1. Bear live young 
2. Maintain a constant body temperature  (warm blooded) 
3. Have differentiated teeth (canines, incisors, premolars, and molars) 
4. Will have two sets of teeth in their life 
5. Will have four limbs (two legs, two arms, fins and flippers)

1. Egg-laying
2. Flying
3. Toothless
4. Marsupials (pouched)
5. Carnivores
6. Insectivores
7. Rodents
8. Ungulates (hoofed)
9. Trunk-nosed
10. Marine
11. Primates

1. Egg-laying (duck-billed platypus, spiny echidnea)
2. Flying (bat)
3. Toothless (armadillo, anteater, sloth)
4. Marsupials (kangaroo, koala, opossum, wallaby)
5. Carnivores (dog, cat, bear)
6. Insectivores (mole, shrew, hedgehog)
7. Rodents (mouse, rat, squirrel, chipmunk, beaver, prairie dog)
8. Ungulates (cow, sheep, goat, pig, camel, giraffe, deer)
9. Trunk-nosed (elephant)
10. Marine (whale, dolphin, manatee)
11. Primates (monkey, ape, lemur, gorilla)