In birds,the external ear (pinna) is .......

Identify the vertebrate group of animals characterized by crop and gizzard in its digestive system.

Characteristic features such as a four-chambered heart,feathers,and pneumatic bones are applicable to which class of vertebrates?

Which of the following is a flightless bird?

Give scientific reason: Birds show adaptations for flight.

Students of class $XII$ were given a list of the following characters: clawed toes,curved beak,feathers,pneumatic bones,wings,and fur. In this list,how many are volant adaptations?