While going to Polo Island to get Superior Alchemy (finally! ;) ) I mistook Hezrou for Polo and I've landed there. I was surprised to meet some Tyrannosaurs there. Well, I added them to the database under the Hezrou Island, but I don't know their drops. Here are their images (version 1:1 and scaled to 96x96, whichever fits better):
Valley Tyrannosaur lvl 77
Spraying Tyrannosaur lvl 78
Red Tyrannosaur lvl 77
Green Tyrannosaur lvl 78
Having a signature is like keeping a gremlin.
Just don't overfeed it, don't make it wishy-washy and you'll be a good responsible Signature Keeper :]