Douglas Harper's Etymology Dictionary
ptero-
before vowels pter-, word-forming element in science meaning "feather; wing," from comb. form of Greek pteron "wing," from PIE *pt-ero- (cognates: Sanskrit patram "wing, feather," Old Church Slavonic pero "pen," Old Norse fjöðr, Old English feðer), from root *pet- "to rush; to fly" (see petition (n.))
Wiktionary
ptero-
pre. pertaining to wing or feather