I looked at the left-side of the tail, and the shading made it look just fine, to me. But went back and checked the right side, and it just seems the placement of the..spines..spiny..things are off.

Also, I retract my statement about the ear, I see now that it is also a spiny..thing. While I don't know much about dragon/reptile anatomy - or any anatomy at all, really - I assume that the spines are supposed to be right over the actual spine of the dragon? And in that case, since the tail is an extrension of the spine, it just curves over too soon.
Whenthe tail comes into sight from around the rock, they shouldn't be on the top or front yet, but on the back-side fo the tail, then as it comes around to the front of the rock, the spines would be clearly visable. Being how big the.. spiny things are, they probably would be slightly visable just above the tail, when it comes around?
Err, if you can make sense of any of that. Maybe this'll explain what I'm talking about more?

Though, I'd wait until an actual artist got here first. XD
Still, lovely art! I can't believe I missed this thread for so long.