Those of you with a keen eye for animators will recognize the work of Tom Golden, ace animator responsible for arguably the most recognizable piece of Popeye animation - the spinning star opening of the color Popeye cartoons from 1943 to 1957. (the animation also had an afterlife, re-used as the opening of the King Feature TV cartoons)
Golden's credits start appearing in the later Fleischer cartoons, where he animated for Dave Tendlar's crew. He moved to Al Eugster's crew for a few cartoons that were released in 1942, animated for one cartoon - 'Seein' Red White 'N' Blue' - for Jim Tyer's crew that was released in 1943, and then spent time in Nick Tafuri's short lived crew animating on 2 Popeye cartoons released in 1944 and 1946. Golden then returned to Tendlar's group, with his animation in the 1946 release 'Rodeo Romeo'. He later became a de facto director of his own crew.
The clips below are from - in chronological order - 'Fleets of Stren'th' (1942), 'Pitching Woo at the Zoo' (1944), 'Abusement Park' (1947), 'Popeye and the Pirates' (1947), and 'Pre-Hysterical Man' (1948).
Note in the last clip that Jack Mercer was still ad-libbing as late as 1948. There are a couple other cartoons from the mid Famous Studio period where Popeye ad-libs - debunking the myth that Mercer stopped completely once the Popeye cartoons started being produced by Famous.