I think the "Rank" system means paladins,mercenaries etc.As for dragons,you need new skeletons.It is not impossible,but it is very hard.Let's take a human bone:
<Bone name="hb_abdomen" bone_mass="10"> <Bodies> <body type="capsule" radius="0.14" pos_x="-0.04" pos2_x="0.04" pos_y="0.08" pos2_y="0.08" pos_z="-0.03" pos2_z="-0.03"/> </Bodies> </Bone>
What exactly are body type,radius,pos_x,pos2_x etc?I mean,you need to know how to define them.Anyway,it is not impossible.You have a horse and a human model.A dragon,in the "skeleton" similiarities,is a horse with wings,shorter frontal legs and that stands on his back legs(in gothic yes and this is animation part).