User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-74.193.211.56-20121223184823/@comment-124.169.228.68-20130102112518

they don't really fly except to get out of traps. and you can't give up flight. it is a biological adaptation that occurs over an extended time span.

for example, a gravios can't wake up, decide it doesen't like its wings anymore and cut them of or burn them. as gravios uses them with less and less frequency the wings will become vestigal and lose their proper function. then they will not occur in future generations.