Chapter 43

The order *_____________*, the ___________, is the only order in the subclass Prototheria

*Monotremata* (MAHN-oh-truh MAHT-uh); monotremes

Cetaceans are totally aquatic but evolved from land-dwelling mammals. They breathe through modified nostrils called _________.

*blowholes*

Often, mammals that live in very cold climates have heavy coats of fur and, or thick layers of fat, called *________*.

*blubber*

In horses, zebras, rodents, rabbits, and elephants, microorganisms that live in the ___________ complete digestion of the food

*cecum (SEE-kuhm)*

Humans, apes, and Old World monkeys have a similar *_________*, or number and arrangement of teeth

*dental formula*

Orangutans, gorillas, chimpanzees, bonobos, and humans make up the *____________*.

*great apes*

What were the three groups that appeared by the middle of the Cretaceous?

*monotremes, marsupials, placental mammals*

Also, in placental animals, the developing fetus receives nourishment through a blood-rich structure called the _________

*placenta*

All other living anthropoid primates are *__________*, meaning they tend to walk on all four limbs

*quadrupedal*

members of rodentia are called ________

*rodents*

A *________*, or wall of tissue, completely separates the ventricles. It prevents oxygenated and deoxygenated blood from __________.

*septum*; mixing

One of these chambers is the *_________*. Another chamber, known as the *__________*, contains symbiotic microorganisms.

*true stomach* ; *rumen* (ROO-muhn)

Order *Xenarthra*: -what animals? -where do they live?

-anteaters, armadillos, sloths -southern North America, Central America, South America

Describe the pattern of development of the offspring for Marsupials

-embryos develop for short period within mother's uterus -then emerges from uterus & crawls into mother's pouch (skin-lines pocket on abdomen) -newborn attaches to a nipple to feed in mother's pouch -newborn's development & growth continues inside pouch for several months

Describe the pattern of development of the offspring for Monotremes

-female lays 1 or 2 large eggs encased in thin, leathery shells & incubates them -yolk nourishes developing embryo in egg -at hatching, monotreme is v small and only partially developed -mother protects & feeds it milk from her mammary glands until it is ready to survive on its own

Describe the pattern of development of the offspring for Placental Mammals

-give birth to well-developed young after long period of development inside uterus -During this period, placenta provides nourishment & oxygen to the developing offspring -placenta begins to form shortly after fertilization, when fertilized egg attaches to lining of uterus -extensions from the chorion, the outer membrane of the embryo, grow into the lining of the uterus -Blood vessels from the uterus surround these extensions -nutrients & oxygen diffuse from mother's blood into blood of the offspring -carbon dioxide & other wastes diffuse from offspring into mother's blood -after birth, infants feed on milk for several weeks/months

Describe the characteristics of the two echidna species

-live in dry woodlands, deserts -protective spines -long snout -sticky tongue to feed on ants/other insects -incubate eggs in a pouch on the belly

According to this multiregional hypothesis...

-local populations of H. erectus gave rise to local populations of H. sapiens all over the world. -interbreeding among populations was sufficient to keep all of humanity as a single species

Describe the characteristics of the duckbill platypus

-water resistant fur -webbed feet -flattened tail that aids in swimming -uses wide, flat, leathery bill to find worms, crayfish, other invertebrates in soft mud -female digs den in riverbank to lay eggs & curls around eggs for protection/warmth -babies lick milk from mammary glands on mother's abdomen

Name the 12 orders of Placental Animals

1) Xenarthra 2) Lagomorpha 3) Rodentia 4) Primates 5) Chiroptera 6) Insectivora 7) Carnivora 8) Artiodactyla 9) Perissodactyla 10) Cetacea 11) Sirenia 12) Proboscidea

Describe the first mechanism a mammal uses to breathe

1) inhale by using their rib-cage muscles to expand the thoracic cavity, the body cavity that holds the lungs. 2) Mammals inherited this breathing mechanism but use it mostly under conditions of strenuous activity

By the middle of the Cretaceous period, about __________ years ago, three different kinds of mammals had appeared. _________ mammals belong to one of these three groups.

100 million; Modern

A mammal's brain is about ____ times heavier than the brain of a similarly sized fish, amphibian, or reptile

15

So, dinosaurs coexisted with mammals for more than __________ years

150 million

In _____, Mary Leakey and colleagues at the National Museums of Kenya announced the finding of a new hominid species, Australopithecus anamensis, that predated A. afarensis (Lucy's species) by about 300,000 years.

