In birds, lightweight air-filled bones and a large four-chambered heart are examples of adaptations for what purpose?
mating
speed
long lifespan
flight
Birds are endothermic tetrapod vertebrates. They are bipedal and have wings and feathers. Their organ systems are adapted for flight. For example, they have light-weight air-filled bones and a large four-chambered heart. Birds also have relatively large brains and a high level of intelligence.