World's Most Famous T. Rex Debuts in Chicago

By Rachel Louise Snyder

Though the palm-tree-dotted tropical sea way that was once America's west may have long ago evolved into the barren, desert that we know today, it was the landscape known to Sue, the giant Tyrannosaurus rex to be unveiled at Chicago's Field Museum on May 17.

Found in 1990 by self-taught field paleontologist Susan Hendrickson (for whom the dino is named), the 41-foot-long (12.5-meter) beast (13 feet, or 4 meters, tall at the hip) has spent the last decade undergoing the world's most exhaustive bath. Found with her nose inside her pelvis (a contortion baffling paleontologists), it took four people 21 days to excavate the 67-million-year-old Sue from 1,200 tons of dirt in South Dakota's Black Hills (near where the world's largest sea turtle was excavated). At 90 percent complete, Sue is the most comprehensive T. rex ever found (Stan, Sue's counterpart in Hill City, South Dakota, holds a close second). Sue offers one of only two T. rex arms ever found (though she has only one), and the most complete tail.

'IT'S TOO FAR-FETCHED'

How unusual is it to find a T. rex? (Think: Beatles unopened "The Butcher Cover." Think: Gutenberg Bible). Fewer than 25 have been found. You might find a portion of a triceratops or part of a duckbill dinosaur, but never a T. rex. "Every day we'd wake up [in the field]," Hendrickson says, "and jokingly say, 'Today I'm gonna get me a saber-toothed cat.' But a T. rex? You don't even joke about that. It's too far-fetched."

Sue's car-sized pelvis weighs a staggering 1,500 pounds (680 kg); her five-foot-two (1.5-meter) cranium is taller than most adolescents. Her 250 plus bones could fill a train car. A broken leg suggested evidence of a brutal fight initially thought to have caused Sue's death; now, however, some scientists believe her leg was merely arthritic.

"Bones [like Sue's] give you questions," says Terry Wentz, one of Sue's initial excavators and the chief preparator who worked on her skull before the Field Museum acquired her. "They don't always give you answers." Like, how did the other dinosaur bones found near Sue get there? Did dinosaurs travel in groups? Was Sue taken care of by other animals if she had a broken leg? How did she eat? And the biggest question of all: Is Sue male or female?

TRULY A DREAM FOSSIL

"Every once in a while you'd be working on Sue," recalls Wentz, "and you'd get this feeling it was looking at you and you'd realize you were working on an animal that was once alive... It's truly a dream fossil. It's the best of the best, the biggest, the most well-preserved. Everything you could ever want in digging a dinosaur was in Sue."

Now visitors to the Field Museum can watch a time-lapse video of the mounting of Sue's skeleton. They can touch casts of some of the bones in Sue found with wounds. And they can virtually traverse her cranium with animated CT images.

"She's just massive," says Hendrickson, who has waited nearly a decade for her monstrous namesake's unveiling and who laughs away the gender question as the domain of scientific debate. "I like it that the biggest, baddest carnivorous animal that ever lived was a female."

Taken from National Geographic Magazine, 2000