1995

Elephants have long gestation periods. A calf takes _____ to _____ months to develop. Female elephants can continue to give birth until the age of _____, and elephants can live to be _____ years old

20; 22; 70; 80

Scientists think that the ancestors of all mammals appeared more than __________ years ago. Around that time, _______ seem to have split into two groups.

300 million; amniotes

The first humans classified as H. sapiens appeared in _______ about ___________ years ago

Africa; 160,000

An analysis of mitochondrial DNA from people around the world suggests that humans did arise in _________. It is possible that humans migrated out of ________ more than once

Africa; Africa

Rodents flourish on every continent except _________ and are adapted to a wide range of habitats

Antarctica

________ ancestors of the first hominids were probably also quadrupedal.

Apelike

Ungulates with an EVEN number of toes are in the order ___________. This order includes about 210 species of deer, cattle, giraffes, pigs, and camels.

Artiodactyla (AHRD-ee-oh-DAK-tuh-luh)

The only living species of this order are the ______ elephant and the _______ elephant, which is the largest living land mammal

Asian; African

The duckbill platypus is adapted to life around rivers or streams in ______

Australia

The majority of about 280 species of marsupials live in ________, but some live in _________ and the _________. The Virginia opossum is the only marsupial native to the __________.

Australia; New Guinea; Americas; United States

Why did monotremes branch off earlier in the history of mammals than other kinds of mammals did

Because today's monotremes possess some features characteristic of ancestral forms, such as egg laying

_________ is the distinguishing characteristic of Hominids

Bipedalism

The 274 living species of the order ___________ are distributed worldwide.

Carnivora (kahr-NIV-uh-ruh)

Closely related to Artiodactyla is the order ____________, members of which are called _________

Cetacea (see-TAY-shuh); cetaceans

The only mammals that truly fly, the bats, make up the order ____________

Chiroptera (kie-RAHP-tuh-ruh)

Describe the second mechanism a mammal uses to breathe

Contraction of the diaphragm enlarges the thorax and thus expands the thoracic cavity

The first discovery of H. sapiens fossils was in Cro-Magnon cave in France, so some members of H. sapiens are referred to as _________________

Cro-Magnons (KROH-man-YAWNS)

Unlike most other reptiles, which have uniformly shaped teeth, a carnivorous synapsid of the genus ________ had specialized teeth—long ________ front teeth and smaller back teeth.

Dimetrodon; bladelike

The order xenarthra was once named _____________, meaning "__________," because many members of this order do not have prominent teeth.

Edentata (EE-den-TAH-duh); toothless

Name the 6 characteristics of all mammals

Endothermy, Hair, Completely divided heart, Milk, Single jawbone, Specialized teeth

Fossils of _________ are between 1.6 million and 2.5 million years old and have a brain capacity of 590 to 690 cm3

H. habilis

___________ include humans and extinct humanlike anthropoid species

Hominids

Later species, __________ (meaning "upright human"), had a brain capacity of 800 to 1,250 cm3, or about two-thirds that of a modern human. H. erectus had a ________ skull, larger brow ridges, a lower forehead, and larger, protruding ___ than modern humans have

Homo erectus; thicker; teeth

Sometime after the appearance of the australopithecines, new hominids appeared that are classified in the genus ______. Extinct and living members of this genus are called ___________.

Homo; humans

Where do scientists think that marsupials began to evolve

In isolation when Australia and New Guinea drifted away from the other continents more than 40 million years ago. At that time, placental mammals were rare in the Australian region; this allowed marsupials to radiate into habitats unoccupied by placental mammals.

The order ___________, members of which are called ________, includes about 70 species of rabbits, hares, and pikas

Lagomorpha (LAG-uh-MAWR fuh); lagomorphs

Look at figure 43-16

!

look at figure 43-18

!!

Paleontologists and anthropologists (scientists who study humans) have unearthed sufficient fossil evidence to conclude that a variety of humanlike species lived on Earth within the past ___________

10 million years

Three more-recent species, ________, _________, __________, date from about 2.6 million to 1 million years ago

A. aethiopicus, A. robustus, and A. boisei

According to the recent-African-origin hypothesis suggests that...

