InhaltsangabeIntroduction.- Institutional abbreviations.- Comparison: general information about the main taxa to be compared in the present paper.- Phylogenetic analysis: review of available phylogenetic hypotheses about the origin of birds, discussing their respective logical bases and discussion of characters used for their support.- Systematic Paleontology: systematic arrangement.- Discussion.Evolution of feathers and wings among basal paravians. Osteological and integumental modifications related to the origin of flight.- Body size increase and loss of flying capabilities among paravians.- Independent origin of flying capabilities among paravians.- Averaptoran radiation and center of origin of birds.- Bibliography.- Character list.

Fernando Emilio Novas is an Argentine paleontologist working for the Comparative Anatomy Department of the Bernardino Rivadavia Natural History Argentine Museum in Buenos Aires. Novas holds a PhD in Natural sciences. Working for the CONICET, he described or co-described many dinosaurs, among them Abelisaurus, Aniksosaurus, Aragosaurus, Austroraptor, Megaraptor, Neuquenraptor, Orkoraptor, Patagonykus, Unenlagia, Araucanoraptor, Skorpiovenator, Tyrannotitan, Talenkauen, and Puertasaurus, most from the Patagonia region of Argentina.