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
