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CAMPBELL
BIOLOGY
TENTH
EDITION
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
34
The Origin and Evolution
of Vertebrates
Lecture Presentation by
Nicole Tunbridge and
Kathleen Fitzpatrick
© 2014 Pearson Education, Inc.
Half a Billion Years of Backbones
 Early in the Cambrian period, about 530 million
years ago, an astonishing variety of invertebrate
animals inhabited Earth’s oceans
 One type of animal gave rise to vertebrates, one of
the most successful groups of animals
 The animals called vertebrates get their name
from vertebrae, the series of bones that make up
the backbone
© 2014 Pearson Education, Inc.
Figure 34.1
What is the relationship between this ancient organism and humans?
© 2014 Pearson Education, Inc.
 One lineage of vertebrates colonized land 365
million years ago
 They gave rise to modern amphibians, reptiles
(including birds), and mammals
 There are more than 57,000 species of
vertebrates, including the largest organisms ever
to live on Earth
 Vertebrates have great disparity, a wide range of
differences within the group
© 2014 Pearson Education, Inc.
The Chordates
1.
Chordates (phylum Chordata) are euterostomes, and have an
internal skeleton, with muscles attached to the outer surface.
A.
Characteristics of Chordates
1.
At some time during their life, all chordates have four basic characteristics.
a.
Notochord
This supporting rod is located dorsally just below the nerve cord.
It provides support and is replaced by the vertebral column in vertebrates.
Dorsal tubular nerve cord
This cord contains a fluid-filled canal.
In vertebrates, this is the spinal cord and it is protected by vertebrae.
Pharyngeal Pouches
These openings function in feeding, gas exchange, or both.
They are seen only during embryonic development in most vertebrates.
In invertebrate chordates, fish, and amphibian larvae, they become functioning
i.
ii.
b.
i.
ii.
c.
i.
ii.
iii.
gills.
iv.
In terrestrial vertebrates, the pouches are modified for various purposes.
v.
In humans, the first pair of pouches becomes the auditory tubes, the second
become tonsils, and the third and fourth pairs become the thymus and parathyroid
glands.
d. A postanal tail extends beyond the anus; in some this only appears in embryos.
© 2014 Pearson Education, Inc.
Concept 34.1: Chordates have a notochord and
a dorsal, hollow nerve cord
 Chordates (phylum Chordata) are bilaterian
animals that belong to the clade of animals known
as Deuterostomia
 Chordates comprise all vertebrates and two
groups of invertebrates, the urochordates and
cephalochordates
© 2014 Pearson Education, Inc.
Phylogeny of living chordates
Figure 34.2
Echinodermata
ANCESTRAL
DEUTEROSTOME
Chordates
Cephalochordata
Urochordata
Notochord
Common ancestor
of chordates
Vertebrates
Myxini
Petromyzontida
Jaws, mineralized skeleton
Lobe-fins
Actinistia
Lungs or lung derivatives
Dipnoi
Lobed fins
Amniotic egg
Mammalia
Milk
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Amniotes
Reptilia
Limbs with digits
Tetrapods
Amphibia
Osteichthyans
Actinopterygii
Gnathostomes
Chondrichthyes
Vertebrae
Figure 34.2a
Phylogeny of living chordates (part 1)
Echinodermata
ANCESTRAL
DEUTEROSTOME
Cephalochordata
Urochordata
Notochord
Common
ancestor of
chordates
Vertebrae
Jaws, mineralized skeleton
© 2014 Pearson Education, Inc.
Myxini
Petromyzontida
Chondrichthyes
Figure 34.2b
Phylogeny of living chordates
(part 2)
Chondrichthyes
Actinopterygii
Jaws, mineralized skeleton
Actinistia
Lungs or lung derivatives
Dipnoi
Lobed fins
Amphibia
Limbs with digits
Reptilia
Mammalia
Amniotic egg
Milk
© 2014 Pearson Education, Inc.
Derived Characters of Chordates
 All chordates share a set of derived characters
 Some species have some of these traits only
during embryonic development
 Four key characters of chordates
 Notochord
 Dorsal, hollow nerve cord
 Pharyngeal slits or clefts
 Muscular, post-anal tail
© 2014 Pearson Education, Inc.
Figure 34.3
Chordate characteristics
Notochord
Dorsal, hollow nerve cord
Muscle
segments
Mouth
Anus
Post-anal tail
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Pharyngeal slits or clefts
Notochord
 The notochord is a longitudinal, flexible rod
between the digestive tube and nerve cord
 It provides skeletal support throughout most of the
length of a chordate
 In most vertebrates, a more complex, jointed
skeleton develops, and the adult retains only
remnants of the embryonic notochord
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Dorsal, Hollow Nerve Cord
 The nerve cord of a chordate embryo develops
from a plate of ectoderm that rolls into a tube
dorsal to the notochord
 The nerve cord develops into the central nervous
system: the brain and the spinal cord
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Pharyngeal Slits or Clefts
 In most chordates, grooves in the pharynx called
pharyngeal clefts develop into slits that open to
the outside of the body
 Functions of pharyngeal slits
 Suspension-feeding structures in many invertebrate
chordates
 Gas exchange in vertebrates (except vertebrates
with limbs, the tetrapods)
 Develop into parts of the ear, head, and neck in
tetrapods
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Muscular, Post-Anal Tail
 Chordates have a tail posterior to the anus
 In many species, the tail is greatly reduced during
embryonic development
 The tail contains skeletal elements and muscles
 It provides propelling force in many aquatic
species
© 2014 Pearson Education, Inc.
B.
Nonvertebrate Chordates
1.
Lancelets
a.
Lancelets are marine chordates, cephalochordates.
b.
Lancelets are named for their resemblance to a lancet—a two-edged surgical knife.
c.
They inhabit shallow coastal waters; they filter feed partly buried in sandy
substrates.
d.
They feed on microscopic particles filtered from a constant stream of water that
enters the mouth and exits through gill slits into an atrium that opens at the atriopore.
e.
Lancelets retain the four chordate characteristics as adults.
f.
The notochord extends from head to tail, accounting for their group name
cephalochordates.
g.
They possess segmented muscles and the dorsal hollow nerve cord has periodic
branches.
2.
Sea Squirts
a.
Sea squirts, or urochordates, are also called tunicates.
b.
Adults have a body composed of an outer tunic; an excurrent siphon squirts out
water when it is disturbed.
c.
The larvae are bilaterally symmetrical and have the four chordate characteristics.
d.
The larvae undergo metamorphosis to develop into sessile adults.
e.
Water passes into a pharynx and out numerous gill slits, the only chordate
characteristic that remains in adults.
f.
It is hypothesized that sea squirts are directly related to vertebrates. A larva with the
four chordate characteristics may have become sexually mature without developing the other
sea squirt characteristics, and then evolved into a fishlike vertebrate.
© 2014 Pearson Education, Inc.
Lancelets
 Lancelets (Cephalochordata) are named for their
bladelike shape
 They are marine suspension feeders that retain
characteristics of the chordate body plan as adults
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Figure 34.UN01
Cephalochordata mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
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Figure 34.4
1 cm
The lancelet Branchiostoma
, a cephalochordate
Cirri
Notochord
Mouth
Dorsal, hollow
nerve cord
Pharyngeal slits
Atrium
Digestive tract
Atriopore
Segmental
muscles
Anus
Tail
© 2014 Pearson Education, Inc.
Figure 34.4a
1 cm
The lancelet Branchiostoma, a cephalochordate (part 1: photo)
© 2014 Pearson Education, Inc.
Tunicates
 Tunicates (Urochordata) are more closely related
to other chordates than are lancelets
 Tunicates most resemble chordates during their
larval stage, which may last only a few minutes
 As an adult, a tunicate draws in water through an
incurrent siphon, filtering food particles
 When attacked, tunicates, or “sea squirts,” shoot
water through their excurrent siphon
© 2014 Pearson Education, Inc.
Figure 34.UN02
Urochordata mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Figure 34.5
A tunicate, a urochordate
Water flow
Notochord
Incurrent
siphon
to mouth
Excurrent
siphon
Dorsal, hollow
nerve cord
Tail
Excurrent
siphon
Incurrent
siphon
Muscle
segments
Intestine
Stomach
Atrium
Pharynx with slits
(a) A tunicate larva
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Excurrent
siphon
Anus
Intestine
Esophagus
Atrium
Pharynx
with
numerous
slits
Tunic
Stomach
(b) An adult tunicate
(c) An adult tunicate
Figure 34.5a
A tunicate, a urochordate (part 1: art)
Water flow
Notochord
Incurrent
siphon
to mouth
Dorsal, hollow
nerve cord
Tail
Excurrent
siphon
Incurrent
siphon
Muscle
segments
Intestine
Stomach
Atrium
Pharynx with slits
(a) A tunicate larva
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Excurrent
siphon
Anus
Intestine
Esophagus
Stomach
(b) An adult tunicate
Atrium
Pharynx
with
numerous
slits
Tunic
Figure 34.5b
A tunicate, a urochordate (part 2: photo
Incurrent siphon
to mouth
Excurrent
siphon
Atrium
Pharynx
with
numerous
slits
Tunic
(c) An adult tunicate
© 2014 Pearson Education, Inc.
