Yup we had one on LS. It was owned by an RPer, and was used to hunt reds. The GMS let the guy keep it. I believe what happened was that for one day, for some reason they were accidentally spawning tamable.
At the time VERY few people could tame dragons, or anything impressive, so not many got tamed. On LS, only the one I knew of. The guy kept it alive for a realllllllllly long time, this was back before the days of bonding, if a pet died it was dead, and it was used in fairly active pvp combat as well if I recall correctly. I don't remember what ever became of it. I think its name was Justice? Or maybe I am just imagining that part.
Humorously, greater dragons are quite a bit more powerful than ancient wyrms were. They are pretty close to being on par with AW's currently as well.