I'm extremely bored, so I did a quick redline..hope you don't mind.
These are all just suggestions, since I'm not 100% sure what would be completely anatomically correct.
I feel like the snout should be longer, but it doesn't have to be if you prefer it short. The bottom jaw seems a bit too big, in my eyes.
The chest/ribcage seems a tad sharp to me.
The wings can be horizontal, if you like, which would be like (s)he was trying to seem bigger, or about to fly away, I guess. xP
The ankles(mostly the left one) seem a bit thin to me.
I really like the playful mood of this drawing, and both the chicken's and the dragon's expressions.You draw feet so well; I'm jealous. xD Those spikes and the horns...they're just so amazing.
The spikes on the tail remind me of rose thorns. ^^
I really can't wait until this is finished and colored(if you are planning on finishing and stuff). :D