The Origin of Birds was a book authored by Gerhard Heilmann in that he argued that birds could not have descended from dinosaurs (predominantly because dinosaurs lacked clavicles, or so he thought), and he therefore favored the idea that birds originated from the so-called 'pseudosuchians': primitive archosaurs that were also thought ancestral to dinosaurs and crocodilians. Image:Mantell's Iguanodon restoration.jpg This article is a . You can help My English Wiki by expanding it.