 Tunicates are highly derived and have fewer Hox
genes than other vertebrates
© 2014 Pearson Education, Inc.
Early Chordate Evolution
 Ancestral chordates may have resembled
lancelets
 The same Hox genes that organize the vertebrate
brain are expressed in the lancelet’s simple nerve
cord tip
 Sequencing of the tunicate genome indicates that
 Genes associated with the heart and thyroid are
common to all chordates
 Genes associated with transmission of nerve
impulses are unique to vertebrates
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Figure 34.6
Myxini and Petromyzontida mini-tree
BF1
Otx
Hox3
Nerve cord of lancelet embryo
BF1
Otx
Hox3
Brain of vertebrate embryo
(shown straightened)
Forebrain Midbrain
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Hindbrain
29.2 The Vertebrates
A.
Characteristics of Vertebrates
1.
As embryos, vertebrates have the four chordate characteristics.
2.
Vertebrates also have these features:
a.
Vertebral column
i.
The embryonic notochord is replaced by a vertebral column.
ii.
Remnants of the notochord are seen in the intervertebral disks.
iii.
The vertebral column is part of a flexible, strong endoskeleton that is also
evidence of segmentation.
b.
Skull
i.
A skull is an anterior component of the main axis of vertebrate endoskeleton; it
encases the brain.
ii.
The high degree of cephalization in vertebrates is accompanied by complex
sense organs.
iii.
The eyes developed as outgrowths of the brain.
iv.
The ears—equilibrium devices in water—function as sound-wave receivers in
land vertebrates.
c.
Endoskeleton
i.
The endoskeleton and muscles together permit rapid and efficient movement.
ii.
The pectoral and pelvic fins of fish evolved into jointed appendages allowing
vertebrates to move onto land.
d.
Internal organs
i.
Vertebrates possess a complete digestive system and a large coelom.
ii.
The circulatory system is closed and the blood is contained within blood vessels.
iii.
Gills or lungs provide efficient gas exchange.
iv.
The kidneys efficiently excrete nitrogenous waste and regulate water.
v.Pearson Education,
Reproduction
is usually sexual with separate sexes.
© 2014
Inc.
Concept 34.2: Vertebrates are chordates that
have a backbone
 A skeletal system and complex nervous system
have allowed vertebrates efficiency at two
essential tasks
 Capturing food
 Evading predators
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Derived Characters of Vertebrates
 Vertebrates have two or more sets of Hox genes;
lancelets and tunicates have only one cluster
 Vertebrates have the following derived characters
 Vertebrae enclosing a spinal cord
 An elaborate skull
 Fin rays, in the aquatic forms
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Hagfishes and Lampreys
 Fossil evidence shows that the earliest vertebrates
lacked jaws
 Only two lineages of jawless vertebrates remain
today: the hagfishes and the lampreys
 Members of these groups lack a backbone
 The presence of rudimentary vertebrae and the
results of phylogenetic analysis indicate that both
hagfishes and lampreys are vertebrates
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 Together, the hagfishes and lampreys form a
clade of living jawless vertebrates, the
cyclostomes
 Vertebrates with jaws make up a much larger
clade, the gnathostomes
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Figure 34.UN03
Myxini and Petromyzontida mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Hagfishes
 Hagfishes (Myxini) are jawless vertebrates that
have a cartilaginous skull, reduced vertebrae, and
a flexible rod of cartilage derived from the
notochord
 They have a small brain, eyes, ears, and tooth-like
formations
 Hagfishes are marine; most are bottom-dwelling
scavengers
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Figure 34.7
A hagfish
Slime glands
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Lampreys
 Lampreys (Petromyzontida) are parasites that
feed by clamping their mouth onto a live fish
 They inhabit various marine and freshwater
habitats
 They have cartilaginous segments surrounding the
notochord and arching partly over the nerve cord
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Figure 34.8
A sea lamprey
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Figure 34.8a
A sea lamprey (part 1: lamprey)
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Figure 34.8b
A sea lamprey (part 2: lamprey mouth)
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B.
Vertebrate Evolution
1.
Chordates (including vertebrates) appeared at the start
of the Cambrian period.
2.
The earliest vertebrates were fishes; most of which have
jaws.
3.
Jawed fish and other vertebrates are gnathostomes—
animals with jaws.
4.
Fish also had a bony skeleton, lungs, and fleshy fins,
which were preadaptive for a land existence.
5.
Amphibians are the first vertebrates to live on land and to
have four limbs (tetrapods).
6.
Amphibians are not fully adapted to living on land
because they still have to reproduce in an aquatic environments.
7.
Reptiles are fully adapted to living on land because they
produce an amniotic egg.
8.
Amniotes develop within an aquatic environment but of
their own making.
9.
In placental mammals, the fertilized egg develops inside
the female, where it is surrounded by an amniotic membrane.
10. Another feature for living on land includes watertight skin, and
can be seen in reptiles and mammals.
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Early Vertebrate Evolution
 Fossils from the Cambrian explosion document
the transition to craniates
 The most primitive of the fossils are those of the 3cm-long Haikouella
 Haikouella had a well-formed brain, eyes, and
muscular segments, but no skull or ear organs
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Fossil of an early chordate
Figure 34.9
5 mm
Segmented muscles
Pharyngeal slits
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Figure 34.9a
Fossil of an early chordate (part 1: photo)
5 mm
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The Fishes
1.
Fishes are the largest group of vertebrates with
nearly 28,000 recognized species.
A.
Jawless Fishes
1.
Small, jawless, and finless ostracoderms are the earliest
vertebrate fossils.
2.
Today’s jawless fishes, or agnathans have a cartilaginous
skeleton and persistent notochord.
3.
They have smooth nonscaly skin.
4.
They have cylindrical bodies and are up to a meter long.
5.
Many lampreys are filter feeders similar to their ancestors.
6.
Parasitic lampreys have a round muscular mouth equipped
with teeth; they attach themselves to fish and suck nutrients from the
host’s circulatory system.
7.
Marine parasitic lampreys entered the Great Lakes and
devastated the trout population in the 1950s.
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 Conodonts were among the earliest vertebrates
in the fossil record, dating from 500 to 200 million
years ago
 They had mineralized skeletal elements in their
mouth and pharynx
 Their fossilized dental elements are common in
the fossil record
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Figure 34.10
A conodont
Dental elements
(within
head)
0.5 cm
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 Other groups of jawless vertebrates were armored
with defensive plates of bone on their skin
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Figure 34.11
Jawless armored vertebrates
Pteraspis
Pharyngolepis
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Origins of Bone and Teeth
 Mineralization appears to have originated with
vertebrate mouthparts
 The vertebrate endoskeleton became fully
mineralized much later
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B.
Fishes with Jaws
1.
Fishes with jaws have:
a.
Ectothermy—they depend on the environment to regulate their body temperature.
b.
Gills are used for gas exchange.
i.
Jawed fish have a single-looped, closed circulatory pathway with a heart that pumps the blood first
to the gills (for oxygen exchange) and then to the rest of the body.
c.
Cartilaginous or bony endoskeleton—the endoskeleton of jawed fishes includes the vertebral
column, a skull with jaws, and paired pectoral and pelvic fins.
i.
Jaws evolved from the first pair of gill arches of agnathans; the second pair of arches
became support structures for the jaws.
d.
Scales cover and protect the skin.
2.
Placoderms are extinct jawed fishes of the Devonian Period.
a.
They were armored with heavy plates and had strong jaws.
b.
Like extant fishes, they had paired pectoral and pelvic fins.
c.
Paired fins allow a fish to balance and maneuver well in water; this helps predation.
3.
Cartilaginous Fishes
a.
Sharks, rays, skates, and chimaeras are marine cartilaginous fishes (Chondrichthyes).
b.
They have a cartilaginous skeleton rather than bone.
c.
Five to seven gill slits are on both sides of the pharynx; they lack the gill covers found on bony fish.
d.
They have many openings to the gill chamber located behind the eyes called spiracles.
e.
Their body is covered with dermal denticles.
f.
The teeth of sharks are enlarged scales; there are many rows of replacement teeth growing behind
the front teeth.
g.
They have three well developed senses to detect prey:
i.
The ability to sense electric currents in water;
ii.
A lateral line system senses pressure caused by fish swimming nearby and;
iii.
They have a keen sense of smell.
h.
The largest sharks are filter feeders, not predators; the basking and whale sharks eat tons of
crustacea.
i.
