What are the two characteristic features present in the Aves (birds)?

cbse
diversityinliving

#1

What are the two characteristic features present in the Aves (birds)? Why are the bones of birds so light?


#2

The two characteristic features of birds are:
(i) Forelimbs are modified into wings.
(ii) Jaws are modified to form beak.The bones of birds are so light because they are pneumatic bones that contain air spaces. This allows them to fly high in the sky.