2. Evolution: from reptiles (a branch called therapsids) ~ 150 mya What event (65 mya) provided mammals a “window of opportunity”?

4. Common Features of Mammals: 1. Complex Brain – allows complex behavior, learning, curiosity.

5. 2. Well Developed Heart – Four Chambered Heart Warm Blooded (Endothermy)

6. 3. Well Developed Lungs – Air intake aided by what muscle?

7. 4. Skin Glands a.Mammary Glands – milk (lactose)

8. b. Sweat Glands Regulate body temperature & get rid of wastes Humans – all over Dogs & Cats - paws

9. C. Sebaceous (Oil) Glands Lubricate hair & skin

10. d. Scent Glands communication

11. 5. Hair traps air therefore insulates This is a distinctly mammalian trait. Hair may also function for camouflage or signaling. Aquatic mammals have lost most of their hair (replaced with blubber)

13. 6. Diphyodont Teeth Two sets: Baby teeth & Adult teeth (humans 20, 32)

14. The two traits that make you a mammal?

16. Monotremes Oviparous – lay eggs

18. Marsupials Ovoviviparous – young develop inside mom (attached to yolk sac) Short gestation Further development in pouch (nipples-milk)

19. Examples of Marsupials:

20. Placental Mammals 95% of all mammals Internal development (viviparous) Longer gestation Fetus-umbilical cord-placenta-uterine wall