Evolution of birds to create variations on wild species. In some birds this is limited to color variations, while others are bred for larger egg or meat production, for flightlessness or other characteristics. Evolution of birds The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropoda dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur "Archaeopteryx lithographica" from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current
Specimens of Archaeopteryx "Archaeopteryx" likely indicated it had very little flight ability. The furcula (wishbone) is well-preserved and lies between the scapulae; its boomerang-like shape reveals a 75-degree angle between its branches. De Beer identified a compressed mass of bone as a sternum in the London specimen, but later researchers disputed this as more likely to be a concretion of vertebrae encrusted by calcite. That "Archaeopteryx" lacked a bony sternum is in agreement with the modern consensus that many specimens of "Archaeopteryx", including the London, likely represented immature animals whose sterna were still cartilaginous. The pelvic girdle is separated into its three components