I just added the following to the Alto Trombone History Timeline. I will also be adding it to the Trombone History Timeline, collection of angel-trombonists, and map of trombone iconography.

16th century—Toledo, Spain: A fresco located in the courtyard called “de la Mona” at the Convent of las Comendadoras del Apóstol Santiago features numerous angel musicians, including an angel playing an instrument diminutive enough in proportion to its player to be an alto trombone or smaller (see detail and full image below; public domain).