1. Chapter 32-2:Diversity of Mammals
Chris Dinh
Yonathan Andu
Andrew Carpenter

2. Mammalia The class Mammalia contains about 4500 species Very diverse
3 groups of living mammals: Monotremes, marsupials, and placentals
Groups differ in means of reproduction and development

3. Monotremes “Monotreme” means single opening
Share two notable characteristics with reptiles: lay eggs and have cloaca
Lay soft-shelled eggs that are incubated outside of mother
Eggs hatch in about ten days
Young are nourished by mothers milk
Only three species of Monotremes exist today

4. Marsupials
Marsupials- mammals bearing young that usually complete their development in an external pouch
Embryo are born at a very early stage of development
Attatch to a nipple found inside a pouch called a marsupium, found in most marsupial species
Young spend several months on the nipple until they are ready to survive on their own
Include kangaroos, koalas, and wombats

5. Placentals The kind we are most familiar with! Cats, dogs, lions, etc.
Group gets name from an internal structure called the placenta-formed when the embryo’s tissue joins with the tissue from within its mothers body
In placental mammals, nutrients, oxygen, carbon dioxide, and wastes are exchanged between the embryo and mother with the placenta
This allows embryos to develop longer

6. Orders of Placental Mammals
There are 12 orders of placental mammals:
Insectivores- insect eaters that have long narrow snouts and sharp claws well suited for digging (shrews, hedgehogs)
Sirenians- herbivores that live in rivers, bays, and warm coastal waters scattered throughout most of the world (manatee)
Cetaceans- adapted to underwater life yet must come to the surface to breathe (whales, dolphins)
Chiropterans- winged mammals, the only mammals capable of flight (bats)
Rodents- single pair of long, curved incisor teeth in both upper and lower jaw, used for gnawing wood and other hard plant material (rats, squirrels)
Perissodactyls- hoofed animals with an odd number of toes on each foot (horses, tapirs, zebras)

7. Orders cont.
Carnivores- stalk or chase their prey by running or pouncing, then kill the prey with sharp teeth (dogs, bears)
Artiodactyls- hoofed mammals that have even number of toes on each foot, mostly consists of large grazing animals (giraffes, camels)
Lagomorphs- herbivores that have two pairs of incisors, one pair on both jaws, and have hind legs adapted for leaping (rabbits)
Xenarthrans- have simple teeth without enamel, some with no teeth at all (sloth, armadillo)
Primates- have highly developed cerebrum and complex behaviors (lemurs, apes)
Proboschideans- Mammals with trunks (elephant)

8. Biogeography of Mammals
Earth’s geography helped shape mammals
During Paleozeic Era, the continent was one large landmass where mammals could roam freely
Overtime, after the land separated, unique mammal groups did too
Similar ecological opportunities on the different continents have produced some striking examples of convergent evolution in mammals

9. Quiz Q: About how many species of mammals are their? A: 4500 species
Q:What are the three groups of mammals?
A: Monotremes, Marsupials, and Placentals
Q: How many orders of Placentals are there?
A: 12