The scientific class of the bird is Aves, each specific breed of bird has its own scientific name. Some scientists believe birds were coexisting with the dinosaurs, while some believe that they were not at all in the same time period. Most scientists actually believe that birds evolved from dinosaurs, more specifically from two-legged running dinosaurs called Theropods. This theory was born because of the discovery of Archaeopteryx, the oldest bird fossil found in Germany in the 1860's.
For more information about the evolution of birds, see "Evolution/History of Birds" under the "Recommended links and photos" section
For more information about the evolution of birds, see "Evolution/History of Birds" under the "Recommended links and photos" section