Complex sentence: Haast's eagle has sometimes been portrayed incorrectly as having evolved toward flightlessness, but this is not so; rather it represents a departure from the mode of its ancestors' soaring flight, toward higher wing loading and the species probably had very broad wings.
Split into simpler sentences: Haast's eagle has sometimes been portrayed incorrectly as having evolved toward flightlessness, but this is not so. Rather it represents a departure from the mode of its ancestors' soaring flight, toward higher wing loading and the species probably had very broad wings.