End Show Slide 1 of 25 Copyright Pearson Prentice Hall Biology

End Show Slide 2 of 25 Copyright Pearson Prentice Hall 32-2 Diversity of Mammals

End Show 32-2 Diversity of Mammals Slide 3 of 25 Copyright Pearson Prentice Hall Diversity of Mammals The class Mammalia contains about 4500 species. Tooth structure and the number and kind of bones in the head are used to classify mammals. The most important way to categorize living mammals is by the way they reproduce and develop.

End Show 32-2 Diversity of Mammals Slide 4 of 25 Copyright Pearson Prentice Hall Diversity of Mammals The three groups of living mammals are: monotremes marsupials placentals

End Show 32-2 Diversity of Mammals Slide 5 of 25 Copyright Pearson Prentice Hall Monotremes and Marsupials How do the three groups of living mammals differ from one another?

End Show 32-2 Diversity of Mammals Slide 6 of 25 Copyright Pearson Prentice Hall Monotremes and Marsupials Monotremes Monotremes lay eggs. Monotremes share two notable characteristics with reptiles: The digestive, reproductive, and urinary systems all open into a cloaca. Females lay soft-shelled eggs that incubate outside the body.

End Show 32-2 Diversity of Mammals Slide 7 of 25 Copyright Pearson Prentice Hall Monotremes and Marsupials Young monotremes are nourished by their mother's milk, which they lick from pores on her abdomen. Only three species of monotremes exist today: the duckbill platypus and two species of spiny anteaters, or echidnas. These animals are found in Australia and New Guinea.

End Show 32-2 Diversity of Mammals Slide 8 of 25 Copyright Pearson Prentice Hall Monotremes and Marsupials Marsupials Marsupials bear live young, but at a very early stage of development. Young marsupials complete their development in an external pouch. When marsupials reproduce, the fertilized egg develops into an embryo inside the mother's reproductive tract.

End Show 32-2 Diversity of Mammals Slide 9 of 25 Copyright Pearson Prentice Hall Monotremes and Marsupials Once born, the embryo crawls across its mother's fur and attaches to a nipple. Nipples are located in a pouch called the marsupium on the outside of the mother's body. The embryo spends several months attached to the nipple. The young marsupial will drink milk until it grows enough to survive on its own.

End Show 32-2 Diversity of Mammals Slide 10 of 25 Copyright Pearson Prentice Hall Placental Mammals Placental mammals are named for an internal structure called the placenta, which forms when the embryo's tissues join with tissues from within the mother's body.

End Show 32-2 Diversity of Mammals Slide 11 of 25 Copyright Pearson Prentice Hall Placental Mammals In placental mammals, nutrients, oxygen, carbon dioxide, and wastes are exchanged efficiently between embryo and mother through the placenta. The placenta allows the embryo to develop for a longer time inside the mother. Most placental mammals care for and nurse their young after birth.

End Show 32-2 Diversity of Mammals Slide 12 of 25 Copyright Pearson Prentice Hall Placental Mammals There are twelve orders of placental mammals. Insectivores (insect eaters with long, narrow snouts and sharp claws) Sirenians (large, slow moving mammals that live in aquatic environments) Cetaceans (aquatic mammals that must come to the surface to breathe) Rodents (have a single pair of long, curved incisor teeth)

End Show 32-2 Diversity of Mammals Slide 13 of 25 Copyright Pearson Prentice Hall Placental Mammals Perissodactyls (hoofed mammals with an odd number of toes on each foot) Artiodactyls (hoofed mammals with an even number of toes on each foot) Lagomorphs (herbivores with two pairs of incisors and hind legs adapted for jumping) Carnivores (have sharp claws and teeth that they use to catch, kill, and eat prey)

End Show 32-2 Diversity of Mammals Slide 14 of 25 Copyright Pearson Prentice Hall Placental Mammals Chiropterans (winged mammals) Xenarthrans (simple teeth without enamel, or no teeth) Primates (highly developed cerebrum and complex behaviors) Proboscideans (mammals with trunks)

End Show 32-2 Diversity of Mammals Slide 15 of 25 Copyright Pearson Prentice Hall Biogeography of Mammals How did convergent evolution cause mammals on different continents to be similar in form and function?

End Show 32-2 Diversity of Mammals Slide 16 of 25 Copyright Pearson Prentice Hall Biogeography of Mammals Earth’s geography has shaped today’s mammals.

End Show 32-2 Diversity of Mammals Slide 17 of 25 Copyright Pearson Prentice Hall Biogeography of Mammals During the Paleozoic Era, the continents were one large landmass, and mammals could migrate freely across it. As continents drifted apart during the Mesozoic and Cenozoic, ancestors of mammal groups were isolated from one another. Each landmass took with it a unique array of mammal groups.

End Show 32-2 Diversity of Mammals Slide 18 of 25 Copyright Pearson Prentice Hall Biogeography of Mammals Similar ecological opportunities on the different continents have produced some striking examples of convergent evolution in mammals. Landmasses merged in the late Cenozoic, and mammals dispersed into new habitats. Living mammals reflect the diversity that resulted.

End Show 32-2 Diversity of Mammals Slide 19 of 25 Copyright Pearson Prentice Hall Biogeography of Mammals Convergent Evolution in Mammals Giant Anteater Aardvark Common Echidna Chinese Pangolin Nine-Banded Armadillo

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End Show Slide 21 of 25 Copyright Pearson Prentice Hall 32-2 Most mammals are a.monotremes. b.marsupials. c.placental mammals. d.placental marsupials.

End Show Slide 22 of 25 Copyright Pearson Prentice Hall 32-2 Monotremes are the only group of mammals that a.lay eggs b.have hair. c.feed their young with milk. d.are endotherms.

End Show Slide 23 of 25 Copyright Pearson Prentice Hall 32-2 Rabbits belong to an order of mammals called the a.cetaceans. b.lagomorphs. c.proboscideans. d.chiroptera.

End Show Slide 24 of 25 Copyright Pearson Prentice Hall 32-2 Ant-eating mammals on different continents look similar to each other because they are all a.a result of divergent evolution. b.adapted to similar ecological opportunities. c.recently evolved from a common ancestor. d.evolved from an ant-eating reptile.

End Show Slide 25 of 25 Copyright Pearson Prentice Hall 32-2 What is the function of the placenta? a.production of milk b.exchange of materials between fetus and mother c.digestion of food d.protection of a young mammal after birth

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