Aves is a clade of sauropsids commonly known as birds. Living species are characterized by feathers, toothless beaks, and (for the majority of extant species) the ability to fly. They are the last surviving and considered the most diverse class of dinosaurs today, having over 11,000 different living species on earth. They are a member of the clade Archosauria, along with crocodiles, being the sole living members of it. Due to their deep placement within Dinosauria and Archosauria, birds are now considered to be reptiles by taxonomists.
Evolution and History[]
Birds are thought to have originally split off from a dinosaurian clade called Paraves, mainly composed of other theropods. Most birds at the time still had clawed wings and teeth, the prior trait still able to be found (to some degree) in birds of prey and fledglings of extant birds.
Furthermore, most were likely incapable of fully fledged flight, and were presumed to have glided instead. An early example being Archaeopteryx, often considered at the time of its discovery ‘the first bird’/‘missing link’ between non-avian dinosaurs and birds. Later studies show it was instead likely apart of Avialae (the clade housed outside Aves and considered by taxonomists as the broadest term for "Bird"), making the transitional species for Aves still absent.