1. Class Mammalia

2. General Characteristics
Bilaterally symmetrical
Hair
Mammary glands (produces milk)
Nurse young
Endothermic (warm blooded)
Unique inner ear – Incus, Malleus, Stapes
Dioecious - Internal fertilization
Diphyodonty – Two teeth (replace teeth once)
Lower Jaw – Made of one bone attached directly to head (improved power)

3. Heterodont dentition
Specialized teeth with different function
Birth to live young
Produce a placenta (usually) – nourishing fetus (similar to yolk sac in reptiles/birds)

4. Mammalian Orders 6 Major Orders: 1.) Order Rodentia
2.) Order Artiodactyla
3.) Order Carnivora
4.) Order Cetacea
5.) Order Primates
6.) Order Monotremata

5. Order Rodentia Rodents!
Mice, squirrels, gophers, beavers, & guinea pigs
Many have been pests
Have continuously growing incisors
Incisors = front teeth
Must gnaw to keep short

6. Have a short breeding cycle
Largest group of mammals

7. Order Artiodactyla Pigs, hippos, camels, deer, sheep, etc. 220 species
Means “even-toed” – they lost the first (many have shortened the 2nd and 5th

8. Mostly obligate herbivorous/grazing animals Suinae (hogs/pigs)
Are omnivorous – eat both

9. Order Carnivora
Meat eaters!
Canines, cats, bears, raccoons, seals, otters, walruses, etc.
260 species
Are predatory

10. Enhanced vision and hearing
Have special teeth and/or claws to take down prey

11. Order Cetacea
Whales and dolphins
Have blubber for insulation
Up and down movement of tail (unlike side to side by fish)
All aquatic
Highly intelligent

12. Use sonar to locate food

13. Order Primates
Gorillas, chimps, orangutans, humans, monkeys, lemurs
Bipedal – stand on two feet
Adaptations for tree-living
Strong limbs with opposable digits

14. Generally largest brain:body ratio
Small ants & small birds
Extensive parental care

15. Order Monotremata Duck Billed Platypus and Echidnas (spiny anteater)
Only mammals to lay eggs
Have a single opening called a cloaca for urination, defecation, and reproductive
Platypus has a poisonous barb on the back foot

16. Order Monotremata
Poison Barb
Echindas