CAMPBELL BIOLOGY: CONCEPTS & CONNECTIONS,

NINTH EDITION, GLOBAL EDITION

PowerPoint Lectures

Chapter 19
The Evolution of
Vertebrate Diversity TAYLOR
SIMON
DICKEY
HOGAN
REECE

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Lecture by Edward J. Zalisko
 Introduction
• Vertebrates have been evolving for half a billion
years.
• There are currently more than 60,000 vertebrate
species.
• Scientists are piecing together the evolutionary
history of vertebrates using clues from fossils,
genetics, morphology, and developmental
homologies among present-day animals.

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Figure 19.0_1

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Figure 19.0_2
Chapter 19: Big Ideas

Vertebrate Evolution Primate Diversity

and Diversity

Hominin Evolution
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 VERTEBRATE EVOLUTION
AND DIVERSITY

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 19.1 Shared derived characters define the
major clades of chordates
• Using a combination of anatomical, molecular, and
fossil evidence, biologists have developed
hypotheses for the evolution of chordate groups.
• Figure 19.1 illustrates a current view of the major
clades of chordates and lists some of the derived
characters that define the clades.

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Figure 19.1

Lancelets

Chordates
Common Tunicates
ancestor of
chordates
Hagfishes

Vertebrates
Lampreys

Sharks, rays

Jawed vertebrates
Vertebral
column
Ray-finned
Jaws fishes

Lobe-fins
Lungs or lung
derivatives
Amphibians

Tetrapods
Lobed fins

Reptiles

Amniotes
Legs

Amniotic egg Mammals

Milk

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 Checkpoint question List the hierarchy of clades to
which mammals belong.
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 19.2 Hagfishes and lampreys lack hinged
jaws
• Hagfishes and lampreys
• have rudimentary vertebrae,
• have a notochord for the body’s main support, and
• lack hinged jaws and paired fins.
• Hagfishes are deep-sea scavengers that produce
slime as an antipredator defense.
• Lamprey adults are parasites that penetrate the
sides of fishes with their rasping tongues.

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Figure 19.2a

Slime glands

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Figure 19.2b

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Figure 19.2b_1

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Figure 19.2b_2

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 19.3 Jawed vertebrates with gills and paired
fins include sharks, ray-finned fishes, and
lobe-finned fishes
• Jawed vertebrates
• appeared in the fossil record about 440 million
years ago and
• diversified, using their paired fins and tail to chase a
wide variety of prey.
• Jaws may have evolved by modifications of
skeletal supports of the anterior pharyngeal (gill)
slits.
• The remaining gill slits remained as sites of gas
exchange.
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Figure 19.3a
Gill Skeletal
slits rods Skull

Mouth

Hinged jaw
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 19.3 Jawed vertebrates with gills and paired
fins include sharks, ray-finned fishes, and
lobe-finned fishes
• Three lineages of jawed vertebrates with gills and
paired fins are commonly called fishes:
1. chondrichthyans, sharks and rays, have a
flexible skeleton made primarily of cartilage,
2. ray-finned fishes, for example, tuna, trout, and
goldfish, have a skeleton made of bone, and
3. lobe-finned fishes, coelacanths and lungfishes,
have a series of rod-shaped bones in their
muscular pectoral and pelvic fins.

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Figure 19.3b

Gill openings

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Figure 19.3c

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 Checkpoint question From what structure might
the swim bladder of ray-finned fishes have
evolved?
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Figure 19.3e

A seahorse

A balloon fish

A flounder
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Figure 19.3e_1

A balloon fish
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Figure 19.3e_2

A seahorse

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Figure 19.3e_3

A flounder

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Figure 19.3f

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 Video: Shark Eating a Seal

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 Video: Manta Ray

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 Video: Clownfish and Anemone

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 Video: Coral Reef

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 Video: Seahorse Camouflage

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 19.4 EVOLUTION CONNECTION: New fossil
discoveries are filling in the gaps of tetrapod
evolution
• During the late Devonian, a line of lobe-finned
fishes gave rise to tetrapods, jawed vertebrates
with limbs and feet that can support weight on
land.
• Adapting to life on land was a key event in
vertebrate history.
• All subsequent groups of vertebrates, amphibians,
mammals, and reptiles (including birds) are
descendants of these early land-dwellers.

