Penguin ancestors were able to fly, but they lost that ability quickly after the demise of the large dinosaurs. The oldest known penguin, with fossils dating to around 60 million years ago, was already a flightless swimmers with stubby wings. Modern penguins retain signatures of their airborne relatives, including wing bones, a pointy keeled breastbone for wing muscle attachments, and feathers. Losing flight made penguins better suited to their environment, because it meant that the birds could get bigger.
“I often consider [losing flight] a great breakthrough in penguin evolution,” says Daniel Ksepka, a vertebrate paleontologist and evolutionary biologist at the Bruce Museum in Connecticut. Flightless penguins evolved bigger muscles to better power through the water, denser bones that added strength and reduced buoyancy, and shorter, stiffer wings for more powerful swimming strokes with less drag. “Getting larger makes them more efficient at conserving heat, capable of deeper and longer dives, and opens the door to targeting larger prey,” says Ksepka.
read more: news.nationalgeographic.com/2016/10/reverse-evolution-explained-hagfish-penguins-snakes-science/
article: Jenny Morber
photo: Tui de Roy, Minden Pictures, National Geographic Creative