Pack Animal Design

Some of the sketches I've done of the pack animal, which so far is the furthest along in design.  I have some ideas for colouration, what I'm having some trouble deciding on the the horn design.  At first I was thinking of going for broad, flat horns that would act somewhat like heat fans, (similar to a stegosaurus' spines, which is also the reasoning behind those spiky protrusions on it's back and hindquarters) however I'm also kicking around the idea of making it like ceratopsia fans (upper right image, though I think I prefer a more ox-like or bovine-esque face to a dinosaur-like one, such as in the upper right and lower right sketches)

You can see two similar sketches here of the creature in the same pose; the more sketchy one is the first sketch I did, I originally drew it more sleek but I decided to give it some bulk, I also added ears, which may or may not stay, but I think I'll keep them.

I still might tweak this a bit more, particularly the spines on it's back.

Critique is appreciated.


Some other stuff I'm looking at:

Saiga Antelope: They have funny noses
Four-horned Antelope: These little guys are cute
 Cama: A cross between a llama and a camel, there's no image in the article,that's what Google Image Search is for.
Vulture
Pterosaur
Xerocole: I learned a new word :D
Thermoregulation
Hydroscopic