The Missouri outline shape on this marker is similar to the shape first seen on Missouri 152 in Liberty. In this instance, Missouri 149 was re-routed in 2005 during construction on US 36 in Macon County. Even more unusual is the font. It's definitely not FWHA Series B, C, or D! There were other examples of detour markers along this route as well.
This photograph was taken in September 2005.