Good luck catching him. He was a quick, resourceful little bugger. I suppose the Willosaurus was pretty cool, for the facts that Will Wright created it, and also because it was one of the more 'natural' looking creatures. I'm sorry, but I don't see how a buttface or a tweety bird could evolve, or even survive in the wild. Yeah they're cool, but they're just too wierd lookin.
Looks aren't everything! That huge bird could have a future if dirigated successfully by your expertise! Even some of the ugliest species managed to make their way through evolution, look at the monkey!