I know there has been a bit of worry from people who's Royals aren't eating at the moment that they can see their snakes spine. I want to reassure you that a snake's spine is literally the backbone of its body and will almost always be visible and in certain positions very prominent.
This is Duke, 700+ grams of muscle, a great body shape and in excellent condition.
As you can see laying on the floor the spine is visible runing down the centre of his back but not really sticking up.
While curled over my hand however the weight of his body against my hand pushes up his ribcage into a different position from a resting position and this has the effect of lifting the spine, the muscles are at work too which will further change the shape of the body too.
So as you can see if you can see the spine on Duke the spine isn't really the best way to judge the health of your snake.
I'm glad it helps, they were taken today, had him out and as he curled over my hand I just had to grab the camera and show that its normal as everyone knows what a beast Duke is.