Evolution of birds 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 consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked "reptile" clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous-Tertiary
Specimens of Archaeopteryx Justice in Karlsruhe, which upheld the Superior District Court's decision in 2003, bringing a 14-year lawsuit to a close and earning the sixth "Archaeopteryx" specimen its name of Solnhofen. The Solnhofen specimen represents the largest "Archaeopteryx" individual known. It is represented by a nearly-complete skeleton on a plate sized 39 x 52 cm. There is no counterslab associated with this specimen. The skeleton shows a death posture typical of theropods and especially similar to that of the Eichstätt specimen. The animal's carcass was likely deposited and buried completely articulated. Despite the specimen's skeletal completion, plumage traces are very faint and