Question

Birds have bipedal locomotion as it is –
A) Increases rate of locomotion
B) Reduced weight
C) Spares forelimbs for flight
D) Provides more support to body

Answer 1

Bipedal locomotion is the movement of an animal on two legs while being in an upright position regardless of whether they are bipedal to begin with. Bipedal movement can be running, hopping or walking.

Complete answer:
In general, bipedal locomotion is the ability of an organism to move by two feets and two legs. Its benefit is that hands are free for carrying tools. Humans, birds and occasionally animals walk bipedally. Birds are very different in their way of life and habitat.
Style of bipedal locomotion changes with speed. For example, at low speeds humans tend to walk whereas runs go faster. Length changes as speed increases or decreases. Birds provide us with an opportunity to study the relationship between body size and bipedal locomotion function.
In birds, forelimbs are modified into wings for flight whereas hind limbs modified for walking or locomotion. That is why birds have bipedal locomotion because forelimbs are used for flying and thus hind limbs left for locomotion. They spare or invest their forelimbs for flight.

Thus the correct answer is option C. i.e., spares forelimbs for flight.

Additional information: As this is the case of aerial locomotion or movement so option A, B and D are incorrect. Birds have void (hollow) bones in them. Because of hollow bones they manage their weight. These bones help them to fly easily.
Yet the hind limbs of the birds are efficient in many manners such as take off, landing, swimming and walking. The limbs structure requires fitness and shock absorbers during landing or taking off.

Note: Sloth is considered as the world's slowest animal. Only six species of the sloth are existing all over the globe and these are divided into two varieties that is two-toed sloth and three-toed sloth.All the mammals have seven cervical vertebrae but two toed sloth have five to seven vertebrae while three-toed sloth have eight to nine cervical vertebrae. These extra vertebrae in three-toed sloth allowed them to rotate their neck up to 270 degrees.