A great deal of effort has been placed on the century-old controversy of the origin of birds. This topic has been examined by analyzing fossil evidence from skeletons, eggs, and soft-tissue of many bird-like dinosaurs and primitive birds. In addition, this question has been addressed by using behavioral inferences derived from a series of exceptional fossil discoveries.
All this evidence strongly supports the notion that the closest relatives of birds are to be found among the carnivorous maniraptoran theropods—animals akin to the renowned Velociraptor. Our studies have also been extended to address the closely related question of the origin of avian flight, which we envisioned as originated within maniraptoran theropods capable of flapping their feathered forelimbs while running. Our contributions to the study of the origin of birds also include detailed analysis of a particular lineage of bird-like theropods, the short-armed alvarezsaurids.