contact staff writer A.J. Hostetler at ahostetler@timesdispatch.com

or (804) 649-6355.

ILLUSTRATION: DRAWING

Source: Richmond Times - Dispatch

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