1. DIVERSITY OF MAMMALS Chapter 30.2
OBJECTIVES:
1. State the various characteristics of mammals in each of three subgroups.
2. Describe various adaptations that contribute to the diversity of mammals.

2. Mammal Classification
● the Class Mammalia is divided into three subgroups based on reproductive methods
1. Monotremes: mammals that reproduce by laying eggs
(duck-billed platypus and echidna - live only in Australia, Tasmania and New Guinea)

3. ● unique features of monotremes include reptilian bone structure in shoulder area, lower body temp than most mammals, a mix of chromosome size (normal, mammal and reptile-small)

4. marsupials: pouched animals with a short gestation period
● immediately following birth, the offspring crawl into a pouch (skin and hair) on the outside of the mother’s body (as early as 8d post fertilization) and continue to develop and be nourished with milk from mammary glands

5. ● marsupials typically live in Australia (and nearby islands) – the opossum is the only marsupial in N America

6. placental mammals: have a placenta (organ that provides food and oxygen to and removes waste and carbon dioxide from the developing young) - give birth to young that do not require further development in a pouch…
placental mammals are represented by 18 different orders…

7. Order Insectivora (shrews, hedgehogs, moles)
 smallest mammals, pointed snouts, live underground, insect-eaters

8. Order Chiroptera (bats)
 nocturnal, use sonar, adapted for flight, fruit and insect-eaters

9. Order Primates (monkeys, apes, humans)
 binocular vision, large brains, most are tree-dwellers, opposable thumbs

10. Order Xenarthra (anteaters, sloths, armadillos)
 toothless or peg-like teeth, insect-eaters

11. Order Rodentia (beavers, rats, woodchucks, marmots, squirrels, hamsters and gerbils)
 sharp incisor teeth, plant-eaters

12. Order Logomorpha (rabbits, pikas, hares)
● back legs are longer than front, adapted to jumping, incisors continuously grow

13. Order Carnivora (dogs, cats, wolves, bears, seals, walruses, coyotes, skunks, otters, minks, weasles)
● teeth adapted to tear flesh, meat-eaters

14. Order Proboscidea (elephants)
● long trunks, incisors become long tusks, largest land animal

15. Order Sirenia (manatees and dugongs)
● slow moving, big heads, no hind limbs

16. Order Perissodactyla (horses, zebras, rhinoceroses)
● hoofed, odd number of toes, plant-eaters

17. Order Artiodactyla (deer, antelope, cattle, sheep, pigs, goats, hippopotamus)
● hoofed, even number of toes, plant-eaters that chew cud

18. Order Cetacea (whales, dolphins, porpoises)
● front limbs that are flippers, no hind limbs, nostril forms a blowhole