Pygostylia

Left: the reptilian tail of Archaeopteryx. Right: the tail of a modern bird. The last tail vertebrae are fused to form a pygostyle.

The taxon Pygostylia refers to a group within the Birds (class Aves), which compared to other birds such as Archaeopteryx is characterized to a pygostyle by a shortened bony tail and the fusion of the last lumbar vertebrae. Other characteristics for the diagnosis of the group a number of seven or more pelvic vertebrae ( Sakralia ) which are fused together in the so-called Synsacrum and extended raven bones ( coracoids ).

The Pygostylia include all extant bird groups and the most fossil. In discussion, the membership of the Oviraptorosaurier: In some species the last caudal vertebrae were fused into a pygostyle - like structure. Some paleontologists regard this feature as an indication that Oviraptorosaurier flightless descendants earlier ( airworthy ) were birds. Others doubt that the " pygostyle " the Oviraptorosaurier to the birds is homologous and ask this group to the " non-avian dinosaurs " ( a term used by Kladistikern concept of dinosaurs in the traditional sense, that is exclusively their descendants, the birds, says ).

Systematics of birds taking into account fossil bird groups

The systematics of birds presents itself, including the group Pygostylia and new findings on the family relationships of Mesozoic birds as follows:

Confuciusornithidae

? Oviraptorosaurier (not too loud birds Fastovsky and Weishampel 2005)

Enantiornithes

Patagopteryx

Vorona

Hesperornithiformes

Ichthyornithiformes

Neornithes ( " Aves " by Fastovsky and Weishampel 2005)

Archaeopterygidae

Rahonavis

Jeholornis

665882
de