Birds and mammals have a constant body temperature. They are termed homoiothermal.
Sub class Eutheria :
Order: Rodentia: Small group of animals (Herbivorous and terrestrial), incisors long, sharp and chisel-shaped. Forelimbs shorter than the hind limbs, Example: Rat, squirrel.
Order: Chiroptera: These are flying mammals. Fore-limbs adapted for flight. Skin folds i.e. patagium works as wing. Example: Bat.
Order: Carnivora: Flesh-eating mammals. Large pointed and sharp canines to tear the flesh, Fingers with sharp claws, Example: Lion, Tiger, Cat, Dog.
Order: Primates: Highly developed Brain. The neck is mobile. Eyes are set forward in the dead to provide binocular vision. Limbs have five digits with flat nails. Two thoracic mammae (breasts) present. Example: Monkey, Apes, Man.
Order: Cetacea: Aquatic, fore-limbs are changed into paddles without neck and Fish-like shape but respiration by lungs. Example: whale.
Order: Proboscidea: Large, herbivorous, terrestrial. Fusion of upper lip and nose to form a long mobile trunk and only one pair of incisors in upper jaw which form huge tusks in males, Example: Elephant.
Order: Ungulata: Hoofed mammals, Herbivorous, Usually domesticated by man and Mammae are abdominal with teats. Example: Deer, Cows, Sheep.