Nice wyvern!! When you draw dragons, do you draw upon earlier depictions of dragons for information on dragon anatomy or do you study the anatomy of animals like lizards, snakes, birds, bats, etc.? It is hard to draw something without a clear idea of how it works, but we can't exactly go out and study a real dragon. For dragons, I think that studying the anatomy of flying creatures like birds and bats is important, especially for details like how the wings attach to the body.
Pterosaurs- I should have thought of that. Pterosaur skeletons were said to be dragon bones in China, if I remember correctly. I begin thinking about what creatures I should study for the anatomy of fantastic creatures when I was thinking about how to draw a dragon- and I realized that I didn't know exactly what a dragon's shoulders look like, or how the wings connect to the rest of the dragon's body!!