H. sapiens evolved from H. erectus uniquely in Africa about 100,000 to 200,000 years ago, then migrated out of Africa, and populated the globe

The order _________ includes about 390 species of shrews, hedgehogs, and moles living in North America, Africa, and Europe

Insectivora (in-sek-TIV-uh-ruh)

_______ is simple to digest, so most carnivores have short, simple digestive systems.

Meat

great ape

an ape whose face has little hair and whose hands have nails and complex fingerprints, such as an orangutan, gorilla, or chimpanzee

Word Roots and Origins: from the Latin sapere, meaning "to taste" or "to know"

sapiens

The ________ of the mammalian heart allows efficient pumping of blood throughout the body

structure

Many primate traits are adaptations for living in groups in ______. Examples include strong ___________ vision and *__________*, or hands, feet, and tails that can grasp

trees; three-dimensional; *prehensile appendages*

Modified incisors, called _____, efficiently dig up roots and strip bark from branches

tusks

Word Roots and Origins: from the Latin ungula, meaning "hoof"

ungulate

Johanson and colleagues gave the new fossil the species name Australopithecus afarensis and the nickname "_______"

Lucy

The marsupials had previously been classified in one order, _____________, but are now divided into at least seven orders within the _______ Marsupialia

Marsupialia (mahr-SOO-pee-AY-lee-uh); super order

____________, a distinctive type of human, lived in Europe and Asia from about 230,000 to 30,000 years ago.

Neanderthals

By the early _________ period (272 million to 298 million years ago), various large synapsids had appeared.

Permian

Some scientists once placed pinnipeds in their own order—__________

Pinnipedia

__________ carnivores, have a set of teeth specialized for gripping, holding, tearing, and crushing food. __________ carnivores are recognizable by their sharp incisors and long canines.

Predatory; Mammalian

The order ____________ is made up of 235 living species, including lemurs, tarsiers, lorises, monkeys, gibbons, apes, and humans.

Primates

Members of the order _________ have a nose that is modified into a long, boneless trunk, or proboscis

Proboscidea (PROH buh-SID-ee-uh)

Related to Lagomorpha is the order _________

Rodentia

The human spine curves in a(n) _____ shape that allows for upright posture

S

Four species of manatees and dugongs make up the order __________, commonly called the ________

Sirenia (sie-REE-nee-uh); sirenians

Marsupials were once common in _______ as well but were displaced by placental mammals that migrated in from the north.

South America

Both the first mammals and the first dinosaurs appeared during the _______ period

Triassic

Therapsids survived through the ______ period and into the _______ period.

Triassic; Jurassic

Biologists think that, based on fossil and molecular evidence, ________ evolved as a unique lineage in what is now South America

Xenarthra

diaphragm

a dome-shaped muscle that is attached to the lower ribs and that functions as the main muscle in respiration

mammary gland

a gland that is located in the chest of a female mammal and that secretes milk

ungulate

a hoofed mammal

molar

a large tooth that is located in the back of the mouth and that is used to grind and crush food

marsupial

a mammal that does not have a placenta and that carries and nourishes its young in a pouch

monotreme

a mammal that lays eggs

placental mammal

a mammal that nourishes its unborn offspring through a placenta inside its uterus

hominid

a member of the family Hominidae of the order Primates; characterized by bipedalism, relatively long lower limbs, and lack of a tail; examples include humans and their ancestors

human

a member of the genus Homo of the family Hominidae; includes modern humans and closely related extinct species

synapsid

a now extinct mammal-like reptile

cecum

a sac usually found at the beginning of the large intestine

canine

a sharp tooth located on either side of the jaw

Tubulidentata Description: nearly hairless insectivores with piglike bodies and long snouts; found in southern Africa Example: ______

aardvarks

Also, the body temperature of a mammal is often _______ that of its environment, so heat constantly escapes through the animal's _____ and _______.

above; skin; breath

Human toes are _______ with each other and are much shorter than ape toes. Because humans are the only primates that have this foot structure, the shape of the human foot is likely an adaptation for _________.

aligned; bipedalism

prehensile appendage

an appendage that can grasp objects, as in a primate's hand, foots, or tail

pinniped

an aquatic, fin-footed animal, such as a sea lion, walrus, or seal

australopithecine

an early hominid that may have lived more than 3.6 million years ago

viviparous

an organism whose offspring develop within the mother's body and are born alive

Word Roots and Origins: from the Greek anthropos, meaning "man," and eidos, meaning "shape"

anthropoid

The gibbon is one of the ________, a group that also includes New World monkeys, Old World monkeys, apes, and humans

anthropoid primates

incisor

any of the four cutting teeth located between the canines in the upper and lower jaws

