Subject: How did dinosaurs, particularily sauropods work?

Sauropod skeletons, as well as those of dinosaurs such as the stegosauraus 
were really, really big, and had really little heads (which makes sense, 
'cause otherwise they would have fallen over).  I read years ago (not 
quoting a source, just in general) that the stegosauraus had a brain about 
the size of a walnut, or in that vicinity.  Are there any examples in 
nature that support an animal of that size existing with that cranial 
capacity? Even a giraffe has a much larger brain, proportionately speaking.  
Could a brain the size of a baseball coordinate the movements of a 
gigantic, complicated animal like a dinosaur?

Re: How did dinosaurs, particularily sauropods work?