This hatchling appears to be... dead?

Perhaps not. It seems to be active during the night.

Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it typically marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.

Eztli Cryptdweller is the only undead hatchling in the cave for the moment being. She does not get along very well with the living hatchlings and prefers to spend her time at a nearby crypt, where she lies curled up on the coffin.