For a moment I thought he was sitting on someone else's enormous tail - the details in the rock looked "scalish" to me at first. It's very well done, and I'm impressed with the light wash - the reflections of the setting sun on his body are perfect.
Dragon anthros are really lovely! I love how the anatomy has turned out. The scaling looks very nice, too, I like how you did it, especially on the legs. And the head looks so good, the perspective works really well and the horns are just pure love. I adore your colour usage too. The colours and colouring look amazing! I love how you have painted the sky. Lovely work!