Most sharks are fast, open-sea predators; a great white shark eats dolphins, sea lions and seals.
© 2014 Pearson Education, Inc.
Concept 34.3: Gnathostomes are vertebrates
that have jaws
 Today, jawed vertebrates, or gnathostomes,
outnumber jawless vertebrates
 Gnathostomes include sharks and their relatives,
ray-finned fishes, lobe-finned fishes, amphibians,
reptiles (including birds), and mammals
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Derived Characters of Gnathostomes
 Gnathostomes (“jaw mouth”) are named for their
jaws, hinged structures that, especially with the
help of teeth, are used to grip food items firmly
and slice them
 The jaws are hypothesized to have evolved by
modification of skeletal rods that supported the
pharyngeal (gill) slits
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Figure 34.12
Possible step in the evolution of jawbones
Gill slits
Skeletal
rods
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Cranium
Modified
skeletal rods
 Other characters common to gnathostomes
 Genome duplication, including duplication of Hox
genes
 An enlarged forebrain associated with enhanced
smell and vision
 In aquatic gnathostomes, the lateral line system,
which is sensitive to vibrations
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Fossil Gnathostomes
 The earliest gnathostomes in the fossil record are
an extinct lineage of armored vertebrates called
placoderms
 They appeared about 440 million years ago
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Figure 34.13
Fossil of an early gnathostome…Dunkleosteus could exert a force of
8000 pounds per square inch.
0.5 m
© 2014 Pearson Education, Inc.
 Another group of jawed vertebrates called
acanthodians radiated during the Silurian and
Devonian periods (444 to 359 million years ago)
 Three lineages of jawed vertebrates survive today:
chondrichthyans, ray-finned fishes, and lobe-fins
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Chondrichthyans (Sharks, Rays, and Their
Relatives)
 Chondrichthyans (Chondrichthyes) have a
skeleton composed primarily of cartilage
 The largest and most diverse group of
chondrichthyans includes the sharks, rays, and
skates
© 2014 Pearson Education, Inc.
Figure 34.UN04
Chondrichthyes mini-tree,
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Figure 34.14
Dorsal fins
Pectoral fins
Pelvic fins
(a) Blacktip reef shark
(Carcharhinus melanopterus)
(c) Spotted ratfish (Hydrolagus colliei)
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(b) Southern stingray (Dasyatis americana)
Figure 34.14a
Dorsal fins
Pectoral fins
Pelvic fins
(a) Blacktip reef shark
(Carcharhinus melanopterus)
© 2014 Pearson Education, Inc.
j.
Rays and skates live on the ocean floor; their pectoral fins are
enlarged into winglike fins and they swim slowly.
k.
Stingrays have a venomous spine.
l.
Electric rays feed on fish that have been stunned with an
electric shock that may reach over 300 volts.
m.
Sawfish rays have a large anterior “saw” that they use to slash
through schools of fish.
n. Chimaeras (ratfishes) live in cold marine waters and are known for
their unusual shape and iridescent colors.
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Figure 34.14b
(b) Southern stingray (Dasyatis americana)
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Figure 34.14c
(c) Spotted ratfish (Hydrolagus colliei)
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Video: Manta Ray
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 A second subclass is composed of a few dozen
species of ratfishes, or chimaeras
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 Sharks have a streamlined body and are swift
swimmers
 The largest sharks are suspension feeders, but
most are carnivores
 Sharks have a short digestive tract with a ridge
called the spiral valve to increase the digestive
surface area
 Sharks have acute senses including sight, smell,
and the ability to detect electrical fields from
nearby animals
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 Shark eggs are fertilized internally but embryos
can develop in different ways
 Oviparous: Eggs hatch outside the mother’s body
 Ovoviviparous: The embryo develops within the
uterus and is nourished by the egg yolk
 Viviparous: The embryo develops within the uterus
and is nourished through a yolk sac placenta from
the mother’s blood
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 The reproductive tract, excretory system, and
digestive tract empty into a common cloaca
 Today, sharks are severely threatened by
overfishing; Pacific populations have plummeted
by up to 95%
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Ray-Finned Fishes and Lobe-Fins
 The vast majority of vertebrates belong to a clade
of gnathostomes called Osteichthyes
 Nearly all living osteichthyans have a bony
endoskeleton
 Osteichthyans include the bony fishes and
tetrapods
 Aquatic osteichthyans are the vertebrates we
informally call fishes
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Figure 34.UN05
Actinopterygii, Actinistia, and Dipnoi mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
 Most fishes breathe by drawing water over gills
protected by an operculum
 Fishes control their buoyancy with an air sac
known as a swim bladder
 Fishes have a lateral line system
 Most species are oviparous, but some have
internal fertilization and birthing
© 2014 Pearson Education, Inc.
4.
Bony Fishes
a.
There are about 25,000 species of bony fishes (Osteichthyes).
b.
Bony fishes have a skeleton of bone; most are ray-finned with thin, bony
rays supporting the fins.
c.
The gills of bony fishes do not open separately but instead are covered by
an operculum.
d.
The swim bladder is a gas-filled sac whose pressure can be altered to
regulate buoyancy and depth.
e.
Bony fish have a single-loop, closed cardiovascular system.
f.
They have a well-developed nervous system.
g.
Fish sperm and eggs are usually shed into water.
h.
For most fish, the fertilization and embryonic development occur outside
the female’s body.
i.
The lobe-finned fishes include six species of lungfishes and two species
of coelacanth.
i.
Their fleshy fins are supported by central bones.
ii.
Lungfishes have lungs and gills for gas exchange.
iii.
Lungfishes and lobe-finned fishes are grouped together as the
Sarcopterygii.
iv.
Lungfishes live in stagnant freshwater or in ponds that dry up annually;
they are found in Africa, South America, and Australia.
v.
Coelacanths live in deep oceans; once considered extinct, more than 200
have been captured since 1938.
© 2014 Pearson Education, Inc.
Figure 34.15
Anatomy of a trout, a ray-finned fish
Cut edge
of operculum
Swim
Spinal cord bladder
Dorsal fin
Brain
Adipose fin
(characteristic
of trout)
Caudal
fin
Nostril
Anal fin
Gills
Kidney
© 2014 Pearson Education, Inc.
Liver
Heart
Stomach
Anus
Gonad
Pelvic
Intestine
fin
Lateral line
Urinary
bladder
Ray-Finned Fishes
 Actinopterygii, the ray-finned fishes, include
nearly all the familiar aquatic osteichthyans
 Ray-finned fishes originated during the Silurian
period (444 to 416 million years ago)
 The fins, supported mainly by long, flexible rays,
are modified for maneuvering, defense, and other
functions
© 2014 Pearson Education, Inc.
▼
Figure 34.16
Red
lionfish
(Pterois
volitans)
Yellowfin tuna (Thunnus albacares)
▼
Ray-finned fishes
(Actinopterygii)
▼
▼
© 2014 Pearson Education, Inc.
Common sea
horse,
(Hippocampus
ramulosus)
Fine-spotted
moray eel,
(Gymnothorax
dovii)
Video: Clownfish and Anemone
© 2014 Pearson Education, Inc.
Video: Coral Reef
© 2014 Pearson Education, Inc.
Video: Seahorse Camouflage
© 2014 Pearson Education, Inc.
 Industrial-scale fishing operations have driven
many ray-finned fish populations to collapse
 Populations are also affected by dams that change
water flow patterns, affecting prey capture,
migration, and spawning
© 2014 Pearson Education, Inc.
Lobe-Fins
 The lobe-fins (Sarcopterygii) also originated in the
Silurian period
 They have muscular pelvic and pectoral fins that
they use to swim and “walk” underwater across
the substrate
© 2014 Pearson Education, Inc.
Figure 34.17
A reconstruction of an ancient lobe-fin—discovered in 2009
5 cm
Lower
jaw
© 2014 Pearson Education, Inc.
Scaly
covering
Dorsal
spine
Figure 34.17a
A reconstruction of an ancient lobe-fin (part 1: photo)
5 cm
Lower
jaw
© 2014 Pearson Education, Inc.
Scaly
covering
Dorsal
spine
 Three lineages survive and include coelacanths,
lungfishes, and tetrapods
 Coelacanths were thought to have become extinct
75 million years ago, but a living coelacanth was
caught off the coast of South Africa in 1938
© 2014 Pearson Education, Inc.
Figure 34.18
A coelacanth (Latimeria)
© 2014 Pearson Education, Inc.
 The living lungfishes are all found in the Southern
Hemisphere
 Though gills are the main organs for gas
exchange, they can also surface to gulp air into
their lungs
 The third surviving lineage of lobe-fins are
tetrapods, a group that adapted to life on land
© 2014 Pearson Education, Inc.
29.4 The Amphibians
1.
Amphibians have the following characteristics:
a.
They are tetrapods; they have four limbs.
i.
