Linked from
The 20 pages that link to Evolution of birds, each with the reason it gives.
Jehol BiotaRelated: Jehol birds and close relatives document early stages of avian evolution.
SaurischiaRelated: It traces the living continuation of the saurischian theropod lineage.
FurculaRelated: The furcula is a shared skeletal feature tracing dinosaur ancestry in birds.
NeornithesRelated: Neornithes is the surviving crown branch of that long evolutionary history.
Evolution of reptilesRelated: It is the surviving continuation of one major dinosaur lineage.
Owlet-nightjarRelated: Owlet-nightjars' placement among bird lineages is still studied.