Adaptations for flight

Question 1

List the modifications to the skeletal system that allow birds to fly.

Answer 1

Feathers
Wings - tapered manus for primary feathers
Fused bones
Pneumatised bones
Enlarged sternum
Ventral Musculature
Triosseal canal

Question 2

How might the skeleton of a ratite differ?

Answer 2

Less ventral musculature and smaller sternum (keel/carina)

Question 3

What is the reason for havign a fused skeleton and which bones are often fused?

Answer 3

Provides stability against forces encountered during flight e.g. twisting. Tail fused to help manoeverability. Thoracic and pelvic vetebrae often fused, some long bones. Tail vetebrae fused to form the pygostyle.

Question 4

Which bones are pneumatised and how?

Answer 4

Long bones have projections of air sacs, as does the sternum and pelvis.
Skull has a honeycomb structure.

Question 5

What types of birds would you see the most extensive pneumatisation?

Answer 5

Good fliers

Question 6

What is the significance of the triosseal canal?

Answer 6

Allows heavy flight muscles to be held ventrally, clost to the birds centre of gravity, which gives stability during flight.

Question 7

What are the flight muscles and where do they insert?

Answer 7

Pectoralis - medial pectoral crest of the humerus

Supracoracoid - Dorsal tubercle of the humerus.

Question 8

Is there a reason why birds don’t need much dorsal musculature?

Answer 8

Since many of their dorsal skeleton is fused, there is no need to support it with muscle as well.

Question 9

In which types of birds would you see bigger of each flying muscle and why?

Answer 9

Gliders - big deep pectoral to keep wings steady against wind
Hovering/steep take off need better developed SC.