The mammalian heart has two _____ and two ________ (so it has ________ chambers).

atria; ventricles; four

A number of fossil organisms similar to Lucy have been classified as species of the genus Australopithecus within the subfamily of ____________, which may include other genera

australopithecines (AW-struh-loh-PITH-uh-SEENZ)

Baleen whales, such as the blue whale, lack teeth. Instead, they have *______*, thin plates of ________ that hang from the skin of the upper jaw like a curtain.

baleen; keratin

Among living mammals, only we humans, Homo sapiens, have the trait of __________, the tendency to walk upright on two legs

bipedalism

The energy used to heat a mammal's body would be wasted without adaptations such as ___________

body insulation

The ________ human pelvis supports internal organs during upright walking

bowl-shaped

Their ______ capacity ranged from 450 to 600 cm3. Some scientists call these later hominids robust australopithecines, and some scientists place them in the genus Paranthropus instead of in the genus Australopithecus

brain

Compared to other primates, anthropoids have a more complex ________ and a larger ________- relative to body size.

brain structure; brain

Most members of this order (Carnivora) are called _________, which means "animals that eat meat."

carnivores

Perissodactyls have a _______

cecum

Word Roots and Origins: from the Latin intestinum caecum, meaning "blind intestine"

cecum

The *______* is a large sac that branches from the ______ intestine and acts as a fermentation chamber

cecum; small

Plants, however, can be difficult to digest because plants contain *_______*, a polymer of the sugar glucose.

cellulose

These differences are due mostly to the size of the ________, which is the outer region of the brain and the largest part of the brain in mammals.

cerebrum

For most mammals, the breakdown of food begins with ________. Other vertebrates simply _________ their food whole or in large pieces.

chewing; swallow

Like Lucy's species, this species was also similar to a ________ but probably bipedal. A possible descendant of Lucy's species was A. africanus, which lived about 2.3 to 3 million years ago

chimpanzee

One important fossil discovery was made in 1974 in the Afar Valley region of Africa by Donald Johanson and colleagues. The 3.2 million-year-old fossilized skeleton was of an anthropoid primate with the brain size of a _________. But the skeletal structure clearly showed that this organism was ________.

chimpanzee; bipedal

At the level of DNA sequence, a human is more closely related to a _________ than a chimpanzee is related to a _________. DNA and fossil evidence suggests that humans and chimpanzees share a common ancestor that lived about _________ years ago

chimpanzee; gorilla; 6 million

Humans, however, did not descend from ________. Rather, modern apes and humans both descended from an ancestral _______ species

chimpanzees; apelike

As hominid fossils are discovered and studied, scientists revise the __________ of some hominid species and debate hypotheses about the possible evolutionary relationship between these species. The ancestry of _________ is one such topic of debate.

classification; H. sapiens

Rather, several hominid forms arose, thrived, and became extinct over the past 7 million years. Furthermore, different species of hominids may have ________ in time and possibly interacted.

coexisted

Apes have similar areas of their brains that function in _________, and apes can learn to mimic certain forms of _____________

communication; human sign language

The ___________ septum is an adaptation that allows mammals' bodies to transport oxygen more efficiently.

complete

The similarities between whales and sirenians came about through __________ evolution

convergent

Primates have brains that have a relatively large _________, which make possible the complex behaviors characteristic of this group.

cortex

Teeth along the sides of the jaw ______, _______, or _______. By comparison, most reptiles' teeth are uniformly _____ and conelike throughout the mouth.

crush; grind; slice; sharp

Teeth: Chisellike *incisors* ______

cut

However, some tropical bats are active in the ____ and feed on ______ or flower nectar. These bats locate food by using their ______ and keen sense of ______. A few species of bats feed on meat or ________.

day; fruit; large eyes; smell; blood

oviparous

describes organisms that produce eggs that develop and hatch outside the body of the mother

Chewing speeds up __________ by breaking food into small pieces that provide a large surface area for attack by ___________

digestion; enzymes

Hiding by day and specializing on insects allowed the mammals to avoid threats from _________ or competition with them.

