T. Rex Smelled Its Way Through Life

In Jurassic Park, the terrified kids held perfectly still so a hungry celluloid Tyrannosaurus rex couldn’t detect them.

In reality, scientists say, they would’ve been lunch meat.

CT-scanning of the desk-sized skull of Sue, the most complete T. rex fossil ever found, suggests the supreme carnivore in North America 65 million years ago had acute senses.

Its forward-pointing eyes provided a wide field of view, and ear structures suggest it could hear well.

Smell Was Key Sense

But Sue’s key advantage was smell. Its olfactory bulbs were grapefruit-sized. The skull opening for the bundle of olfactory nerves leading to the brain is wider than the spinal cord.

“The olfactory bulbs are larger than the cerebrum,” said paleontologist Chris Brochu of the Field Museum of Natural History, the only scientist to have extensively examined the Sue fossil.

The dinosaur “smelled its way through life,” he said.

Sue’s skeleton will be unveiled at the Field Museum on May 17 after nearly three years of cleaning and assembly. For now, it is off-limits to outsiders. Brochu has yet to reveal many details.

High Hopes for Sue

At a recent paleontology meeting, he said it was unlikely that the bones, however complete, would settle key debates about the superstar of dinosaurs.

Among them: T. rex’s color and vocalizations, whether it was warm-blooded, hunter or scavenger, male or female.

Others are more hopeful.

Thomas R. Holtz Jr. of the University of Maryland examined Sue briefly before it was auctioned in 1997, but key parts were still jacketed in protective plaster.

“The complete tail of a T. rex has not yet been described,” he said. “I would like to see if the furcula, or wishbone, is present.”

Peter Larson, president of the Black Hills Institute of Geological Research in Hill City, S.D., directed the fossil’s excavation in 1990. He spent two years examining the bones until they were seized by federal agents in a legal dispute.

Sue’s Last Meal

He believes the Sue fossil is an older female. Among predatory birds, fish and insects, females are larger than males, he notes. Sue has a wider pelvis that would accommodate egg-laying. And, similar to crocodile anatomy, she lacks an extra bone that male crocs and smaller, presumably male T. rex skeletons both have.

Reading behavior based on bones is trickier.

Sue’s teeth are foot-long cylinders with serrated edges. Her stomach contents included acid-etched bones of a duckbilled dinosaur. Other T. rex remains include bones from triceratops and other plentiful herbivores. A T. rex gulped everything and relied on a powerful digestive tract to process bone and horn.

In the movies, T. rex is a solitary killer. But many scientists believe the real-life carnivores hunted in packs.

Evidence? The Sue excavation also yielded juvenile and infant T. rexes in the same location.

Long before dying, Sue suffered a broken left leg that was slow to heal. “She couldn’t have hunted on it,” Larson said. “I think her mate helped her.”

How did Sue die? T. rexes fought each other, probably over territory, food and mates.

Fatal Battle?

Embedded in Sue’s ribcage is the tooth of another T. rex. The left side of the skull is smashed, with holes along her jaw.

Brochu doubts it is evidence of a fatal encounter. The holes don’t line up with the bite of a T. rex, he said.

Larson disagrees. “In her last fight she didn’t do so well,” he said.

T. rex might have ruled North America in the late Cretaceous Period. But on the roster of the biggest and baddest dinosaurs, some formidable predators are emerging around the world.

In March, scientists announced the discovery in Argentina of a yet-to-be-named meat eater that lived 100 million years ago. At 45 feet, it was 10 percent longer than T. rex. It had a long, narrow skull with scissor-like jaws, whereas the T. rex had nutcracker jaws.

“It probably attacked and dismembered its prey with a surgical precision,” said Phil Currie of the Royal Tyrrell Museum in Alberta, Canada. “T. rex was a creature of brute force.”

Other Meat-Eating Superstars

In 1998, researchers in central Africa found Suchomimus tenerensis. It was as large as a T. rex, but it prowled 30 million years earlier. Its pointy crocodile-like jaw sported 100 teeth. It also had 16-inch sickle claws.

In Argentina, Gigantosaurus was discovered in 1995. It weighed 50 percent more than T. rex and was a contemporary of Suchomimus about when Africa and South America were connected. It had thin, flat teeth like daggers.