I've lamented this before. Just today... a few hours ago, no less... I finished reading the 7th Dresden Files book, Dead Beat. As the title implies, this one features necromancers and undead.
One character got the very bright idea of animating Sue. Yes, that Sue, the most complete and largest Tyrannosaurus rex skeleton ever discovered, and sitting in the Field Museum in Chicago (actually, I'm not certain if that's where Sue is these days. She went on a roadshow for a while, and I've lost track of her location. But that's where she was in the book.)
And what do you do with an undead dinosaur? You strap saddles on her back and ride her through the streets of Chicago to go munch on the other characters wimpy regular zombies and specters, of course.
*sigh* Whenever I think I have a really cool idea that's actually kinda original, I find that someone else has already done it. Rampaging undead dinosaurs? Cross that one off the list.