Question

with respect to the legs, the fifth toe has been lost and the first toe is pointed posteriorly, acting as a “prop” on the ground and allowing birds to perch on tree limbs. the many bones of each ankle are fused into a single tarsometatarsal bone that acts as a shock - absorber during landings. the location and articulation of each femur with the pelvic girdle helps to shift the weight of the animal forward, keeping its center of gravity over the feet. each wing bears three short fingers and a fused carpometacarpal bone. check your progress 1.1 what common feature of bird bones has made flight possible? 1.2 list five bones in the pigeon that are directly homologous to bones in humans. 1.3 list five bones in the pigeon that do not have direct homologues in humans. 1.4 what are three adaptations of birds for flying? respiratory system note dissection of the air sacs should be performed before dissection of the visceral organ systems using specially prepared specimens with latex injection of the air sacs and spaces. check with your instructor to see if a demonstration specimen is available with the respiratory system already dissected. procedure 1 position your specimen on its back with its ventral surface facing you, and use scissors to make a longitudinal incision along the midventral line of your specimen from the base of the neck to the cloaca, as depicted in the dissection diagram. 2 use a blunt probe to separate the skin and feathers from the underlying musculature of the breast and abdomen, being careful not to damage the crop, which lies just beneath the skin at the base of the neck. 3 next, use a scalpel to cut transversely through the middle of the pectoral muscle and underlying muscles. remove the pectoral musculature from the sternum. 4 use scissors to cut through the keel of the sternum and separate the underlying membranes from the bone.

Explanation:

1.1 Birds have lightweight, hollow bones which reduce their overall weight, facilitating flight.
1.2 Femur (thigh - bone), humerus (upper - arm bone), radius, ulna, metatarsals (foot bones) are homologous to human bones.
1.3 Tarsometatarsal bone (ankle - like fusion), carpometacarpal bone (wing - specific fusion), pygostyle (tail - related bone), quadrate bone (skull - related), coracoid bone (shoulder - related) have no direct human homologues.
1.4 Lightweight bones, wings with feathers for lift and maneuvering, and a strong pectoral muscle system for flapping are adaptations for flying.

Answer:

1.1 Lightweight, hollow bones.
1.2 Femur, humerus, radius, ulna, metatarsals.
1.3 Tarsometatarsal bone, carpometacarpal bone, pygostyle, quadrate bone, coracoid bone.
1.4 Lightweight bones, wings with feathers, strong pectoral muscles.