דו-רגליות – הבדלי גרסאות

{{בעבודה}}[[קובץ:Common_ostrich_(Struthio_camelus_australis)_male_running_composite.jpg|ממוזער|250x250 פיקסלים| ה[[יעניים|יען]], בעל-החיים הדו-רגלי הקיים המהיר ביותר מגיע ל-70 קמ"ש <ref name="Stewart2006">{{Cite web|last=Stewart|first=D.|title=A Bird Like No Other|website=[[National Wildlife]]|publisher=[[National Wildlife Federation]]|date=2006-08-01|accessdate=2014-05-30|url=http://www.nwf.org/News-and-Magazines/National-Wildlife/Birds/Archives/2006/A-Bird-Like-No-Other.aspx|archiveurl=https://web.archive.org/web/20120209033650/http://www.nwf.org/News-and-Magazines/National-Wildlife/Birds/Archives/2006/A-Bird-Like-No-Other.aspx|archivedate=2012-02-09}}</ref><ref name="Davies">{{Cite encyclopedia|last=Davies|first=S.J.J.F.|editor-last=Hutchins|editor-first=Michael|encyclopedia=Grzimek's Animal Life Encyclopedia|title=Birds I Tinamous and Ratites to Hoatzins|edition=2nd|year=2003|publisher=Gale Group|volume=8|location=Farmington Hills, MI|isbn=978-0-7876-5784-0|pages=99–101}}</ref> ]]