dinosaurs

Cetaceans include about 90 species of whales, _________, and porpoises worldwide

dolphins

The bat then analyzes the returning ________ to determine the size, distance, direction, and speed of the objects

echoes

Using a process called *_____________*, these bats emit high- frequency sound waves, which bounce off objects, including potential prey.

echolocation (EK-oh loh-KAY-shuhn)

Most other animals, such as insects and lizards, are ___________, animals that are heated or cooled by their surroundings. ___________ allows mammals to live in cold climates yet remain active

ectotherms; Endothermy

A mammal's respiratory system is adapted for _________ gas exchange. The lungs are large and contain millions of *________*, the small sacs in which gas exchange occurs.

efficient; alveoli

Macroscelidea Description: ground-dwelling insectivores with long, flexible snouts; 15 species found only in Africa Example: ________

elephant shrews

Although manatees and dugongs look like whales, they are more closely related to _________.

elephants

Animals do not produce ________ that can break down cellulose.

enzymes

The reason for their ________ is an ongoing scientific question. This species had once been classified as a subspecies of _________ but is now mainly classified as H. neanderthalensis. Neanderthals may have interacted with H. sapiens in some places.

extinction; Homo sapiens

Most bats have small _____ and large _____ and navigate by __________. Most bats are active at night and feed on insects.

eyes; ears; echolocation

The larger brain and smaller jaw in modern humans result in a __________ than that found in apes

flatter face

Cetaceans have fish-shaped bodies with forelimbs modified as ________. They lack hind limbs and have broad, flat tails that help propel them through the water.

flippers

Dermoptera Description: only two species exist; glide in air using a thin membrane stretched between their limbs; found only in parts of Asia Example: colugos or ________

flying lemurs

For example, a family of mammals called colugos, which are commonly called ________, was once placed in Insectivora. This family is now usually classified as another order, Dermoptera.

flying lemurs

Two main groups of ungulates are characterized by their ________ and by the presence of either a _____ or a _______

foot structure; rumen; cecum

Most primates have __________ eyes, a feature that enables depth perception. Many primates are active at ______ and have large eyes adapted for __________.

forward-facing; night; night vision

Mammals have a __________ heart whose two ________ are completely separated by a muscular wall. This division keeps _________ blood from mixing with ___________ blood and allows efficient pumping of blood through the circulatory system

four-chambered; ventricles; deoxygenated; oxygenated

With their powerful _____ _____ and large, ______ ______, anteaters rip open anthills and termite nests

front paws; sharp claws

Mammals have various types of teeth modified for different _________. Teeth at the _______ of the jaw bite, cut, or hold prey.

functions; front

All primates have __________ hands and, with the exception of humans, grasping _______.

grasping; feet

Teeth: *Molars* _______, ______, or ________

grind, crush, or cut

Teeth: Pointed *canines* ________, _______, and _______

grip, puncture, and tear

This change opened up many new _______ and _________ to mammals. So, mammals took over many of the _________ roles that dinosaurs previously had. Today, nearly all large terrestrial animals are _________.

habitats; resources; ecological; mammals

Evidence suggests that some early therapsids were endothermic and may have had ______.

hair

Adult cetaceans lack ______ except for a few bristles on the snout. A thick layer of blubber below the skin provides ________. Cetaceans use _________ to navigate, communicate, and find prey.

hair; insulation; echolocation

Most mammals are covered with a thick coat of hair, which insulates the body against _______. Hair is made of filaments of the protein ________.

heat loss; keratin

The physical characteristics of these later species suggest that they were a different lineage from A. afarensis. For example, they had _________ skulls, larger molars, and generally thicker bodies than Lucy's species did

heavier

They had _______ bones, thick brows, protruding jaws, and brains of about the same size as the brains of modern humans. They lived in caves and made stone scraper tools.

heavy

Sloths, on the other hand, are _________; their continuously growing teeth are adapted to ________ plants.

herbivores; grinding

Most artiodactyls are _________, although pigs are omnivores. Their molars are usually large and flat, for grinding plant material. Most artiodactyls are _______, or animals that have a rumen.

herbivores; ruminants

The teeth of lagomorphs continue to grow throughout their lifetime. Such teeth are an adaptation to a __________ diet

herbivorous

A mammal's body temperature stays _____ and nearly _____ because of adjustments in _________ and regulation of _______ through the body surface. This manner of controlling body temperature is called _________.

