Avialae is a term for birds and their immediate extinct ancestors. It is a clade of dinosaurs containing their only living representatives (birds) and whatever coelurosaurs are regarded as their ancestors. There are two ways it can be defined:
Definition by physical characters
Avialae is defined as a clade based on physical characteristics. Jacques Gauthier named Avialae in 1986 as all dinosaurs that possessed feathered wings used in flapping flight, and the birds that descended from them.
Branch-based definition
Several other authors use a similar, but branch-based, definition: all theropods closer to birds than to Deinonychus.
References
↑Gauthier, J. 1986. Saurischian monophyly and the origin of birds. In: K. Padian ed. The origin of birds and the evolution of flight. San Francisco: California, Acad.Sci. pp.1–55. (Mem.Calif.Acad.Sci.8.)
↑Gauthier J. and de Queiroz K. 2001. Feathered dinosaurs, flying dinosaurs, crown dinosaurs, and the name Aves. 7-41 in New perspectives on the origin and early evolution of birds: proceedings of the International Symposium in Honor of John H. Ostrom (J.A. Gauthier and L.F. Gall eds) Peabody Museum of Natural History, Yale University, New Haven, Connecticut.
↑Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds) 2004. The Dinosauria. 2nd ed, University of California Press.
↑Senter P. 2007. A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology, (doi:10.1017/S1477201907002143).
