Ornithurae

Ornithurae (meaning 'bird tails' in Greek) is the name of a natural group which includes all modern birds as well as their extinct relatives with plough-shaped pygostyles (†Ichthyornis, †Hesperornithes, †Limenavis). This is a bone at the end of the tail which allows the tail feathers to fan and retract. Gansus, from the Lower Cretaceous of China is the earliest known at 110 million years ago.

Ornithurae
Scientific classification
Kingdom:	Animalia
Superorder:	Dinosauria
Order:	Saurischia
(unranked):	Avialae

Simple classification:

• Birds
  • Ornithurae
    • Neornithes: modern birds: the most recent common ancestor of all living birds (class Aves) and all its descendants.
      • Palaeognathae (tinamous and flightless ratites)
      • Neognathae (all other modern birds)