Chapter 43Mammals

Section 3

Diversity of Mammals

Mammalian Orders• Mammals are classified into a

single order of monotremes, 7 orders of marsupials, & about 18 orders of placental mammals

Monotremes• Order Monotremata

• Egg-laying mammals

• Duckbill platypus- Australia- water resistent fur, webbed feet & flattened tail

• Spiny anteater- Australia- feed on ants & insects- sticky tongue

Marsupials• Order Marsupialia

• Majority live in Australia, and some live in New Guinea

• Virginia opossum- only marsupial in USA

• Have pouch to raise young in

Placental Mammals• Nearly 95% of all mammalian

species are placental mammals

Order Xenarthra• Anteaters, armadillos, & sloths

• Location: N. America, C. America, & S. America

• Xenarthra- “strange joints”

• Feed on insects or plants

Order Lagomorpha• Rabbits, hares, & pikas

• Double row of upper incisors, with two large front teeth backed by two smaller ones

• Teeth grow throughout lifetime & adapted to herbivorous diet

Order Rodentia• Rodents: squirrels, marmots,

chipmunks, gophers, muskrats, porcupines, mice, & rats

• Rodent’s teeth consist of a few molars or premolars and two pairs of incisors that grow all of the rodent’s life

Order Primates• Lemurs, tarsiers, monkeys,

gibbons, apes, & humans

• Omnivores; large brains

• Forward-facing eyes for depth perception

• Grasping hands, feet, and tails

Order Chiroptera• Mammals that truly fly- bats• Wing- modified front limb with a

membrane of skin that stretches between digits

• Use thumbs for walking, climbing, & grasping

• Small eyes & large ears for echolocation- active at night

Order Insectivora• Shrews, hedgehogs, & moles• N. America, Africa, & Europe• Most have long, pointed noses that

help them probe the soil for insects• Have sharp teeth to grasp & pierce

prey

Order Carnivora• Animals that eat meat- carnivores• Dogs, cats, raccoons, bears,

hyenas, otters, seals, & sea lions• Strong sense of smell and sight• Strong jaws, large teeth, clawed toes• Aquatic carnivores- pinnipeds- sea

lions, seals, walruses

Order Artiodactyla• Hoofed animals- ungulates

• Ungulates with even number of toes- artiodactyls- deer, cattle, giraffes, pigs, and camels

• Herbivores- most have rumen

• Molars are flat and large for grinding plants

Order Perissodactyla• Ungulates with an odd number of

toes- perissodactyls

• Horses, zebras, rhinoceros, & tapirs

• Location: Africa & Asia

• Have a cecum

Order Cetacea• Whales, dolphins, porpoises• Lack hind-limbs, have tails• Totally aquatic, but evolved from land • Breathe through modified nostrils-

blowhole• Use echolocation to locate prey,

navigate, & communicate• Toothed whales- dolphins, orcas,

sperm whale

Order Sirenia• Manatees and dugongs

• Herbivores

• Location: tropical seas, estuaries, and rivers

• Closely related to elephants- evolutionary speaking

Order Proboscidea• Asian and African Elephant• Largest living land mammal• African elephant- 13,200 lbs• Feed on plants for 18 hours each

day• Nose is modified into trunk for

grasping “proboscis”

Other Orders• The 12 orders just described

include most of the familiar placental mammals.

• The 6 remaining orders contain just 1% of the mammalian species.

REVIEW!!!• Which continent is a natural home

of both monotremes and marsupials?

• Compare manatees to toothed whales.