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Figure 19.4a
Devonian Carboniferous Permian

Lungfishes

Eusthenopteron

Panderichthys

Tiktaalik

Acanthostega

Ichthyostega
Limbs with
digits

Tulerpeton

Amphibians
Key to limb bones
Humerus
Radius
Time known Amniotes
Ulna
to exist
Fin/Foot

415 400 385 370 355 340 325 310 295 280 265 0
Time (millions of years ago)
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 Checkpoint question How did Acanthostega
change scientists’ concept of tetrapod evolution?
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 19.5 Amphibians are tetrapods—vertebrates
with two pairs of limbs
• Amphibians
• include salamanders, frogs, and caecilians,
• use their moist skins to supplement their lungs for
gas exchange,
• often have poison glands in their skins,
• usually lay their eggs in water,
• undergo metamorphosis from a larval stage to the
adult form, and
• were the first tetrapods to colonize land.

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Figure 19.5a

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Figure 19.5b

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 Checkpoint question In what ways are amphibians
not completely adapted for terrestrial life?
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Figure 19.5d-e

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Figure 19.5d

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Figure 19.5e

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 19.6 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
• Reptiles (including birds) and mammals are
amniotes.
• The major derived character of this clade is an
amniotic egg, with four internal membranes.
1. The amnion is a fluid-filled sac surrounding the
embryo.
2. The yolk sac contains a rich store of nutrients for
the developing embryo.

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 19.6 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
3. The chorion (and allantois) enable the embryo to
obtain oxygen from the air and dispose of carbon
dioxide.
4. The allantois also helps dispose of metabolic
waste.

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 19.6 Reptiles are amniotes—tetrapods with a
terrestrially adapted egg
• Reptiles
• include lizards, snakes, turtles, crocodilians, birds,
and extinct dinosaurs,
• have a skin covered with scales and waterproofed
with keratin,
• obtain most of their oxygen using lungs, and
• are ectothermic, absorbing external heat rather
than generating much of their own.

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Figure 19.6a

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Figure 19.6b

Embryo
Amniotic
cavity with Allantois
amniotic fluid Chorion
Amnion

Yolk sac Yolk

(nutrients)
Shell Albumen

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Figure 19.6c

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 Video: Galápagos Marine Iguana

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 Video: Galápagos Tortoise

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 Video: Snake Ritual Wrestling

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 19.7 Birds are feathered reptiles with
adaptations for flight
• Most birds can fly, and nearly every part of their
bodies reflects adaptations that enhance flight.
• Unlike other living reptiles, birds are endothermic,
using heat generated by metabolism to maintain a
warm, steady body temperature.
• Birds typically display very complex behaviors,
particularly during breeding season.

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Figure 19.7a

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Figure 19.7b

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 19.7 Birds are feathered reptiles with
adaptations for flight
• Birds evolved from a lineage of small, two-legged
dinosaurs called theropods.
• Archaeopteryx is the oldest, most primitive known
bird (150 million years old).
• It resembled a small bipedal dinosaur, with teeth,
wing claws, and a long tail with many vertebrae.
• Early feathers may have functioned in
• insulation or
• courtship displays.

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Figure 19.7c

Wing claw (like dinosaur)

Teeth
(like dinosaur)

Long tail with

many vertebrae
(like dinosaur)

Feathers

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 Video: Flapping Geese

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 Video: Soaring Hawk

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 Video: Swans Taking Flight

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 19.8 Mammals are amniotes that have hair
and produce milk
• Mammals are endothermic amniotes with
• hair, which insulates their bodies, and
• mammary glands, which produce milk.
• Mammals have efficient respiratory and circulatory
systems that support their high rate of metabolism.
• Mammalian teeth are differentiated for many kinds
of diets.

