Now I know what I want for my daughter's second birthday party- a rhino pinata! :). I love the gesture of your character's spine.
I did a quick paint-over to see if I could make the rhino more stocky or chubby, like a baby rhino. It was just feeling too lean and skinny, like a small donkey or even a deer. I linked to a photo of a baby rhino just for reference to show the proportions. You can stylize animals in lots of different directions, but the goal should be to preserve what is uniquely characteristic of that animal (assuming you want people to recognize that it is, in fact, a rhino—if you're trying to invent an alien species, that's a different story). Anyway, just a suggestion!