RG> Question: Why do we never find fossils of these "short giraffes?"

     You do not because you don't know where to look. Try a
     paleontology text.

     I suppose you'll get lost on your way there, so here's a few
     citations for you to mull:

     Genus _Samotherium_, a Pliocene "short necked" giraffe.
     Genus _Paleotragus_, a Miocene "short necked" giraffe.
     Genus _Sivatherium_, an Eocene "short necked" giraffe.

     Oh, and BTW, ever heard of the okapi? It's a modern equivalent
     of a short-necked giraffe.