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 19.8 Mammals are amniotes that have hair
and produce milk
• Monotremes are egg-laying mammals.
• All other mammals are born rather than hatched.
• The embryos of marsupials and eutherians are
nurtured by a placenta, in which nutrients from the
mother’s blood diffuse into the embryo’s blood.
• Marsupials have a brief gestation and give birth to
tiny, embryonic offspring that complete
development while attached to the mother’s
nipples.
• Eutherians (placental mammals) bear fully
developed live young.
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Figure 19.8a

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Figure 19.8b

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Figure 19.8c

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 Video: Bat Licking Nectar

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 Video: Galápagos Sea Lion

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 Video: Bat Pollinating Agave Plant

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 Video: Wolves’ Agonistic Behavior

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 PRIMATE DIVERSITY

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 19.9 VISUALIZING THE CONCEPT: Many
primate characters are adaptations to life in
the trees
• Primates had evolved as small arboreal mammals
by 65 million years ago.
• Primate characters include
• limber joints,
• grasping hands and feet with flexible digits,
• a short snout, and
• forward-pointing eyes that enhance depth
perception.

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 19.9 VISUALIZING THE CONCEPT: Many
primate characters are adaptations to life in
the trees
• Most living primates are arboreal, and the primate
body has a number of features that were shaped,
through natural selection, by the demands of living
in trees.
• Although humans never lived in trees, the human
body retains many of the traits that evolved in our
arboreal ancestors.
Checkpoint question How do apes and monkeys
differ physically?

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Figure 19.9_1

PRIMATE DIVERSITY A Coquerel’s sifaka,

a lemur

Distinguishing
primate features

• Short snout; eyes set close

together on front of face
• Limber shoulder and
hip joints
• Five highly mobile digits
on hands and feet A slender loris
• Flexible thumb

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Figure 19.9_1a

A slender loris

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Figure 19.9_1b

A Coquerel’s sifaka, a lemur

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Figure 19.9_2

Monkeys
Old World New World
monkeys monkeys
• Many arboreal, • All arboreal
but some ground
dwelling • Nostrils open to
side; far apart
• Nostrils open
downward • Many have a long,
prehensile
• Lack prehensile (grasping) tail
tail

A lion-tailed Golden lion

macaque tamarin

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Figure 19.9_2a

A lion-tailed macaque
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Figure 19.9_2b

Golden lion tamarin

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Figure 19.9_3

Red howler monkey

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Figure 19.9_4
PRIMATE DIVERSITY
Apes
• Include gibbons, orangutans, gorillas, chimpanzees, and humans.
• Compared to other primates, they have larger brains relative to
body size; thus, their behavior is more flexible.
Orangutan Gibbon

Gorilla and
offspring

Chimpanzee
and offspring

Human child
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Figure 19.9_4a

Orangutan
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Figure 19.9_4b

Gorilla and offspring

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Figure 19.9_4c

Gibbon
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Figure 19.9_4d

Chimpanzee and offspring

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Figure 19.9_4e

Human child
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 19.10 The human story begins with our
primate heritage
• A phylogenetic tree shows that all primates are
divided into three groups:
1. lemurs, lorises, and bush babies,
2. tarsiers, and
3. anthropoids, including monkeys and apes.
• The fossil record indicates that anthropoids began
diverging from other primates about 55 million
years ago.

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Figure 19.10a

Lemurs, lorises,
and bush babies

Ancestral
Tarsiers
primate

New World monkeys

Monkeys
Anthropoids
Old World monkeys

Gibbons

Apes
Orangutans

Gorillas

Chimpanzees

Humans

60 50 40 30 20 10 0
Millions of years ago

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Figure 19.10a_1
Lemurs, lorises,
and bush babies
Ancestral
Tarsiers
primate

New World monkeys

Old World monkeys

Gibbons

Orangutans

Gorillas

Chimpanzees

Humans
60 50 40 30 20 10 0
Millions of years ago
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Figure 19.10a_2

Monkeys Apes
Anthropoids

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Figure 19.10b

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 HOMININ EVOLUTION

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 19.11 The hominin branch of the primate tree
includes species that coexisted
• Paleoanthropology, the study of human origins
and evolution, focuses on the tiny slice of
biological history that has occurred since the
divergence of human and chimpanzee lineages
from their common ancestor.
• Paleoanthropologists have found about 20 species
of extinct hominins, species more closely related
to humans than to chimpanzees.
• Some of these species lived at the same time.

