I just added the below caption and picture to the Trombone History Timeline (16th century). The grip on the trombone is improbable, and the bell flare is highly unusual. It could be a matter of a restoration error, or it could be artistic license (or some combination).

1543—Piacenza, Italy: Angel musicians by Bernardino Gatti in the cupola of the Basilica di Santa Maria di Campagna include a trombone with an unusually wide bell flare (see below image; public domain).