For a good while I wasn't able to find anything to crit but then I figured one out.
The whole picture lacks a certain amount of depth. For instance, up until your last comment, I thought the sky was a cliff face about ten feet away from the dinosaur. That the volcano was a texture on the cliff face, that the smoke was comet shadows on the cliff face, and the trees were little shrubs about one foot away from the cliff face. That's a lot of cliff face XD Uhm, so anyways, the point is, I don't think it transpires depth the way it's meant to.
To fix that, I would thin out the thick outline that seperates the horizon. The relative thickness to the dinosaur's outline is misleading. Perhaps you can shade each object creating the depth differently rather than all the same. The trees, volcano, grass and dinosaur have all been shaded the exact same way. Which is a big reason as to why you'd think they were all relatively close to you. The sky has a very brown hue to it right now, which is partially why I mistook it for a wall originally. I kind of like the palette so I don't recommend changing it. So, my solution for that would be to somehow transpire that's a sky or...maybe it will look more like a sky when the other issues are taken care of.
Other than the depth issue I think it's good.