The Evolution of Birds with Implications from New Fossil Evidences

Abstract

Birds have evolved on the planet for over 150 million years and become the most speciose clade of modern vertebrates. Their biological success has been ascribed to important evolutionary novelties including feathers, powered flight, and respiratory system, some of which have a deep evolutionary history even before the origin of birds. The last two decades have witnessed a wealth of exceptionally preserved feathered non-avian dinosaurs and primitive birds, which provide the most compelling evidence supporting the hypothesis that birds are descended from theropod dinosaurs. A handful of Mesozoic bird fossils have demonstrated how birds achieved their enormous biodiversity after diverging from their theropod relatives. On basis of recent fossil discoveries, we review how these new findings add to our understanding of the early avian evolution.