This is a very clever composition. The stream of air bubbles escaping from the mouth is a great touch! Just when you thought it was safe to go back into the water...
I think it could use a little more texture, but nevertheless, great work!
anyhoo, you know what would be cool is if you added a fish in its mouth w/blood comin out, but then again they might not want that 4 the cover
I'm having a contest (a good one now I hope)
Just a minor repair: aren't there too many fishes around, beeing a Nothosaur carnivorous?
Anyway, great job, I really like how you did all the shadows/highlights relation.