Are birds really avian dinosaurs?

Robin and the Honey Badger respond: “Birds may be descendants of a primitive theropod but this does not mean that birds are theropod dinosaurs or even dinosaurs in any sense. Originating from an ancestor is not the same as being that ancestor. Evolution is about one organism evolving from another, not one organism remaining another. For example it’s now accepted that snakes evolved from primitive lizards but it would be absurd to claim that snakes are lizards, and nobody has done so. Similarly, equating birds with dinosaurs does not stand up to scrutiny because the anatomy has changed categorically in the transition. Bipedal dinosaurs kept balance by using a long, bony tail as a cantilever to the forequarters. By contrast, no bird has such a cantilever because all birds have a short, unrecognisably modified tail skeleton. Indeed, the reduction of the avian tail consistently distinguishes birds, living and extinct, from all dinosaurs. This transformation of the spine brought a revolution in locomotion, with vertical instead of horizontal oscillation around the centre of gravity. The product of this evolutionary innovation was Aves, which remains valid as a separate class notwithstanding its dinosaurian origins. With their exclusive combination of feathers and a short bony tail, birds are no longer any of their ancestral forms, whether fish, amphibian, archosaur, theropod, tetanuran, or coelurosaur. Instead of remaining dinosaurs, birds deserve to be distinguished by both conventional taxonomy and cladistic phylogeny. In fact, birds are birds, not dinosaurs.”