HOW DO THEY DO THAT?
That's what I'd like to know.
Going off on a tangent here, but there's only been Dinosaur (2000) which has some pretty spectacular animation mixed with live action backgrounds and the more recent Ice Age: Dawn of the Dinosaurs (2009). And I think that's it as far as dinosaurs are concerned. So I'm hoping they'll knock it out the park with
The Good Dinosaur when it eventually comes out.
Below is a little short I found online.