For sculpting reference, I used a number of diagrams of proposed pterosaur musculature as a loose guide. I also threw in my own knowledge of crocodylian musculature to help sculpt in the major muscle masses. A lot of the fine detail was influenced by birds, a few minor details from bats, and even some influence from lizards. I looked at a lot of pelicans, cormorants, parrots, and condors to try to get some nice face wrinkles. There's a lot of detailed skin texture which is kind of difficult to see on the wider images (click for larger view).
Now I need to work on getting the diffuse, displacement, and normal maps to properly transfer to Houdini so I can move on from texturing.