CHICAGO — Scientists at Chicago’s Field Museum have removed the right forelimb of the institution’s famous T. rex fossil named Sue.

Sue’s bones are headed to the suburban Argonne National Laboratory to be part of research into the long-debated question of why T. rex had a forelimb, the Chicago Tribune ( ) reported.

“It’s been one of the enduring mysteries in dinosaur paleontology,” museum collections manager Bill Simpson said.

The goal is to find signs of stress in the bones’ cellular structure that would show to what degree the T. rex used the limbs.

Beginning Saturday, Carmen Soriano, the laboratory’s paleontologist, will put Sue’s radius and ulna, the two main forelimb bones, before a scanner that’s typically used to look at barely visible things. Soriano said the X-ray will generate a 3-D image of the arm bones, both inside and out, down to the cellular level.

Sue’s bones will return to the museum Tuesday.

The dinosaur’s bones show many signs of injury it suffered during its 28-year-old life, the newspaper reported, and it’s not the first time they have been taken off for a study. According to Simpson, the most recent study was done by a University of Chicago graduate student, who borrowed Sue’s shoulder bone to study the signs of muscle attachment. And a few years ago National Geographic also borrowed a forelimb.

The sex of the dinosaur is unknown, but it was named Sue, after Sue Hendrickson, who discovered the skeleton on a South Dakota ranch in 1990.

Sue has been on display in the Chicago Field Museum since 2000.

Information from: Chicago Tribune,