I noticed that greater kobolds and kobold shamans in Nagafen's Lair killed while under the skeleton illusion from the Ignite Bones necromancer spell had the graphics of their corpse altered so it would look like the corpse of a Kobold with a Bat's head (the corpse of something that looks like this :
http://eqbeastiary.allakhazam.com/search.shtml?id=33355)