Dinosaurs and Modern Animals are Birds of a Feather
I read with interest the Oct. 27 news article “Feathered dinosaur bore a mask like a raccoon’s,” about the fossil of Sinosauropteryx, the small dinosaur from the Cretaceous having “feathery fluff” that had been discovered in 1996. However, other than saying that the find “helped cement the idea that birds are living, avian dinosaurs,” the article made no mention of the fact that several fossils of other species of small, bipedal, feathered dinosaurs were subsequently found, some having actual wings with feathers that were very similar to those of present-day birds. Not mentioning that fact might have left some readers dubious about the idea that birds have dinosaur ancestry. In fact, even before those finds, Archaeopteryx, the first fossil of which was discovered in 1861, was actually a small, bipedal, feathered, winged dinosaur.
It should be made clear that the skeletons of these avian progenitors were still typically dinosaur-like. The only significant difference between their skeletons and those of other bipedal dinosaurs is that the digits of the forelimb — which were still separate instead of fused together as in present-day birds — were lengthened to form the wings. Most likely, though, because they did not have a sternum as modern birds do for muscle attachment, their mode of flight was likely gliding instead of powered.