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Figure 19.11

0 Paranthropus Homo ?
0.5 robustus ergaster
Paranthropus
1.0 boisei
Homo
1.5 Australopithecus sapiens
africanus Homo
2.0
Australopithecus neanderthalensis
Millions of years ago

2.5 afarensis

3.0 Homo
erectus
3.5 Australopithecus
sediba
4.0 Homo
Kenyanthropus habilis
platyops
4.5
5.0
Ardipithecus
5.5 ramidus

6.0
6.5 Sahelanthropus
7.0 tchadensis

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Figure 19.11_1
0 Paranthropus
0.5 robustus
Paranthropus
1.0 boisei

1.5 Australopithecus
africanus
2.0
Australopithecus
Millions of years ago

2.5 afarensis

3.0
3.5
4.0 Kenyanthropus
4.5 platyops

5.0
Ardipithecus
5.5 ramidus

6.0
6.5 Sahelanthropus
7.0 tchadensis
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Figure 19.11_2
0 Homo ?
0.5 ergaster

1.0
Homo
1.5 sapiens
2.0 Homo
neanderthalensis
Millions of years ago

2.5
Homo
3.0
erectus
Australopithecus
3.5
sediba
Homo
4.0
habilis
4.5
5.0

5.5
6.0
6.5
7.0
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 Checkpoint question Based on the fossil evidence
represented in Figure 19.11, how many hominin
species coexisted 1.7 million years ago?
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 19.12 Australopiths were bipedal and had
small brains
• Present-day humans and chimpanzees clearly
differ in two major features:
1. Humans are bipedal (walk upright) and
2. Humans have much larger brains.
• Bipedalism arose millions of years before larger
brain size.
• A clue to bipedalism is the location of the opening
in the base of the skull through which the spinal
cord exits.

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 Checkpoint question How can
paleoanthropologists conclude that a species
was bipedal based on only a fossil skull?
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Figure 19.12b

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 19.13 Larger brains mark the evolution of
Homo
• The genus Homo includes hominins with larger
brains and evidence of tool use.
• Homo ergaster had a larger brain than H. habilis.
• H. erectus, with a larger brain than H. ergaster,
was the first hominin to spread out of Africa.

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Figure 19.13a

1,500
Homo neanderthalensis

Homo sapiens
1,300
Mean brain volume (cm3)

1,100

900 Homo erectus

Homo ergaster
700
Homo habilis
500 Paranthropus boisei Gorilla
Chimpanzee
300 Australopithecus
afarensis
0 20 40 60 80 100 120
Mean body mass (kg)

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 19.13 Larger brains mark the evolution of
Homo
• Homo neanderthalensis (Neanderthals) had a
brain even larger than ours and hunted big game
with tools made from stone and wood.
• Neanderthals were living in Europe as long as
350,000 years ago and later spread to the Near
East, but by 39,000 years ago, the species was
extinct.

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Figure 19.13b

Atlantic Ocean

Original discovery
(Neander Valley)
Approximate range
Europe of Neanderthals
Asia
Black Sea

Mediterranean Sea

Africa

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 19.14 From origins in Africa, Homo sapiens
spread around the world
• Evidence from fossils and DNA studies has
enabled scientists to trace early human history.
• All living humans have ancestors that originated as
Homo sapiens in Africa.
• The oldest known fossils with the definitive
characteristics of our own species
• were discovered in Ethiopia and
• are 160,000 and 195,000 years old.

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Figure 19.14

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 19.15 SCIENTIFIC THINKING: New
discoveries raise new questions about the
history of hominins
• The interpretation of fossils of small hominins
named Homo floresiensis that were found in
Indonesia is controversial.

