Bird
. Bird, animal with feathers and wings . Birds are the only animals with feathers, although some other animals, such as insects and bats, also have wings. Nearly all birds can fly, and even flightless birds, such as ostriches and penguins , evolved from flying ancestors. Birds are members of a group of animals called vertebrates, which possess a spinal column or backbone. Other vertebrates are fish, amphibians, reptiles, and mammals. Many characteristics and behaviors of birds are distinct from all other animals, but there are some similarities. Like mammals , birds have four-chambered hearts and are warm-blooded—having a relatively constant body temperature that enables them to live in a wide variety of environments. Like reptiles , birds develop from embryos in eggs outside of the mother’s body This diagram illustrates some of the important anatomical structures common to birds. Many of these structures are adapted for greater efficiency in flying. The digital and wrist bones of th...