Millions of years of evolutionary change have made the birds we see today very different from their early ancestors. As we move back in time along their evolutionary tree, the line between what is a bird and what is not becomes increasingly blurred.

Special features of living birds.

  • forelimbs adapted as wings
  • toothless beak with horny covering
  • enlarged sternum, most with a keel to which flight muscles attach
  • modified wrist (semilunate carpal) to allow folding of wing
  • reoriented shoulder to allow ‘flapping’ motion of forelimbs
  • wishbone (fused clavicles).

Other features include:

  • feathers
  • warm-bloodedness (endothermy)
  • hollow bones
  • loss of parts of the skeleton, particularly in the hand, foot, tail and skull
  • no claws on hands
  • pygostyle (fused tail vertebrae or Parson’s Nose)
  • restructured pelvis.

Feather formation

Feathers are formed by the outermost layer of skin. They are made of the protein keratin, the same substance that forms claws, hair, nails and scales. However, the chemical composition of the keratin differs among each of these.

Eolophus roseicapillus
A Galah is pictured in full flight, the camera angle from underneath. Its wide wingspan is a feature of the photo. The Galah has a pink underbelly which extends to a part of its wings. The majority of its wings are grey, however, with some black tips. Image: A D Trounson
© Australian Museum

Australian Bird Feather Texture

Australian Bird feathers taken in the Birds Of Australia exhibit on Level 2 of the Westpac Long Gallery.

Image: Abram Powell
© Australian Museum

Australian Raven skeletons
Corvus coronoides Vigors & Horsfield, 1827. Aust Ravens. Skeleton. Image: Ric Bozlan
© Australian Museum

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