Simplify the following text for a Grade 9 native English-speaking person.
Original: `` Sue '' is the nickname given to FMNH PR 2081 , which is the largest , most extensive and best preserved Tyrannosaurus rex specimen ever found .
Simplified: `` Sue '' is the nickname given to FMNH PR 2081 , the largest , most complete and best preserved Tyrannosaurus rex fossil ever found .