The skeleton is well-developed for locomotion.
b.
Amphibians have smooth and nonscaly skin.
i.
The moist skin plays an active role in water balance, respiration, and temperature
regulation.
c.
Amphibians usually have small lungs supplemented by gas exchange across
porous skin.
d.
The single-loop circulatory path of fish is replaced by a
closed double-loop circulatory system; however oxygen-rich blood mixes with some oxygen-poor blood.
i.
A three-chambered heart with a single ventricle pumps and two atria pumps blood
to both the lungs and body.
e.
Amphibians have sense organs that are adapted to life on land.
i.
The brain is larger than that of fishes; their cerebral cortex is more developed.
ii.
A specialized tongue is used for catching prey.
iii.
The eyelids keep their eyes moist.
iv.
Amphibian ears are adapted for detecting sound waves; in turn, the larynx
produces sounds.
f.
Amphibians are ectothermic, depending upon the environment to regulate body
temperature.
i.
If winter temperature drops too low, temperate ectotherms become inactive and
enter torpor.
g.
Amphibians return to the water to reproduce.
i.
They shed eggs into the water for external fertilization.
ii.
Generally, amphibian eggs are protected by a coat of jelly but not by a shell.
iii.
The young hatch into aquatic larvae with gills (tadpoles).
iv.
The aquatic larvae usually undergo metamorphosis to develop into a terrestrial
adult.
v.
Some amphibians evolved mechanisms that allow them to bypass the aquatic
larval stage.
© 2014 Pearson Education, Inc.
Concept 34.4: Tetrapods are gnathostomes that
have limbs
 One of the most significant events in vertebrate
history was when the fins of some lobe-fins
evolved into the limbs and feet of tetrapods
© 2014 Pearson Education, Inc.
Derived Characters of Tetrapods
 Tetrapods have some specific adaptations
 Four limbs, and feet with digits
 A neck, which allows separate movement of the
head
 Fusion of the pelvic girdle to the backbone
 The absence of gills (except some aquatic species)
 Ears for detecting airborne sounds
© 2014 Pearson Education, Inc.
A.
Evolution of Amphibians
1.
Amphibians evolved from the lobe-finned fishes with lungs by way of
transitional forms.
2.
Two hypotheses describe evolution of amphibians from lobe-finned fishes.
a.
Lobe-finned fishes that could move from pond-to-pond had an advantage over
those that could not.
b.
The supply of food on land and the absence of predators promoted adaptation to
land.
3.
Paleontologists found a fossil, Tiktaalik roseae, from the late Devonian period in
Arctic Canada that represents an intermediate between lobe-finned fishes and tetrapods with
limbs.
B.
Diversity of Living Amphibians
1.
Modern amphibians include three groups: salamanders and newts,
frogs and toads, and caecilians.
2.
Salamanders and newts have a long body and tail, and two pairs of legs
3.
Their S-shaped locomotion is similar to fish movements.
4.
Salamanders and newts are carnivorous, feeding on insects, snails, etc.
5.
Salamanders practice internal fertilization; the males produce a spermatophore that
females pick up with the cloaca (the common receptacle for the urinary, genital, and digestive
canals).
6.
Frogs and toads are tailless as adults; the hind limbs are specialized for jumping.
7.
Glands in the skin secrete poisons; some tropical species often have brilliant
warning coloration.
8.
Frogs and toads have the head and trunk fused; frogs live near or in fresh water
while toads live in damp places away from water.
9.
Caecilians are legless; most burrow in soil and feed on worms, etc.
© 2014 Pearson Education, Inc.
The Origin of Tetrapods
 Tiktaalik, nicknamed a “fishapod,” shows both fish
and tetrapod characteristics
 It had
 Fins, gills, lungs, and scales
 Ribs to breathe air and support its body
 A neck and shoulders
 Fins with the bone pattern of a tetrapod limb
© 2014 Pearson Education, Inc.
Figure 34.19
Fish
Characters
Tetrapod
Characters
Scales
Fins
Gills and lungs
Neck
Ribs
Fin skeleton
Flat skull
Eyes on top of skull
Discovery of a “fishapod”: Tiktaalik
Shoulder bones
Ribs
Neck
Scales
Head
Eyes on top
of skull
Humerus
Flat skull
Ulna
“Wrist”
Elbow
Radius
Fin
© 2014 Pearson Education, Inc.
Fin skeleton
Figure 34.19a
Shoulder bones
Neck
Head
Eyes on top
of skull
Flat skull
Fin
© 2014 Pearson Education, Inc.
Figure 34.19b
Ribs
© 2014 Pearson Education, Inc.
Figure 34.19c
Scales
© 2014 Pearson Education, Inc.
Figure 34.19d
Humerus
Ulna
“Wrist”
Elbow
Radius
Fin skeleton
© 2014 Pearson Education, Inc.
 Tiktaalik could most likely prop itself on its fins, but
not walk
 The first tetrapods appeared 365 million years ago
© 2014 Pearson Education, Inc.
Figure 34.20
Lungfishes
Steps in the origin of limbs with digits
Eusthenopteron
Panderichthys
Tiktaalik
Acanthostega
Limbs
with digits
Tulerpeton
Amphibians
Amniotes
Silurian
Devonian
PALEOZOIC
Carboniferous
Permian
415 400 385 370 355 340 325 310 295 280 265 0
Time (millions of years ago)
© 2014 Pearson Education, Inc.
Key to
limb bones
Ulna
Radius
Humerus
Figure 34.20a
Lungfishes
Eusthenopteron
Panderichthys
Tiktaalik
Lobe-fins with limbs with digits
Silurian
Devonian
PALEOZOIC
Carboniferous
Permian
415 400 385 370 355 340 325 310 295 280 265 0
Time (millions of years ago)
© 2014 Pearson Education, Inc.
Key to
limb bones
Ulna
Radius
Humerus
Figure 34.20b
Acanthostega
Limbs
with digits
Tulerpeton
Amphibians
Amniotes
Silurian
Devonian
PALEOZOIC
Carboniferous
Permian
415 400 385 370 355 340 325 310 295 280 265 0
Time (millions of years ago)
© 2014 Pearson Education, Inc.
Key to
limb bones
Ulna
Radius
Humerus
Amphibians
 Amphibians (class Amphibia) are represented by
about 6,150 species in three clades
 Urodela (salamanders)
 Anura (frogs)
 Apoda (caecilians)
© 2014 Pearson Education, Inc.
Figure 34.UN06
Amphibia mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Salamanders
 Salamanders (urodeles) are amphibians with tails
 Some are aquatic, but others live on land as adults
or throughout life
 Paedomorphosis, the retention of juvenile features
in sexually mature organisms, is common in
aquatic species
© 2014 Pearson Education, Inc.
Figure 34.21
(b) Order Anura
(a) Order Urodela
Amphibians
(c) Order Apoda
© 2014 Pearson Education, Inc.
Figure 34.21a
(a) Order Urodela
© 2014 Pearson Education, Inc.
Frogs
 Frogs (anurans) lack tails and have powerful hind
legs for locomotion on land
 Frogs with leathery skin are called “toads”
© 2014 Pearson Education, Inc.
Figure 34.21b
Amphibians (part 2: frogs and toads)
(b) Order Anura
© 2014 Pearson Education, Inc.
Caecilians
 Caecilians (apoda) are legless, nearly blind, and
resemble earthworms
 The absence of legs is a secondary adaptation
© 2014 Pearson Education, Inc.
Figure 34.21c
Amphibians (part 3: caecilians)
(c) Order Apoda
© 2014 Pearson Education, Inc.
Lifestyle and Ecology of Amphibians
 Amphibian means “both ways of life,” referring to
the metamorphosis of an aquatic larva into a
terrestrial adult
 Tadpoles are herbivores that lack legs, but legs,
lungs, external eardrums, and adaptations for
carnivory may all arise during metamorphosis
 Most amphibians have moist skin that
complements the lungs in gas exchange
© 2014 Pearson Education, Inc.
The “dual life” of a frog (Rana temporaria)
Figure 34.22
(a) The tadpole
© 2014 Pearson Education, Inc.
(b) During metamorphosis
(c) The adults return to water to mate.
Figure 34.22a
(a) The tadpole
© 2014 Pearson Education, Inc.
Figure 34.22b
(b) During metamorphosis
© 2014 Pearson Education, Inc.
Figure 34.22c
(c) The adults return to water to mate.
© 2014 Pearson Education, Inc.
 Fertilization is external in most species, and the
eggs require a moist environment
 In some species, males or females care for the
eggs on their back, in their mouth, or in their
stomach
© 2014 Pearson Education, Inc.
Figure 34.23
A mobile nursery
© 2014 Pearson Education, Inc.
 Amphibian populations have been declining in
recent decades
 The causes include a disease-causing chytrid
fungus, habitat loss, climate change, and pollution
© 2014 Pearson Education, Inc.