high; constant; metabolic rate; heat loss; endothermy

Some people speak of primates as the "_________" mammalian order. However, no species alive today is "________" than any other species alive today

highest; higher

In the early 1960s, scientists in East Africa found a __________ skull whose brain capacity was much larger than the brain capacity of Lucy's species but whose body was not much taller than Lucy's body

hominid

Of all animals, ______ have one of the highest ratios of brain size to body size. Whales, ______, and some primates also have high ratios

humans; dolphins

Hyracoidea Description: small rabbitlike herbivores; 7 species found mostly in Africa Example: _______

hyrax

endothermy

in animals, the characteristic of maintaining a high, constant body temperature through regulation of metabolism and heat loss

bipedalism

in hominids, the condition of being adapted to walk primarily upright on two legs

opposable thumb

in primates, a thumb that can touch and move in opposition to the other fingers of the hand

The sharp ________ are an adaptation to gnaw on seeds, twigs, roots, and bark. As a rodent gnaws, the _________ of the tooth wears away faster than the front surface, maintaining the tooth's edge.

incisors; back surface

Each half of the upper and lower mouth includes two _______, one ________, two _________, and three ________

incisors; canine; premolars; molars

Recall that in the hearts of lizards and turtles, an __________ septum allows the oxygen-rich blood and oxygen-poor blood to mix when the animal is inactive.

incomplete

Most members of this order are __________, which means "animals that eat insects." However, not all of them are members of the order Insectivora. Furthermore, some Insectivora eat ______.

insectivores; meat

Also, ___________ among populations around the world would have been possible during and after these migrations

interbreeding

Mammalian fossils are often identified by the __________.

jawbone

Pinnipeds, are generally ______ than land carnivores, and their _____ size helps them maintain body temperature

larger; large

Rodentia is the _______ mammalian order, which includes more than 1,800 species, or about 40 percent of all placental mammals

largest

The primate lineages that evolved the earliest include _______, ________, and ________. These groups are sometimes referred to as ________.

lemurs; lorises; tarsiers; prosimians

Rodents tend to produce many young in each _______. Squirrels, marmots, chipmunks, gophers, muskrats, mice, and rats are rodents. The porcupine is also a rodent.

litter

The first synapsids were small and looked like modern _______

lizards

Scientists disagree about whether to include certain families of ________ in the order Insectivora

mammals

In all living mammals, milk from the mother's _________ nourishes newborns. However, the pattern of ________ of the offspring differs from group to group.

mammary glands; development

Similarities in the _________ tissues of several kinds of mammals suggest that milk production had evolved by the end of the ________.

mammary; Triassic

Mammals breathe using two _________: one they share with some _______ and one that is unique

mechanisms; reptiles

Mammals, like birds, regulate body heat internally through ________ and externally through ________

metabolism; insulation

All animals produce heat internally when they __________, or produce energy from food. Mammals are *__________*, meaning they conserve and regulate this body heat

metabolize; *endotherms*

Early mammals were about the size of _______. Fossil skulls with large _________ suggest that these mammals were active at ______. Also, their teeth were adapted for feeding on ________.

mice; eye sockets; night; insects

Long digestive tracts of herbivorous mammals, such as the zebra, contain ____________ that can break down cellulose.

microorganisms

Moreover, the type of metabolism needed for endothermy also provides energy to perform strenuous activities for extended periods, such as ________________.

migrating long distances

Female mammals produce _____ to feed their offspring. Milk is a nutritious fluid that contains _____, ________, and ______. Milk is produced by ______________, which are modified sweat glands located on the thorax or abdomen.

milk; fats; protein; sugars; mammary glands

Other fossils are known from several continents. The earliest members of H. sapiens differed only slightly from _________ humans. Their average brain and body size were ____________ as modern human's.

modern; about the same

A bat's wing is a ___________ with a membrane of skin that stretches between extremely long finger bones to the hind limb

modified front limb

A rodent's teeth consist of a few _____ or _________ and two pairs of incisors that continue to grow as long as the rodent lives.

molars; premolars

Mammals are commonly classified into a single order of ________, 7 orders of ________, and about 18 orders of _________

monotremes; marsupials; placental mammals

In contrast, the largest primate, the ________, lives on the ground in dense African mountain forests

mountain gorilla

As a baleen whale swims, it gulps water, then closes its _______, and pushes the water out through the ________. Shrimp and other invertebrates get trapped behind the baleen and then are __________.

