In the animal kingdom, birds are the champions of song. But why do so many birds sing, and in so many amazing ways?

The earliest-known bird was Archaeopteryx, a species that lived around 150 million years ago, during the late Jurassic period. Archaeopteryx is considered to be a transitional fossil between birds and dinosaurs, and it provides important evidence for the evolution of birds from small, feathered theropod dinosaurs.