Feathers with smooth barbules but no hooked barbules.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> | Feathers with smooth barbules but no hooked barbules.<ref>Wile, Dr. Jay L. ''Exploring Creation With Biology''. Apologia Educational Ministries, Inc. 1998</ref> |