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.

PHOTOS: Pete and Ashlee, the way they were

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.

PHOTOS: Stars who romance models

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.

PHOTOS: Ashlee and Jessica through the years

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!

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