I may be wrong, and please, if someone knows more, please correct me. But, T'Girl, it is my understanding that no lizard is structured to remain in an upright position, the way some dinosaurs did. The picture you showed of this lizard upright would be akin to a dog standing on his hind legs. Sure, he can do it, but it's not what he was designed for.
Again, if I'm wrong, please let me know.