Reading Feature Comics #45 and notice that the Rance Keane strip includes a character named Shark Egan which sounded a little familiar. Turns out that many of the characters in the story including the bad guy are all regular characters from Shark Egan's strip, only Shark Egan appeared in Popular Comics by Dell not Quality!! A case that it was coming from the same studio? The heroes would appear in Features #46 as well, Rance Keane's final story. It appears by looking at GCD, they had last appeared in Popular Comics #53, July of 1940, almost a full year before their appearance at Quality.
It also means that the metadata info is wrong in this regard, this is not the first appearance of Shark Egan et al. Just their first appearance at this company.