An early drawing of the bogthumper, then called the grumplump before I confused the two names. This was also before the lumps were established to have an upper and lower pair of flanges, so the face looks a little different from the later lumps.
A few minor differences are the lack of the horns above the eyes (given to make it more similar to the other horned lumps) and making its feathers extend nearly all the way down the body instead of only at the upper half.