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 19.15 SCIENTIFIC THINKING: New
discoveries raise new questions about the
history of hominins
• Some researchers suggest that Homo floresiensis
• was a dwarf descendent of H. erectus,
• is more closely related to Homo habilis than to
Homo erectus, or
• is not a species at all, but instead is Homo sapiens
with a genetic disorder that causes bone
malformations.
• Scientists continue to accumulate further evidence
to determine which hypothesis is correct.

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Figure 19.15

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 19.16 EVOLUTION CONNECTION: Human
skin color reflects adaptations to varying
amounts of sunlight
• Human skin color varies geographically, likely as a
result of natural selection.
• Natural selection may have selected for the
competing abilities of skin to
• block UV radiation, which degrades folate, and
• absorb UV radiation to synthesize vitamin D.
• Folate is vital for fetal development and
spermatogenesis.
• Vitamin D is essential for proper bone development.

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Figure 19.16a

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 Checkpoint question Why didn’t folate degradation
select against lightly pigmented people in
northern latitudes?
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 19.17 CONNECTION: Our knowledge of
animal diversity is far from complete
• Thousands of new species of organisms are
discovered each year.
• The pace of discovery has increased due to
• better access to remote areas and
• new mapping technologies.

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 Checkpoint question What factors are responsible
for the recent increase in the number of new
species found?
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Figure 19.17b

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Figure 19.17c

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 You should now be able to
1. Describe the key derived traits of the chordates
and the chordate subgroups.
2. Describe the characteristics of and distinguish
between each of the following vertebrate groups:
hagfishes, lampreys, chondrichthyans, ray-finned
fishes, lobe-finned fishes, amphibians, reptiles,
birds, and mammals.
3. Describe the transitional species that occupy the
range between fishes and amphibians in
evolutionary history.

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 You should now be able to
4. Distinguish between monotremes, marsupials,
and placental mammals.
5. Compare the three main groups of living
primates.
6. Distinguish between monkeys and apes.
7. Describe the evidence that suggests that
hominins did not evolve in a straight line leading
directly to our species.
8. Describe the evidence that suggests when
upright posture and large brains first evolved in
humans.
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 You should now be able to
9. Describe the relationships between
Neanderthals and modern humans.
10. Describe the unusual characteristics of the
newly discovered Homo floresiensis and its
relationship to other hominins.
11. Describe the adaptive advantages of darker skin
in humans living near the equator but lighter
skin in humans living in northern latitudes.
12. Explain why the total number of animal species
alive today remains an estimate.

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Figure 19.3d_1

Bony skeleton
Dorsal fin
Gills

Operculum Anal fin

Pectoral fin Swim bladder
Pelvic fin
Heart

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Figure 19.3d_2

A rainbow trout,
a ray-fin

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Figure 19.UN01

Common
ancestor of
chordates
19.2 Hagfishes and lampreys lack hinged jaws.

Vertebral column
19.3 Jawed vertebrates with gills and paired fins include
sharks, ray-finned fishes, and lobe-finned fishes.
Jaws

Lungs or lung derivatives 19.4 New fossil discoveries are filling in the gaps of tetrapod evolution.
19.5 Amphibians are tetrapods—vertebrates with two pairs of limbs.
Lobed fins
19.6 Reptiles are amniotes—tetrapods with a terrestrially adapted egg.
Legs
19.7 Birds are feathered reptiles with adaptations for flight.
Amniotic egg
19.8 Mammals are amniotes that have hair and produce milk.
Milk

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Figure 19.UN02
New World
monkeys

Ancestor (a)

(b)

(c)

(d)

(e)

Humans
50 40 30 20 10 0
Millions of years ago
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Figure 19.UN03
Lancelets

Tunicates
Ancestral
chordate
Hagfishes

Lampreys

Sharks, rays
a.
Ray-finned fishes
b.
Lobe-fins
c.
Amphibians
d.
Reptiles
e.

f. Mammals
g.
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