Hesperornis regalis

Hesperornis regalis was a flightless bird whose wing bones were so underdeveloped they may not have been visible outside the skin. Except to lay eggs, the bird likely spent most of its time in the water. Standing, it would have been about 3 feet tall, but when diving it stretched out to about 6 feet in length from the tip of its beak to the tip of its feet.