mouth; baleen; swallowed

Many scientists think that some sort of _______ _______ changed Earth's climate and forced the dinosaurs into extinction about 65 million years ago, at the end of the _________ period

natural disaster; Cretaceous

Most primates are __________ and have teeth suited for a varied diet

omnivores

anthropoid primate

one of a subgroup of primates that includes monkeys, apes, and humans

premolar

one of the eight teeth that are located between the molars and the canines

Nonhuman anthropoids also have grasping feet with an _________________

opposable big toe

Anthropoid adaptations include rotating shoulder and elbow joints and an __________, which can touch the other fingers

opposable thumb

Mammalian ____________ are uniquely adapted for endothermy

organ systems

The cerebrum evaluates input from the sense _______, ________ __________, initiates and regulates __________, and functions in memory and __________

organs; controls movement; behavior; learning

The first group is made up of monotremes. They are __________, meaning that they lay eggs.

oviparous

Because of its faster metabolism, a mammal uses more _______ and _______ than does a reptile of the same size. So, mammals have unique _________ and _______ systems.

oxygen; food; circulatory; digestive

Anthropoids can hold and manipulate objects precisely, as when a chimpanzee _______ or when a student ________

peels a banana; holds a pencil

Ungulates with an odd number of toes are _________, in the order _______

perissodactyls; Perissodactyla (PUH-ris-oh-DAK-tuh-luh)

The _________ characteristics of these later species suggest that they were a different lineage from A. afarensis

physical

Many fossil humans have ________ structures that are transitions between those of __________ and of modern humans

physical; australopithecines

Aquatic carnivores, known as _________, include the sea lions, seals, and walruses.

pinnipeds

Word Roots and Origins: from the Greek plakos, meaning "flat object" or "flat cake"

placenta

Nearly 95 percent of all mammalian species are __________, making up the infraclass ______ of the subclass _______

placental mammals; Eutheria; Theria

To sustain such a large body, an elephant feeds on _______ for up to 18 hours a day

plants

Just three species of monotremes exist today: the ______ and two ______ species

platypus; echidna

Among other unique structures, the human brain has extensive areas that function in the _______ and ________ of speech

production; understanding

The smallest known primate, the ________________, weighs only about 30 g and was discovered in _______ in Madagascar, where it lives mostly in trees

pygmy mouse lemur; 2000

The material is partly digested in the rumen, then _______, ________ again, and _________ again.

regurgitated; chewed; swallowed

The third group is made up of placental mammals. They are also viviparous, but in this group, the fetus typically develops within the mother's __________ ____________ for a longer time than it does in marsupials.

reproductive system

Plant material that has been chewed and swallowed enters the _______, where microorganisms begin to break the ________ into smaller molecules that can be absorbed into the animal's ____________.

rumen; cellulose; bloodstream

The animal may regurgitate and swallow the same food several times. Mammals that have a rumen are called *_________* and include cows, sheep, goats, giraffes, and deer.

ruminants

Pholidota Description: insectivores with protective scales composed of fused hair; resemble reptiles; found in Africa and southern Asia Example: pangolins or __________

scaly anteaters

Some individuals were as tall as modern humans. Because H. erectus fossils have been found on ___________ continents, scientists think that this hominid was the first to travel out of Africa. Charred animal bones indicate that H. erectus hunted and cooked its food

several

Teeth: *Premolars* ______, ______, _______ or ______

shear, shred, cut, or grind

Although the exact classification of some fossils is strongly debated, it is clear that human evolution did not proceed as a ________ lineage of increasingly humanlike forms

single

A mammal's lower jaw is made up of a _______ bone. By comparison, a reptile's lower jaw is made up of ________ bones.

single; several

Variations in the _____ and _______ of teeth among different mammalian species reflect differences in diet.

size; shape

Dogs, cats, raccoons, bears, hyenas, otters, seals, and sea lions are some wellknown carnivores. Most are _______ hunters with strong senses of _____ and _______.

skilled; sight; smell

Paleontologists recognize early synapsids by the structure of their _______, which has a single opening in a bone just behind the _________. This same type of skull is found in all later synapsids, including _________, although often in a modified form.

