Mesozoic Birds

AbstractBirds are living dinosaurs, an evolutionary transition increasingly well documented in the abundant fossil record of Mesozoic birds. The avian fossil record begins 150 Ma (million years ago) in the late Jurassic, and for the next 85 million years, birds experienced an evolutionary radiation resulting in a wide range of body forms and lifestyles, occupying all continents and many different environments. This Mesozoic radiation culminated in the appearance of modern birds, Neornithes, in the late Cretaceous, and the loss of several archaic groups during the mass extinction event at the end of this period.Key ConceptsBirds evolved from maniraptoran theropod dinosaurs during the middle of the Mesozoic Era, over 150 Ma (million years ago).Many unique adaptations of modern birds, from flight feathers to coloured eggs, evolved amongst their dinosaurian predecessors.A broad diversity of pre‐modern birds lived during the Cretaceous Period, their fossil record is well known from about 131 to 66 Ma.The Mesozoic radiation of pre‐modern birds paralleled many aspects of the biology of their living counterparts.Neornithes, or modern birds, originated in the late Cretaceous, were the only group of birds to survive the extinction event at the end of this period, and went on to diversify into the abundant forms seen today.