The Reptiles
1.
Reptiles (class Reptilia) are a successful group of terrestrial animals.
2.
Reptiles have many characteristics showing that they are fully adapted to living on
land.
a.
Reptiles have paired limbs adapted for climbing, running, paddling, or flying.
b.
Reptiles have a thick, scaly skin that is impermeable to water.
i.
Reptile’s protective skin prevents water loss but it also requires several
molts a year.
3.Reptiles have efficient breathing - their lungs are more developed than in amphibians; air
rhythmically moves in and out of the lungs due to an expandable rib cage.
4.Reptiles have efficient circulation. The heart prevents mixing of blood. Oxygen-rich blood is
more fully separated from oxygen-poor blood.
5.Reptiles have efficient excretion. The kidneys are well-developed and excrete uric acid so
less water is required.
6.Reptiles are ectothermic.
i.
They require a fraction of the food per body weight of birds and mammals.
ii.
They are behaviorally adapted to warm their body temperature by sunbathing.
Reptiles have well-adapted reproduction.
i.
The sexes are separate and fertilization is internal.
ii.
The amniotic egg contains extraembryonic membranes.
iii.
Extraembryonic membranes are not a part of the embryo
and are disposed of after development.
iv.
They protect the embryo, remove nitrogenous wastes, and provide oxygen, food,
and water.
v.
The amnion is one extraembryonic membrane; it fills with fluid to provide a “pond”
for the embryo to develop.
© 2014 Pearson Education, Inc.
Concept 34.5: Amniotes are tetrapods that have
a terrestrially adapted egg
 Amniotes are a group of tetrapods whose living
members are the reptiles, including birds, and
mammals
© 2014 Pearson Education, Inc.
†Parareptiles
Turtles
Crocodilians
Archosaurs
Reptiles
†Pterosaurs
†Ornithischian
ANCESTRAL
AMNIOTE
dinosaurs
Saurischians
Diapsids
Dinosaurs
A phylogeny of
amniotes
Figure 34.24
†Saurischian
dinosaurs
other than birds
Birds
†Plesiosaurs
†Ichthyosaurs
Lepidosaurs
Synapsids
© 2014 Pearson Education, Inc.
Tuataras
Squamates
(lizards and
snakes)
Mammals
Figure 34.24a
†Parareptiles
Turtles
†Pterosaurs
†Ornithischian
Saurischians
Diapsids
Dinosaurs
Archosaurs
Reptiles
© 2014 Pearson Education, Inc.
Crocodilians
dinosaurs
† Saurischian
dinosaurs
other than
birds
Birds
Figure 34.24b
Diapsids
†Plesiosaurs
†Ichthyosaurs
Lepidosaurs
Synapsids
© 2014 Pearson Education, Inc.
Tuataras
Squamates
(lizards and
snakes)
Mammals
A.
Evolution of Amniotes
1.
The amniotes consist of three lineages:
a.
The turtles, in which the skull is anapsid, having no openings behind the
orbit—eye socket.
b.
All the other reptiles, in which the skull has two openings behind the orbit
(diapsid).
c.
The mammals, in which the skull has one opening behind the orbit
(synapsid).
2.
The reptiles have no common ancestor; they are a paraphyletic group
and not a monophyletic group.
3.
Thecodonts are diapsids that gave rise to the ichthyosaurs, which
returned to the aquatic environment, and the pterosaurs, which were terrestrial.
a.
The pterosaurs of the Jurassic period had a keel for attachment
of flight muscles and air spaces in bones to reduce weight.
b.
The thecodonts gave rise to the crocodiles and dinosaurs.
4.
Dinosaurs varied in size and behavior; some had a bipedal stance and
gave rise to birds.
5.
Dinosaurs dominated the earth for about 170 million years; then most
died out at the end of the Cretaceous period (65 MYA).
6.
One theory of mass extinction:
a.
A massive meteorite struck the Earth near the
Yucatán Peninsula, resulting in cataclysmic events disrupting existing ecosystems,
destroying many living things.
b.
An iridium layer, a mineral common in meteorites,
occurs in rocks at the end of this period.
© 2014 Pearson Education, Inc.
Derived Characters of Amniotes
 Amniotes are named for the major derived
character of the clade, the amniotic egg, which
contains membranes that protect the embryo
 The extraembryonic membranes are the amnion,
chorion, yolk sac, and allantois
© 2014 Pearson Education, Inc.
Figure 34.25
The amniotic egg
Extraembryonic membranes
Allantois
Chorion
Amniotic cavity
with amniotic fluid
Embryo
Yolk
(nutrients)
Albumen
Shell
Amnion
Yolk sac
Extraembryonic membranes
© 2014 Pearson Education, Inc.
 The amniotic egg was a key adaptation to life on
land
 The amniotic eggs of most reptiles and some
mammals have a shell
 Amniotes have other terrestrial adaptations, such
as relatively impermeable skin and the ability to
use the rib cage to ventilate the lungs
© 2014 Pearson Education, Inc.
Early Amniotes
 Living amphibians and amniotes split from a
common ancestor about 350 million years ago
 Early amniotes were more tolerant of dry
conditions than the first tetrapods
 The earliest amniotes were small predators with
sharp teeth and long jaws
© 2014 Pearson Education, Inc.
Figure 34.26
Artist’s reconstruction of Hylonomus, an early amniote
© 2014 Pearson Education, Inc.
Reptiles
 The reptile clade includes the tuataras, lizards,
snakes, turtles, crocodilians, birds, and some
extinct groups
 Reptiles have scales that create a waterproof
barrier
 Most reptiles lay shelled eggs on land
© 2014 Pearson Education, Inc.
Figure 34.UN07
Reptilia mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Figure 34.27
Hatching reptiles
© 2014 Pearson Education, Inc.
 Most reptiles are ectothermic, absorbing external
heat as the main source of body heat
 Ectotherms regulate their body temperature
through behavioral adaptations
 Birds are endothermic, capable of maintaining
body temperature through metabolism
© 2014 Pearson Education, Inc.
The Origin and Evolutionary Radiation of
Reptiles
 Fossil evidence indicates that the earliest reptiles
lived about 310 million years ago
 The first major group to emerge were
parareptiles, which were mostly large, stocky
quadrupedal herbivores
© 2014 Pearson Education, Inc.
 As parareptiles were dwindling, the diapsids were
diversifying
 The diapsids consisted of two main lineages: the
lepidosaurs and the archosaurs
 The lepidosaurs include tuataras, lizards, snakes,
and extinct mososaurs
 The archosaur lineage produced the crocodilians,
pterosaurs, and dinosaurs
© 2014 Pearson Education, Inc.
 Pterosaurs were the first tetrapods to exhibit flight
 The dinosaurs diversified into a vast range of
shapes and sizes
 They included bipedal carnivores called
theropods, the group from which birds are
descended
© 2014 Pearson Education, Inc.
 Fossil discoveries and research have led to the
conclusion that many dinosaurs were agile and
fast moving
 Paleontologists have also discovered signs of
parental care among dinosaurs
 Some anatomical evidence supports the
hypothesis that at least some dinosaurs were
endotherms
© 2014 Pearson Education, Inc.
 Dinosaurs, with the exception of birds, became
extinct by the end of the Cretaceous
 Their extinction may have been partly caused by
an asteroid
© 2014 Pearson Education, Inc.
C.
Diversity of Living Reptiles
1.
Most reptiles today live in the tropics or subtropics; lizards and snakes
live on soil; turtles, crocodiles, and alligators live in water.
2.
Turtles have a heavy shell fused to the ribs and to the thoracic
vertebrae.
a.
Turtles lack teeth but use a sharp beak.
b.
Sea turtles must return to shore to lay eggs.
3.
Lizards have four clawed legs and are carnivorous.
a.
Marine iguanas on the Galápagos Islands are adapted to spending
time at sea.
b.
Chameleons live in trees, have a long sticky tongue to catch insects,
and change color.
c.
Geckos are primarily nocturnal and have adhesive pads on their toes.
d.
Skinks have reduced limbs and shiny scales.
4.
Snakes evolved from lizards and lost legs as an adaptation to
burrowing.
a.
Their jaws can readily dislocate to engulf large food.
b.
A tongue collects airborne molecules to transfer them to Jacobson’s
organ for tasting.
c.
Some snakes are poisonous and have special fangs to inject venom.
d.
Snakes have internal ears that can detect low-frequency sounds and
vibrations.
5.
Tuataras are lizardlike animals found in New Zealand.
a.
They possess a well-developed “third eye,” which is light sensitive
and buried beneath the skin in the upper part of the head.
b.
They are the only member of an ancient group of reptiles that
© 2014 Pearson Education, Inc.
included the common ancestor of modern lizards and snakes.