skull; eye socket; mammals

Armadillos supplement their insect diet with _______, ______, _______, and scavenged _______

small reptiles, frogs, mollusks; meat

The Insectivora are usually _______ animals with a high _________ rate. Most have long, _______ noses that enable them to probe in the soil for insects, worms, and other _______. Their ________ teeth are adapted for grasping and piercing prey.

small; metabolic; pointed; invertebrates; sharp

The importance of each sense depends on the mammal's environment. For example, most bats, which are active at night, rely largely on ________- rather than vision for navigating and finding food

sound

In some herbivorous mammals, the structure that is called a *_________* is actually made up of four _________.

stomach; chambers

Food passes through the _______ and __________ before entering the cecum. Mammals with a cecum do not chew _____.

stomach; small intestine; cud

Importantly, the new fossils were found along with _______ tools. Scientists named the new species __________, the "handy human"

stone; Homo habilis

The name xenarthra means "_________" and refers to the unique structure of the lumbar vertebrae of members of this order

strange joints

Other adaptations of carnivores include _______, long ________ teeth, and clawed _______ to seize and hold prey. Many terrestrial carnivores have skeletal adaptations, such as long limbs, to run quickly

strong jaws; canine; toes

As a result of alveoli, mammalian lungs have a much larger ________ available for gas exchange than reptilian lungs do.

surface area

The cerebrum's surface is usually folded and fissured, which greatly increases its _________ without increasing its ________

surface area; volume

Pinnipeds are efficient at _________, with streamlined bodies and four limbs adapted as ________. Although pinnipeds spend much of their time in the _____ feeding, they return to _______ to sleep and to give birth.

swimming; flippers; sea; land

Their front limbs are flippers modified for _________. Like whales (order Cetacea), sirenians lack ______ limbs and have a flattened tail for propulsion.

swimming; hind

One group gave rise to dinosaurs, birds, and modern reptiles. The other group, known as _______, gave rise to mammals and their extinct relatives.

synapsids

Some primates also have a grasping _______. Many primates live in _______, where grasping feet, hands, and tails are essential adaptations. In humans, grasping ______ serve many purposes.

tail; trees; hands

Anteaters completely lack ______. Armadillos and sloths have ________ teeth that lack _______. Most edentates feed on _______, which they capture with a long, ________ tongue

teeth; peglike; enamel; insects; sticky

A wide range of body sizes and adaptations allow primates to live in a variety of ________

terrains

Dinosaurs dominated most _______ habitats while populations of small mammals continued to evolve.

terrestrial

Therapsids were the most abundant __________ during the late ________ period.

terrestrial vertebrates; Permian

therapsid

the extinct order of mammal-like reptiles that likely gave rise to mammals

rumen

the first of the four compartments in the stomach of a ruminant mammal

baleen

the horny plates that hang from the mouth of some whales; used to filter out water but to retain solids when whales feed

echolocation

the process of using reflected sound waves to find objects; used by animals such as bats

A subset of synapsids, called _________, appeared later in the Permian period and gave rise to mammals

therapsids

Several features we associate with mammals evolved first among early ________. For example, like the limbs of many early therapsids, mammals' _____ are directly beneath the body.

therapsids; limbs

A rich fossil record of transitional forms between _________ and __________ exists. By studying these fossils, scientists can trace the _______ changes that occurred during this transition and infer additional _______, ecological, and ________ changes.

therapsids; mammals; anatomical; physiological; behavioral

The bat's clawed ___________ sticks out from the top edge of the wing. Bats use their _______ for walking, climbing, and grasping

thumb; thumbs

Two subgroups of cetaceans are the _______ whales and _______ whales

toothed; baleen

Scandentia Description: squirrel-like omnivores that live on ground and in trees; feed on fruit and small animals; found in tropical Asia Example: ________

tree shrews

Mammals with hoofs are _______

ungulates (UHNG-yoo-lits).

Lagomorphs differ from rodents in that they have a double row of ________, with two large ________ backed by two smaller ones

upper incisors; front teeth

As with other terrestrial vertebrates, a mammal's survival depends on five major senses:

vision, hearing, smell, touch, and taste

The second group is made up of marsupials. They are ________, which means that they give birth to live young. In marsupials, the young develop within a _______ on the mother's body for some time after birth.

viviparous; pouch

Apes living in the ______, however, do not use the complexity of signals found in human language

wild