On the evolution of birds and avian flight. Feduccia is best known for his criticisms of the hypothesis, accepted by many paleontologists, that birds originated from and are deeply nested within Theropoda, and are therefore living theropod dinosaurs. "He has argued for an alternative theory in which birds share a common stem-ancestor with theropod dinosaurs among more basal archosaurian lineages, with birds originating from small arboreal archosaurs in the Triassic" (Wikipedia article on Alan Feduccia, accessed 04-2017).