That flightless birds are descended from birds that could fly is commonly accepted among scientists. What is not completely clear, however, is why these birds lost the ability to fly. One plausible hypothesis suggests that when some ancient birds colonized habitats that lacked predators, they no longer needed the adaptation of flight to escape. Over time other more adaptive traits were favored by natural selection, while flight was not. Thus flightlessness was passed on to…

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Physical Characteristics

Extinct Species

Living Species