Question

The mallard duck possesses a keeled sternum. What is the function of this specialized bone structure?
A) To provide stability in water
B) To provide a site of attachment for the large flight muscles
C) To increase the body’s surface area for heat exchange
D) It is a weapon used in sexual competition between males

Answer 1

Hint:Bone structure of birds seems like a light, yet still strong bone structure is a requirement for flight. Bird bones are laced with air cavities. Their hollow bone structure to minimize weight. Sternum is the breastbone. Keel cedes an anchor to which a bird’s wing muscles attach, so providing adequate leverage for flight.

Complete answer:
Birds are archosaurs, and have ancestors with diapsid skulls. Birds skulls are highly specialized- mostly fused into one piece. A keel in bird anatomy is an augmentation of the sternum, which runs axially along the midline of the sternum and stretched outwards, perpendicular to the plane of ribs. The sternum has a keel- like projection to which the pectoral muscles attached. These muscles provide the all-important down stroke in powered flight. In contrast, flightless sternum.

So, keel sternum provides area for the large flight muscles to attach.

Thus, the correct answer is option (B).

Note:Birds have three types of flight muscles, they are pectoral muscles, accessory muscles, tensor muscles. Large flight muscles help in flying. Perching muscle helps with perching. Carina is another name of keel (plural: carinae), ratite is the group of flightless and mostly large and long-legged birds.