When Zodiac Dragon is put into your graveyard from the battlefield, you may return it to your hand.
Even though Zodiac Dragon is a Dragon, it doesn’t have flying.
If Zodiac Dragon is removed from the graveyard after the ability triggers but before it resolves, you can’t return it to your hand. Similarly, if a replacement effect has Zodiac Dragon move to a different zone instead of being put into the graveyard, the ability won’t trigger at all.