Quote Originally Posted by Greyhawk View Post
More than one source identifies Au'Ra as the progeny of dragons. As well as the cranial projections (horns) are how they hear and have spatial recognition.

The descendance is supposed to be in dispute in the lore, as to whether or not they actually are, which I think adds a nice touch to the story for them. It's never been confirmed nor denied really.
I don't believe there is a single official source for this. The character creator blurb for the race outright states that their horns giving "enhanced hearing and spatial recognition" is not a draconian trait, and therefore a reason to consider them dissimilar.

The overall vibe of the description is that their appearance leads people to speculate that they are related to dragons, but this seems to be a coincidental sharing of visual traits that don't actually have the same function.

Meanwhile, the lorebook page about the race doesn't even raise the possibility.