Turtles
 The phylogenetic position of turtles remains
uncertain
 All turtles have a boxlike shell made of upper and
lower shields that are fused to the vertebrae,
clavicles, and ribs
© 2014 Pearson Education, Inc.
Figure 34.28
(a) Eastern box turtle (Terrapene carolina
carolina)
Extant reptiles (other than birds
(d) Wagler’s pit viper
(b) Tuatara (Sphenodon punctatus)
(Tropidolaemus wagleri)
(c) Australian thorny
devil lizard
(Moloch horridus)
(e) American alligator (Alligator
mississippiensis)
© 2014 Pearson Education, Inc.
Figure 34.28a
(a) Eastern box turtle (Terrapene carolina carolina)
© 2014 Pearson Education, Inc.
Figure 34.28b
(b) Tuatara (Sphenodon punctatus)
© 2014 Pearson Education, Inc.
Figure 34.28c
(c) Australian thorny devil lizard (Moloch horridus)
© 2014 Pearson Education, Inc.
Figure 34.28d
(d) Wagler’s pit viper (Tropidolaemus wagleri)
© 2014 Pearson Education, Inc.
Figure 34.28e
(e) American alligator (Alligator mississippiensis)
© 2014 Pearson Education, Inc.
Video: Galápagos Marine Iguana
© 2014 Pearson Education, Inc.
Video: Snake Ritual Wrestling
© 2014 Pearson Education, Inc.
Video: Galápagos Tortoise
© 2014 Pearson Education, Inc.
 Some turtles have adapted to deserts and others
live entirely in ponds and rivers
 The largest turtles live in the sea
 Many species of sea turtles are endangered by
accidental capture in fishing nets or development
of beaches where they lay eggs
© 2014 Pearson Education, Inc.
 Snakes are legless lepidosaurs that evolved from
lizards
 Snakes are carnivorous, and have adaptations to
aid in capture and consumption of prey including
 Chemical sensors
 Heat-detecting organs
 Venom
 Loosely articulated jawbones and elastic skin
© 2014 Pearson Education, Inc.
Crocodilians
 Crocodilians (alligators and crocodiles) belong to
an archosaur lineage that dates back to the late
Triassic
 Living crocodilians are restricted to warm regions
© 2014 Pearson Education, Inc.
D.
Birds
Birds share a common ancestor with crocodilians and have scales, a tail with vertebrae, and clawed
feet.
Feathers keep birds warm, and help birds fly and steer.
Feathers are modified scales.
Birds molt and replace their feathers annually.
Birds have a modified skeleton.
The collarbone is fused and the sternum has a keel.
Other bones are fused to make the skeleton more rigid than the reptilian skeleton.
The breast muscles are attached to the keel.
Birds have modified respiration.
Bird respiratory air sacs are extensive, even extending into some larger bones.
i.
Using a one-way flow of air, air sacs maximize gas exchange and oxygenation of blood.
ii.
Efficient supply of oxygen to muscles is vital for the level of muscle activity needed for
flight.
Birds are endothermic; they have the ability to maintain a constant, relatively high body temperature.
Birds have well-developed sense organs and nervous system.
Birds have very acute vision.
Birds’ muscle reflexes are excellent.
Bird migration allows use of widespread food sources; an enlarged portion of the brain is responsible
for instinctive behaviors.
E.
Diversity of Living Birds
Most birds can fly; some, however, some are flightless.
Bird classification is based on beak and foot types, and to some extent on habitats and behaviors.
Birds of prey have notched beaks and sharp talons.
Shorebirds have long slender bills and long legs.
Waterfowl have webbed toes and broad bills.
© 2014 Pearson Education, Inc.
Birds
 Birds are archosaurs, but almost every feature of
their reptilian anatomy has undergone modification
in their adaptation to flight
© 2014 Pearson Education, Inc.
Derived Characters of Birds
 Many characters of birds are adaptations that
facilitate flight
 The major adaptation is wings with keratin
feathers
 Other adaptations include lack of a urinary
bladder, females with only one ovary, small
gonads, and loss of teeth
© 2014 Pearson Education, Inc.
Figure 34.29
Form fits function: the avian wing and feather
Finger 1
(b) Bone structure
Palm
Finger 2
(a) Wing
Finger 3
Forearm
Vane
Shaft
Wrist
Shaft
Barb
Barbule
Hook
(c) Feather structure
© 2014 Pearson Education, Inc.
Figure 34.29a
Finger 1
(b) Bone structure
Palm
(a) Wing
Finger 2
Finger 3
Forearm
Shaft
Vane
Wrist
Shaft
Barb
Barbule
Hook
(c) Feather structure
© 2014 Pearson Education, Inc.
Figure 34.29c
(b) Bone structure
© 2014 Pearson Education, Inc.
Video: Flapping Geese
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Video: Soaring Hawk
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Video: Swans Taking Flight
© 2014 Pearson Education, Inc.
 Flight enhances hunting and scavenging, escape
from terrestrial predators, and migration
 Flight requires a great expenditure of energy,
acute vision, and fine muscle control
© 2014 Pearson Education, Inc.
The Origin of Birds
 Birds probably descended from small theropods, a
group of carnivorous dinosaurs
 Early feathers might have evolved for insulation,
camouflage, or courtship display
© 2014 Pearson Education, Inc.
 By 160 million years ago, feathered theropods had
evolved into birds
 Archaeopteryx remains the oldest bird known
© 2014 Pearson Education, Inc.
Figure 34.30
Was Archaeopteryx the first bird?
Toothed beak
Airfoil wing
with contour
feathers
© 2014 Pearson Education, Inc.
Long tail with
many vertebrae
Wing claw
Living Birds
 Living birds belong to the clade Neornithes
 Several groups of birds are flightless
 The ratites, order Struthioniformes
 Penguins, order Sphenisciformes
 Certain species of rails, ducks, and pigeons
© 2014 Pearson Education, Inc.
Figure 34.31
An emu (Dromaius novaehollandiae), a flightless bird
native to Australia
© 2014 Pearson Education, Inc.
Figure 34.32
A king penguin (Aptenodytes patagonicus) “flying” underwater
© 2014 Pearson Education, Inc.
 The demands of flight have rendered the general
body form of many flying birds similar to one
another
 Bird species can be distinguished by characters
including profile, color, flying style, behavior, beak
shape, and foot structure
© 2014 Pearson Education, Inc.
Figure 34.33
Hummingbird feeding while hovering
© 2014 Pearson Education, Inc.
Figure 34.34
A specialized beak
© 2014 Pearson Education, Inc.
Figure 34.34a
A specialized beak (part 1: greater flamingo)
© 2014 Pearson Education, Inc.
Figure 34.34b
(part 2: greater flamingo beak)
© 2014 Pearson Education, Inc.
Figure 34.35
Feet adapted to perching
© 2014 Pearson Education, Inc.
The Mammals
1.
The following characteristics distinguish mammals:
a.
Hair
i.
Hair provides insulation against heat loss.
ii.
Hair color can provide camouflage to blend into its surroundings.
iii.
Hair can serve sensory functions.
b.
Mammary glands
i.
Mammary glands enable females to feed young without deserting
them to obtain food.
ii.
Nursing creates a bond between mother and offspring to ensure
parental care while the young are helpless.
c.
Skeleton
i.
The mammal skull accommodates a larger brain relative
to body size compared to reptiles’.
ii.
Their teeth are differentiated into molars and premolars.
iii.
The vertebral column provides more movement.
d.
Internal organs
i.
Gas exchange is efficiently accomplished by lungs.
ii.
Mammals possess a four-chambered heart and a double-loop
circulatory system.
iii.
Kidneys are adapted to conserving water.
iv.
The nervous system and sensory organs are highly developed.
e.
Internal development
i.
In most mammals, the young are born alive after a period of
development in the uterus.
© 2014 Pearson Education, Inc.
Concept 34.6: Mammals are amniotes that have
hair and produce milk
 Mammals, class Mammalia, are represented by
more than 5,300 species
© 2014 Pearson Education, Inc.
Figure 34.UN08
Mammalia mini-tree
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
© 2014 Pearson Education, Inc.
Derived Characters of Mammals
 Mammals have
 Mammary glands, which produce milk
 Hair
 A high metabolic rate, due to endothermy
 A larger brain than other vertebrates of equivalent
size
 Differentiated teeth
© 2014 Pearson Education, Inc.
A.
Evolution of Mammals
1.
Mammals evolved during the Mesozoic Era from
mammal-like synapsids.
2.
True mammals appeared during the Triassic period,
about the same time as the first dinosaurs.
a.
The first mammals were small, about the size
of mice.
b.
Some of the earliest mammalian groups were
monotremes and marsupials.
c.
Placental mammals evolved later to occupy
habitats vacated by dinosaurs.
3.
Monotremes
a.
Monotremes are mammals that have a cloaca and lay hardshelled amniote eggs.
b.
