I have always liked dragons, thinking them specially scary in water environments. I tried creating a real ancient kind of dragon, taking parts from the following: oar fish, T-Rex (specially the jaw), hippopotamus (the detail of how wide they can open their jaw), Pelican (that hanging pouch from their beak) and crocodile. I don't know if mixing so many details from so many animals was the best idea but I thought it was at the moment. I had to redraw him so many times to get it too look right that I lost track of how long I worked on the drawing.
The composition, environment and painting was done following the one and only Aaron Blaise in his "Let's Paint a Sea Creature!" live stream. I definitely recommend following his channel (as well as Facebook page) since he constantly uploads great lessons and streams to share with everyone.