User blog comment:BannedLagiacrus/Wingdrake Discussion/@comment-24941009-20180223174807

Maybe Wingdrakes are small, slim relatives to Flying Wyverns, which are big and bulky for the most (Except for Remobra, which was reclassified as Snake Wyvern in the fourth generation; and Giggis, which are just baby Gigginoxen (not sure if that's the plural for Gigginox, sorry if I'm wrong)). I used to think they were pterosaurs, but I scrapped the idea because of their wings.

As for the criteria, maybe it's for creatures that are just that: small, slim and peaceful (for the most) Flying-Wyvern-like monsters.

BTW, the third name is wrong. It's Raphinos, not Rafinosu.