Scripture explicitly teaches that God made birds (and other air creatures) and sea creatures on Day 5 of Creation Week. He made land animals and man on Day 6. 1
Frances C James How Many Dinosaurs Are Birds? 29 May 20214
The claim is that birds evolved from small theropod dinosaurs
Thomas Huxley, known as Charles Darwin's bulldog in Victorian England, was the first to propose the idea that birds evolved from dinosaurs Whether or not dinosaurs were warm-blooded is still a matter of controversy
In spite of all this confidence that the problem of the origin of birds has been solved, strong grounds exist for regarding the issue as unsettled, and that is exactly the subject of Alan Feduccia's new book. He thinks not only that Archaeopteryx could fly but also that birds and avian flight evolved long before Archaeopteryx. Indeed, in his view, birds were already distributed worldwide at the time of Archaeopteryx. Feduccia's biggest issue is the neoflightless problem. He argues that some unknown number of flying and flightless birds are being misclassified as dinosaurs.
For flapping flight, the wing has to be lifted to get ready for the next downstroke. Birds accomplish this with an intricate pulley system—the supracoracoideus muscle pulls on its tendon, which winds around a ‘pulley’ comprising the coracoid and clavicle bones. The tendon is anchored to the humerus or upper arm/wing bone.
Special flow-through lung design
Bird lungs are very different from reptile lungs. A reptile lung is like a bellows, that is, air is breathed in, and blood takes up the oxygen and releases carbon dioxide. The stale air is then breathed out the same way it came in. Mammal lungs have a different internal structure, but also work like a bellows.
How would the bellows-style of reptile lungs evolve gradually into avian lungs? The hypothetical intermediate stages could not conceivably function properly, meaning the poor animal would be unable to breathe.
Casey Luskin Questioning Orthodoxy: Dr. Alan Feduccia Speaks on the Origin of Birds 11/29/04 3
Birds have digits 2-3-4, and theropods have digits 1-2-3. This is powerful evidence that birds couldn't have evolved from theropod dinos.
Also, the theropod --> bird hypothesis requires that birds evolved flight from the ground-up. If Caudipteryx has feathers but not for flight, Feduccia finds this explanation quite tenuous. Put simply, ground-up proponents say feathers were pre-adapted for flight but evolved originally for insulation. This is silly because feathers are perfectly suited for flight, and very energetically costly to produce. If insulation was all that was needed, hair would have done the job just fine and would NOT have been nearly so costly. It strains credibility to say feathers evolved for insulation.
Archaeopteryx probably cannot tell us much about the early origins of feathers and flight in true protobirds because Archaeopteryx was, in the modern sense, a bird.
Paleontologists have tried to turn Archaeopteryx into an earth-bound, feathered dinosaur. But it's not. It is a bird, a perching bird. And no amount of 'paleobabble' is going to change that.