>>38190698They probably just atrophied. Zweilous already has fucked-up hind legs, and its forelimbs presumably became Hydreigon's arm-heads, so it probably becomes increasingly reliant on the initial pair of wings it has as a Zweilous to move around to the point where it can't get around without using them to push itself around a bit as it approaches evolution.
Honestly the entire Deino line is a prolonged exercise in suffering. I don't think any other Pokemon family has as much pain baked into their life cycle as they do.
