Simplify the following text for a Grade 8 native English-speaking person.
Original: Jonathan Jacob Walker ( born September 17 , 1985 in Chicago , Illinois ) is an American rock musician and former bassist of Panic !
Simplified: Jonathan Jacob Walker ( b. September 17 , 1985 in Chicago ) is the bassist for the Las Vegas based rock band Panic at the Disco , replacing former bass player Brent Wilson .