A penguin's black back and white belly are not fashion. They are counter-shading. From above, the dark back blends into deep water; from below, the pale belly blends toward surface light. Sharks, dolphins, and sperm whales use a similar trick.
Penguin waddling is not wasted motion. Force-plate work on emperor penguins shows side-to-side sway recovers mechanical energy; short legs are the costly part.
Anthropornis was not a 5-meter monster; fossils point to adult-human height. Waimanu in New Zealand and Antarctic fossils tell a calmer body-size story.
Penguins cannot fly because evolution traded flight for stronger swimming and diving. Their wings became stiff flippers, making the sky harder to use but turning the ocean into their main arena.
Penguins did not simply lose useful wings; they traded flight for underwater propulsion, a 60-million-year shift visible from Waimanu to modern emperors.