Really cool concept and design on this one, with more time taken for refinement I'd say you're on to something great. The spines get a bit loose and the grey tone along the mid thigh, and top of the lower back could use some shading, right now that solid plane suggests flatness when the area is very rounded. Also try tweaking the foot placement, as it right now they don't look grounded. The back foot Reaches lower on the page (read:closer to us) than the front one which is responsible for the grounding issue. Also the blacked out feet could be rendered, but if you did a refined version I'm sure that would come.
Also this part is just a personal suggestion, I'd lose the tusks, there's enough going on in the design that I think it won't feel like it's missing anything without them. Something to consider maybe, maybe not. Anyway cool design, I'd like to see it fully realized good job either way.