Tom Mix had left the Selig Polyscope Corporation, where he made a series of short westerns, at the end of 1916. Throughout 1917, he made short films for the Fox Film Corporation. In January, 1918, Fox released his first feature film, Cupid's Roundup. Tom Mix was on his way to becoming the biggest cowboy star in silent movies.
Motion Picture World, 05-January-1918
"...his first picture as a star in Western dramas..."
Motion Picture World, 19-January-1918
"The former comedian is cast this time as a rich man's son..." Comedian? There was a lot of comedy in the Selig films.