Comment on Pern Dragon Skeleton by bronze-dragonrider

Since it says that they rely on the ball-and-socket joints to keep the knees from dislocating, wouldn't that imply that the knees are a ball-and-socket joint?

On the next page the knees are clearly ball-and-socket, but I have no idea if elbows were supposed to be as well.

But anyway, even if they are supposed to have them, it makes no sense to begin with, lol.