The latest addition to the Trombone History Timeline (17th century, 2nd half) is found below. The slide of the trombone is obscured by a cloud.

1672—Salzburg, Austria: Frans de Neve’s Allegory of Fame, located in the ceiling of the Schöne Galerie of the Residence State Rooms, includes what appears to be a trombone (see below image; public domain) (special thanks to Richard Lyman).