Added the below images and caption to the Alto Trombone Timeline. It’s quite a beautiful painting. The other instruments “underfoot” are a shawm and a recorder. The trombone appears to be an alto, given its size relative to the things around it (the instruments, most importantly, but also the music and the man’s leg), although how literal the visual depiction was intended to be is always the question.
c. 1650—Italy: Swiss-born artist Pier Francesco Mola includes a trombone in his painting, Young Musician Playing a Viola da Gamba. Although it is impossible determine with certainty, the instrument may be an alto trombone, given its size relative to the surrounding instruments and music pages (see facing detail and full image, below; public domain) (Mola 161).
An update from Patryk Frankowski, senior assistant at the 