I guess that the stegosauria throut pouches, didn't just pop up at _Stegosaurus_, somewhere it had to evolve from! Whith other stegosaurian species had that bony pouch? Did perhaps the most primitive, _Huayangosaurus_ have one? -DinosØMP Meet me, and the dinosaurs at http://home.sn.no/~enrique/dinoklad.htm We'll be waiting for you.