We may believe that the progenitor of the ostrich genus had habits like those of the bustard, and that, as the size and weight of its body were increased during successive generations, its legs were used more and its wings less, until they became incapable of flight.
Uste izan dezakegu ostruken generoaren arbasoak basoiloaren antzeko ohiturak izan zituela, eta belaunaldiz belaunaldi haren gorputzaren tamainua eta pisua gehitu zirenean, hankak gehiago eta hegoak gutxiago erabili zituela, hegamenik gabe geratu arte.