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

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Presentation on theme: "Chapter 32-2:Diversity of Mammals Chris Dinh Yonathan Andu Andrew Carpenter."— Presentation transcript:

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  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) Orders of Placental Mammals

7  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) Orders cont.

8  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 Biogeography of Mammals

9  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 Quiz


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