When I first looked at this I thought about Cleveland Indians,, and the Pontiac Chieftan !! I would say 40`s or 50`s on it !! Pic says the image was copied from something else,, then colored in !! An artist would have made a better use of the space !! Pic is too small for the size of the antler !! Basically this is just colored in the lines !! This appears to have been done with a water based paint,, not oils !! Reason I say that is that water based paint just sits on the surface,,an oil would have absorbed into the antler somewhat,,I see no shadows where that happened !! Water based paint would have flaked off like yours did if not sealed afterward !!