That’s a beautiful picture!

Ptyra and Ada look fantastic, as do all of the character’s expressions. And I love how you made the image of Pterano and Ava translucent (slightly more so in some areas than others) to show that it’s a dream vision. The night sky also looks gorgeous.
You might be right about gray being a better color for the rock, but on the other hand, I personally think that the version you have now compliments Ptyra’s color scheme. It would probably look good either way.

As much as I hate to say it, I don’t think Pterano looks as good as the other characters, (apart from his eyes). The corner of his mouth looks too far back relative to his eye, and the line of his mouth is a little wavy towards the back. There’s also that little blurry lump on his forearm, and the top of his head looks a bit overly domed.
I also have to say that the outline between the egg and Ptyra’s wing looks really strange. Personally, I think it should be removed. Alternatively, you could outline the entire egg, but then the egg in the dream image would have to be outlined too. (Then again, that would make the egg in the dream more visible, which might be a positive.)
By the way, just an observation: I've noticed that you sometimes draw Ptyra with claws, sometimes without, but her hands and feet (as with those of most of the flyers you draw) are always the same color as the limbs they are attached to. In LBT, it seems that flyers that lack visible claws, such as Petrie’s mother, have dark-colored hands and feet. Any particular reason for this?
Oh, and just in case it’s useful, the archetypical domehead (the one most commonly seen in LBT, with the little horns on its snout) is
Pachycephalosaurus. However, the pair that appears in the TV episodes “The Cave Of Many Voices” and “The Great Log-Running Game” more closely resemble
Stegoceras or
Prenocephale.