Aves:
1. Aves are totally adapted for the aerial mode of life.
2. Body is spindle shaped. Body is divisible into head, neck and trunk. There are two pairs of limbs. The forelimbs are modified to form wings for flight.
3. Digits have scales and claws.
4. The exoskeleton is in the form of feathers.
5. Jaws are modified into a beak.
6. Birds are oviparous. The eggs hatch into nestlings.
7. The incubation of eggs and feeding of nestlings is done by both parents.
8. Examples: Crow, Sparrow, Peacock, Parrot, Pigeon, Duck, Penguin, etc.
Mammalia:
1. Mammals are adapted for terrestrial life.
2. Body is not spindle shaped. It is divisible into head, neck, trunk and tail. There are two pairs of limbs. They are adapted for walking or running on the ground.
3. Digits have nails or hoofs. Few have claws.
4. The exoskeleton is in the form of fur, hair, wool, etc.
5. Jaws have teeth and they surround the mouth.
6. Mammals are viviparous. They give birth to live young ones. (Exception: Platypus)
7. Parental care is shown only by mother, who feeds, the babies with milk from mammary glands.
8. Examples: Cat, Dog, Tiger, Lion, Elephant, Human, Kangaroo, Dolphin, Bat, etc.
