I've done many dino pics in my career. Either painted traditionally, in Photoshop, or rendered in a 3d program using pre-build models. Below is the first dinosaur I've ever sculpted entirely by myself, and textured, in Blender. An interesting exercise! This took me about four days, but I imagine with practice it'll get a fair bit faster.
3d model of Lambeosaurus sculpted by me in Blender. Better than my earlier T Rex but the hands are not right.