ABSTRACT
Thinking of birds as a type of dinosaur is hard for many to grasp. This chapter begins by looking at the phylogeny of the group Maniraptoriformes, the lineage in Coelurosauria that leads to modern birds. From there, it covers the Avialae clade and the characteristics of avians followed by a discussion of the adaptations for powered flying. The chapter concludes by examining hypotheses of how flight was obtained in a lineage of maniraptoran dinosaurs and compares these ideas to flight in other vertebrates, including mammals (bats) and archosaurs (pterosaurs). Various hypotheses put forth for achievement of flight in this lineage are discussed, and the evidence supporting a “ground up” versus a “trees down” hypothesis for the origin of flight is evaluated.
