Designed for Flight
Many textbooks tell young people today that birds are modified reptiles. Suppose, they say, that millions of years ago the scales on some reptiles began to fray along the edges. In time, they say, the frayed scales turned into feathers and birds were born.
The elegance and beauty of the feather make this story hard to believe. Can sticking a feather on a lizard produce a peacock? The bird's feather is only a small part of the complete flying system of the bird. Even with very careful planning and redesigning, a reptile doesn't have what it takes.
A bird needs massive breast muscles for flight. In some birds, 30 percent of the body weight of the bird is breast muscle. By comparison, in humans, breast muscles are only about 1 percent of body weight. A bird also needs an extremely high metabolism and blood pressure to deliver the energy those muscles need for flight. Birds have a higher metabolism than any other creature; they also have the necessary high blood pressure. Finally, as is well known, birds need light skeletons. The man-o'-war has a wingspan of seven feet. But its entire skeleton weighs only a few ounces – less than its feathers!
Even the most clever rebuilding of a reptile cannot produce a bird. In fact, birds have very little in common with reptiles. The entire being of the bird, from body to brain, has been specially designed for flight by a Creator who clearly knows everything there is to know about flight.