This painting, for some reason, is known by the title of El Greco, an artist Sharp totally disregarded and whose style this does not particularly resemble.

Sharp painted a smaller work than this titled  John and the Buffalo Skull – Firelight and featured it in his annual Cincinnati exhibition at the Traxel Art Galleries in 1923. It measured only 16 x 20".

This larger canvas pictures John Hunting Son in supplication before a large bison skull. John smudges smoke with an eagle feather fan. It is not unreasonable to consider that this and the smaller 1923 version might be related.