the model is great. This could be made much more photorealistic with a bit more work. The model needs a more detailed texture and more definition around the legs to define some muscles. I don't think the direction of the shadow cast by the dino matches that on the background image. Furthermore you could probably play around with the camera settings/position/ scale of the dino to make it fit much better into the backround. You could then doctor it a bit in your image editor, like add some dirt covering some of the foot so that it is sinking into the sand/ blur him a bit (maybe depth of field) as he is too crisp compared to background.