Tried another artprompt tonight:
“The head of this hard-plated reptilian beast seems to be completely mouth”
I immediately thought of some bulky, heavy-shelled monster with a long jaw brimming full of teeth; other features would include beady little eyes and bad attitude. That seemed like low-hanging fruit, so I tried to do something a little different, first trying something only relatively completely mouth, the third head from the left.
I kind of thought my way around it a few times, drawing the bottommost head so I could get that big-mouthed silhouette out of my brain, but then thought of a few others concepts, namely the very wide head and the immense underslung jaw. If I could have come up with something that was clearly reptilian and herbivorous, I would have done that too, but I was at a loss.