I love the idea of Saurials and given the background from FR they could easily end up on any planet (I seem to recall Moander brought them from another prime material plane)
Anyway other then kudos for suggesting the idea I suggest you make the hornheads a large creature instead of medium, I think they are supposed to be on par with ogres in size. I'd also add natural attacks for all of them (as suggested above) and give them cold vulnerability to balance out the natural attacks they get.