CHICAGO (WBBM NEWSRADIO) — As the Field Museum prepares to relocate its most famous resident, workers removed the skull of SUE the T-Rex Monday morning.

Contractors had to rock it back and forth a bit before dislodging its skull.

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SUE’s real skull, weighing 600 pounds, is still on display on the second floor of the museum. The head is separated from its body not because of weight concerns, as the sign for it says, but because “it is the most studied part of the skeleton.”

The disassembly of SUE, who made the Field Museum her home 18 years ago, is ahead of schedule, and likely to finish as early as the end of this week.

SUE’s encased skull sits upstairs for closer study; a replica has been used for the fossil skeleton. (Photo: Lisa Fielding/WBBM)

Bill Simpson, collections manager of fossil vertebrates at the museum, says when they reassemble the 67-million-year-old T-Rex, it’ll have a slightly different look.

“You don’t often get a second shot of mounting a dinosaur, but this time around, we are going to add in the so-called ‘belly ribs.'”

Simpson says they are able to do so because scientists have only recently learned how to position them.

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SUE is the largest, most complete and best-preserved Tyrannosaurus Rex fossil ever found, and was reconstructed with nearly 90 percent of her bones intact.

SUE also has a lively Twitter presence, even cracking jokes about the beheading.

The T-Rex’s more intimate suite is scheduled to be unveiled in 2019.

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You can stay involved on social media by following the hashtag “#SueOnTheMove.”