Nice!
Nice work overall, I love how the body fades to white on the left.
Iguanas are the biggest contributers to dragons in film. Most of the time when you see a dragon, if it is kickass, it has some Iguana in it's gene pool. I've spent much time poring over the facial scale details of Iguanas and Bearded Dragons, but I digress... I understand the scales are hinted and this is a quick sketch, but the arm could use a bit more loving on the overall forms. There are subtle biceps and triceps under all those scales, and the forearm is usually even more muscular.
!Cheers
PS: and can you link to your reference please? I'm really surprised there is a line of "hairs" running along the arm, I never noticed those...are they little spikes? Maybe it's a type of Iguana I've yet to see