They are represented by the duckbill platypus and two species of
the spiny anteaters.
c.
A female duckbill platypus lays her eggs in a burrow in the ground
where she incubates them.
d.
After hatching, the young lick milk seeping from modified sweat
glands on the abdomen.
e.
The spiny anteater has a pouch formed by swollen mammary
glands and muscle; the egg moves from cloaca to pouch and hatches; the
young remain for 53 days and live in the burrow where the mother feeds
them.
© 2014 Pearson Education, Inc.
Early Evolution of Mammals
 Mammals are synapsids
 In the evolution of mammals from early synapsids,
two bones that formerly made up the jaw joint
were incorporated into the mammalian middle ear
© 2014 Pearson Education, Inc.
Figure 34.36
Biarmosuchus,
an extinct
synapsid
The evolution of the mammalian ear bones
Key
Articular
Quadrate
Dentary
Squamosal
Temporal
fenestra
Jaw joint
(a) Articular and quadrate bones in the jaw
Middle ear
Eardrum
Stapes Inner ear
Eardrum Middle ear
Inner ear
Stapes
Sound
Sound
Incus (quadrate)
Malleus
(articular)
Present-day reptile
Present-day mammal
(b) Articular and quadrate bones in the middle ear
© 2014 Pearson Education, Inc.
 By the early Cretaceous, the three living lineages
of mammals emerged: monotremes, marsupials,
and eutherians
 Mammals did not undergo a significant adaptive
radiation until after the Cretaceous
© 2014 Pearson Education, Inc.
Monotremes
 Monotremes are a small group of egg-laying
mammals consisting of echidnas and the platypus
© 2014 Pearson Education, Inc.
Figure 34.37
Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme
© 2014 Pearson Education, Inc.
Figure 34.37a
© 2014 Pearson Education, Inc.
Figure 34.37b
© 2014 Pearson Education, Inc.
4.
Marsupials
a.
Marsupials begin development inside the mother’s
body but are then born in a very immature state.
b.
The newborns crawl up into a pouch on their mother’s abdomen.
c.
Inside a pouch they attach to the nipples of the
mother’s mammary glands and continue to develop.
d.
Today, most marsupials are found in Australia where they underwent
adaptive radiation for several million years without competition from the placental
mammals, only introduced recently.
5.
Placental Mammals
* Developing placental mammals are dependent on a placenta, an organ of
exchange between maternal and fetal blood.
* The placenta supplies nutrients to and removes wastes from the blood of
developing offspring.
* A placenta also allows a mother to move about while the offspring develop.
* The placenta enables young to be born in a relatively advanced stage of
development.
* Placental mammals are very active animals; they possess acute senses and a
relatively large brain.
* The brains of placental animals have cerebral hemispheres proportionately larger
than other animals.
* The young go through a long period of dependency on their parents after birth.
Most are terrestrial, but some are aquatic, and bats can fly.
© 2014 Pearson Education, Inc.
Marsupials
 Marsupials include opossums, kangaroos, and
koalas
 The embryo develops within a placenta in the
mother’s uterus
 A marsupial is born very early in its development
 It completes its embryonic development while
nursing in a maternal pouch called a marsupium
© 2014 Pearson Education, Inc.
Australian marsupials
Figure 34.38
(a) A young brushtail possum
(b) A greater bilby
© 2014 Pearson Education, Inc.
Figure 34.38a
(a) A young brushtail possum
© 2014 Pearson Education, Inc.
Figure 34.38b
(b) A greater bilby
© 2014 Pearson Education, Inc.
 In some species, such as the bandicoot, the
marsupium opens to the rear of the mother’s body
 In Australia, convergent evolution has resulted in a
diversity of marsupials that resemble the
eutherians in other parts of the world
© 2014 Pearson Education, Inc.
Figure 34.39
Convergent evolution of marsupials and
eutherians (placental mammals)
Marsupial mammals Eutherian mammals
© 2014 Pearson Education, Inc.
Plantigale
Deer mouse
Marsupial
mole
Mole
Sugar
glider
Wombat
Tasmanian
devil
Kangaroo
Flying
squirrel
Woodchuck
Wolverine
Patagonian
cavy
Figure 34.39a
Marsupial mammals
Eutherian mammals
Plantigale
Deer mouse
Marsupial
mole
Mole
Sugar
glider
© 2014 Pearson Education, Inc.
Flying
squirrel
Figure 34.39b
Marsupial mammals
Wombat
Tasmanian
devil
Kangaroo
© 2014 Pearson Education, Inc.
Eutherian mammals
Woodchuck
Wolverine
Patagonian
cavy
Eutherians (Placental Mammals)
 Compared with marsupials, eutherians have a
more complex placenta
 Young eutherians complete their embryonic
development within a uterus, joined to the mother
by the placenta
 Molecular and morphological data give conflicting
dates on the diversification of eutherians
© 2014 Pearson Education, Inc.
Figure 34.40a
Monotremes
(5 species)
Marsupials
(324 species)
ANCESTRAL
MAMMAL
Monotremata
Marsupialia
Eutherians
(5,010 species)
Exploring mammalian
diversity (part 1: phylogenetic tree)
© 2014 Pearson Education, Inc.
Proboscidea
Sirenia
Tubulidentata
Hyracoidea
Afrosoricida
Macroscelidea
Xenarthra
Rodentia
Lagomorpha
Primates
Dermoptera
Scandentia
Carnivora
Cetartiodactyla
Perissodactyla
Chiroptera
Eulipotyphla
Pholidota
Figure 34.40aa
Monotremes
(5 species)
Marsupials
(324 species)
ANCESTRAL
MAMMAL
Eutherians
(5,010 species)
© 2014 Pearson Education, Inc.
Monotremata
Marsupialia
Proboscidea
Sirenia
Tubulidentata
Hyracoidea
Afrosoricida
Macroscelidea
Figure 34.40ab
Exploring mammalian diversity (part 1b: phylogenetic tree
Eutherians
(5,010 species)
Proboscidea
Sirenia
Tubulidentata
Hyracoidea
Afrosoricida
Macroscelidea
Xenarthra
Rodentia
Lagomorpha
Primates
Dermoptera
Scandentia
Carnivora
Cetartiodactyla
Perissodactyla
Chiroptera
Eulipotyphla
Pholidota
© 2014 Pearson Education, Inc.
Figure 34.40b
Orders
and Examples
Monotremata
Main
Characteristics
Lay eggs; no nipples;
young suck milk from
fur of mother
Platypuses,
echidnas
Orders
and Examples
Marsupialia
Completes embryonic
development in pouch
on mother’s body
Kangaroos,
opossums,
koalas
Koala
Echidna
Proboscidea
Long, muscular trunk;
thick, loose skin; upper
incisors elongated
as tusks
Elephants
Tubulidentata
Teeth consisting of
many thin tubes
cemented together;
eats ants and termites
Aardvarks
African elephant
Sirenia
Aardvark
Aquatic; finlike forelimbs and no hind
limbs; herbivorous
Manatees,
dugongs
Hyracoidea
Short legs; stumpy
tail; herbivorous;
complex, multichambered stomach
Hyraxes
Manatee
Xenarthra
Rock hyrax
Reduced teeth or no
teeth; herbivorous
(sloths) or carnivorous
(anteaters, armadillos)
Sloths,
anteaters,
armadillos
Tamandua
Lagomorpha
Rabbits, hares,
picas
Rodentia
Dogs, wolves,
bears, cats,
weasels, otters,
seals, walruses
Artiodactyls:
sheep, pigs,
cattle, deer,
giraffes
Primates
Sharp, pointed canine
teeth and molars for
shearing; carnivorous
Perissodactyla
Opposable thumbs;
forward-facing eyes;
well-developed cerebral
cortex; omnivorous
Lemurs, monkeys,
chimpanzees,
gorillas, humans
Golden lion
tamarin
Hooves with an odd
number of toes on
each foot; herbivorous
Horses,
zebras, tapirs,
rhinoceroses
Indian rhinoceros
Hooves with an even
number of toes on each
foot; herbivorous
Chiroptera
Bats
Frog-eating bat
Bighorn sheep
Cetaceans:
whales,
dolphins,
porpoises
Pacific whitesided porpoise
© 2014 Pearson Education, Inc.
Red squirrel
Chisel-like incisors;
hind legs longer than
forelegs and adapted
for running and jumping; herbivorous
Coyote
Cetartiodactyla
Chisel-like, continuously
growing incisors worn
down by gnawing;
herbivorous
Squirrels,
beavers, rats,
porcupines,
mice
Jackrabbit
Carnivora
Main
Characteristics
Aquatic; streamlined
body; paddle-like
forelimbs and no hind
limbs; thick layer of
insulating blubber;
carnivorous
Eulipotyphla
“Core
insectivores”:
some moles,
some shrews
Adapted for flight;
broad skinfold that
extends from elongated
fingers to body and
legs; carnivorous or
herbivorous
Eat mainly insects
and other small
invertebrates
Star-nosed
mole
Figure 34.40ba
Orders and Examples
Main Characteristics
Lay eggs; no nipples;
young suck milk from
fur of mother
Monotremata
Platypuses,
echidnas
Echidna
Marsupialia
Kangaroos,
opossums,
koalas
Completes embryonic
development in pouch
on mother’s body
Koala
© 2014 Pearson Education, Inc.
