Avialae

Avialae is a theropod dinosaur group that includes modern birds and extinct close relatives. Its members are united by their position on the evolutionary branch leading to birds.

Theropoda: A diverse group of mostly bipedal saurischian dinosaurs that includes birds and many familiar meat-eating dinosaurs. Avialae is nested within this broader dinosaur group.
Archaeopteryx: A Late Jurassic feathered dinosaur known from fossils in southern Germany, often regarded as an early avialan. Its mixture of feathers, wings, teeth, and a long bony tail illustrates early avialan anatomy.
Evolution of bird flight: The evolutionary development of powered flight in birds from their non-flying dinosaur ancestors. Avialan fossils preserve a long sequence of anatomical changes associated with flight.
Dinosaur renaissance: A mid-to-late twentieth-century shift toward viewing dinosaurs as active animals and recognizing birds as dinosaurs. It helped establish the evolutionary framework in which Avialae is understood.
Avialae phylogeny: The inferred evolutionary branching relationships among avialans and their close theropod relatives. Different analyses place several Jurassic and Cretaceous fossils differently within the birdward branch.
Maniraptora: A theropod clade that includes birds and several groups of small-bodied dinosaurs with specialized forelimbs. Avialae belongs within this broader branch of theropod evolution.
Anchiornis: A small feathered paravian dinosaur from the Late Jurassic of China, known from exceptionally preserved fossils. Its placement near the base of Avialae highlights uncertainty about the group's earliest members.
Furcula: A fused pair of clavicles forming a forked bone in the shoulder girdle of birds and some other theropods. Its presence in early relatives links avialan flight anatomy to theropod ancestry.
John Ostrom: An American paleontologist whose study of Deinonychus helped revive the view of dinosaurs as active animals. His work strengthened arguments for close evolutionary links between birds and theropods.
Archaeopteryx controversy: The debate over Archaeopteryx's precise position among early birds and other paravian dinosaurs. Its classification can alter which traits and fossils mark the earliest Avialae.

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