Credit: Dean/Bryan/

Thursday in the park with Bronx...and Meagan!

On Thursday, Pete Wentz hit an L.A. park with Bronx, his 2-year-old son with ex Ashlee Simpson. Joining the dad and son was a pretty, mysterious brunette.

A source confirms that the Fallout Boy rocker, 32, is dating the young woman, a model named Meagan Camper.

Back in February, Simpson, 26, filed for divorce after three years of marriage, citing irreconcilable differences.

The actress and singer (and younger sister to Jessica) has already stepped out post-split with two guys: Rocker Craig Owens (who is signed to Wentz's record label), whom she briefly dated in the spring; and Boardwalk Empire actor Vincent Piazza.

Simpson and Piazza spent the entire Emmys weekend together, hitting several red carpets and post-awards show bashes hand-in-hand. Another sign the couple is getting serious: She met Piazza's parents!