Figure 34.40bb
Orders and Examples
Main Characteristics
Long, muscular trunk;
thick, loose skin; upper
incisors elongated
as tusks
Proboscidea
Elephants
African elephant
Aquatic; finlike forelimbs and no hind
limbs; herbivorous
Sirenia
Manatees,
dugongs
Manatee
Teeth consisting of
many thin tubes
cemented together;
eats ants and termites
Tubulidentata
Aardvarks
Aardvark
Hyracoidea
Hyraxes
Rock hyrax
© 2014 Pearson Education, Inc.
Short legs; stumpy
tail; herbivorous;
complex, multichambered stomach
Figure 34.40bc
Orders and Examples
Xenarthra
Sloths,
anteaters,
armadillos
Tamandua
Lagomorpha
Rabbits, hares,
picas
Jackrabbit
Main Characteristics
Reduced teeth or no
teeth; herbivorous
(sloths) or carnivorous
(anteaters, armadillos)
Chisel-like incisors;
hind legs longer than
forelegs and adapted
for running and jumping; herbivorous
Rodentia
Squirrels,
beavers,
rats, porcupines,
mice
Red squirrel
Chisel-like, continuously
growing incisors worn
down by gnawing;
herbivorous
Primates
Lemurs, monkeys,
chimpanzees,
gorillas, humans
Golden lion
tamarin
Opposable thumbs;
forward-facing eyes;
well-developed cerebral
cortex; omnivorous
© 2014 Pearson Education, Inc.
Figure 34.40bd
Orders and Examples
Carnivora
Dogs, wolves,
bears, cats,
weasels, otters,
seals, walruses
Main Characteristics
Sharp, pointed canine
teeth and molars for
shearing; carnivorous
Coyote
Cetartiodactyla
Hooves with an even
Artiodactyls:
number of toes on each
sheep, pigs,
foot; herbivorous
cattle, deer,
Bighorn sheep
giraffes
Aquatic; streamlined
Cetaceans:
body; paddle-like
whales,
forelimbs and no hind
dolphins,
limbs; thick layer of
porpoises Pacific whiteinsulating blubber;
sided porpoise carnivorous
© 2014 Pearson Education, Inc.
Figure 34.40be
Orders and Examples
Main Characteristics
Perissodactyla
Hooves with an odd
Horses, zebras,
number of toes on
tapirs,
each foot; herbivorous
rhinoceroses
Indian
rhinoceros
Chiroptera
Bats
Adapted for flight;
broad skinfold that
extends from elongated
fingers to body and
Frog-eating bat legs; carnivorous or
herbivorous
Eulipotyphla
“Core
insectivores”:
some moles,
some shrews
© 2014 Pearson Education, Inc.
Eat mainly insects
and other small
invertebrates
Star-nosed
mole
Video: Bat Licking Nectar
© 2014 Pearson Education, Inc.
Video: Bat Pollinating Agave Plant
© 2014 Pearson Education, Inc.
Video: Galápagos Sea Lion
© 2014 Pearson Education, Inc.
Video: Wolves Agonistic Behavior
© 2014 Pearson Education, Inc.
Video: Shark Eating a Seal
© 2014 Pearson Education, Inc.
Primates
 The mammalian order Primates includes lemurs,
tarsiers, monkeys, and apes
 Humans are members of the ape group
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Derived Characters of Primates
 Most primates have hands and feet adapted for
grasping, and flat nails
© 2014 Pearson Education, Inc.
 Other derived characters of primates
 A large brain and short jaws
 Forward-looking eyes close together on the face,
providing depth perception
 Complex social behavior and parental care
 A fully opposable thumb (in monkeys and apes)
© 2014 Pearson Education, Inc.
Living Primates
 There are three main groups of living primates
 Lemurs, lorises, and bush babies
 Tarsiers
 Anthropoids (monkeys and apes)
© 2014 Pearson Education, Inc.
Verreaux’s sifakas (Propithecus verreauxi),
a type of lemur
Figure 34.41
© 2014 Pearson Education, Inc.
 The oldest known anthropoid fossils, about 45
million years old, indicate that tarsiers are more
closely related to anthropoids than to lemurs
© 2014 Pearson Education, Inc.
Figure 34.42
Lemurs, lorises,
and bush babies
ANCESTRAL
PRIMATE
New World monkeys
Old World monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees
and bonobos
Humans
70
60 50 40 30 20 10
Time (millions of years ago)
© 2014 Pearson Education, Inc.
0
Anthropoids
A phylogenetic tree of primates
Tarsiers
 The first monkeys evolved in the Old World (Africa
and Asia)
 In the New World (South America), monkeys first
appeared roughly 25 million years ago
 New World and Old World monkeys underwent
separate adaptive radiations during their many
millions of years of separation
© 2014 Pearson Education, Inc.
Figure 34.43
(a) New World monkey:
spider monkey
(b) Old World monkey:
macaque
© 2014 Pearson Education, Inc.
 The other group of anthropoids consists of
primates informally called apes
 This group includes gibbons, orangutans, gorillas,
chimpanzees, bonobos, and humans
 Apes diverged from Old World monkeys about 25–
30 million years ago
© 2014 Pearson Education, Inc.
Figure 34.44
Nonhuman apes
(a) Gibbon
(b) Orangutan
(c) Gorilla
(d) Chimpanzees
© 2014 Pearson Education, Inc.
(e) Bonobos
Video: Chimp Cracking Nut
© 2014 Pearson Education, Inc.
Concept 34.7: Humans are mammals that have a
large brain and bipedal locomotion
 The species Homo sapiens is about 200,000 years
old, which is very young, considering that life has
existed on Earth for at least 3.5 billion years
© 2014 Pearson Education, Inc.
Derived Characters of Humans
 A number of characters distinguish humans from
other apes
 Upright posture and bipedal locomotion
 Larger brains capable of language, symbolic
thought, artistic expression, the manufacture and
use of complex tools
 Reduced jawbones and jaw muscles
 Shorter digestive tract
© 2014 Pearson Education, Inc.
 The human and chimpanzee genomes are 99%
identical
 Changes in regulatory genes can have large
effects
© 2014 Pearson Education, Inc.
The Earliest Hominins
 The study of human origins is known as
paleoanthropology
 Hominins (formerly called hominids) are more
closely related to humans than to chimpanzees
 Paleoanthropologists have discovered fossils of
about 20 species of extinct hominins
© 2014 Pearson Education, Inc.
Figure 34.45
A timeline for selected hominin species
Paranthropus
robustus
0
Homo
ergaster
Paranthropus
boisei
0.5
Homo
Homo
neanderthalensis sapiens
?
1.0
Australopithecus
africanus
1.5
Millions of years ago
2.0
2.5
Kenyanthropus
platyops
Australopithecus
garhi
Australo3.0 pithecus
anamensis
3.5
Homo
habilis
4.0
4.5
Australopithecus
afarensis
5.0
Ardipithecus ramidus
5.5
6.0
Homo erectus
Orrorin tugenensis
6.5
7.0
© 2014 Pearson Education, Inc.
Sahelanthropus
tchadensis
Homo
rudolfensis
Figure 34.45a
Homo
neander- Homo
thalensis sapiens
Paranthropus Homo
robustus
ergaster
Millions of years ago
0
0.5
?
Paranthropus
boisei
1.0
1.5
2.0
2.5
Australopithecus
garhi
3.0
Australopithecus
3.5 africanus
Homo erectus
Homo
habilis
© 2014 Pearson Education, Inc.
Homo
rudolfensis
Figure 34.45b
Millions of years ago
Kenyanthropus
platyops
2.5 Australopithecus
3.0 anamensis
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
© 2014 Pearson Education, Inc.
Australopithecus
afarensis
Ardipithecus ramidus
Orrorin tugenensis
Sahelanthropus
tchadensis
 The oldest fossil evidence of hominins dates back
to 6.5 million years ago
 Early hominins show evidence of small brains and
increasing bipedalism
© 2014 Pearson Education, Inc.
Figure 34.46
© 2014 Pearson Education, Inc.
 Misconception: Early hominins were chimpanzees
 Correction: Hominins and chimpanzees shared a
common ancestor
 Misconception: Human evolution is like a ladder
leading directly to Homo sapiens
 Correction: Hominin evolution included many
branches or coexisting species, though only
humans survive today
© 2014 Pearson Education, Inc.
Figure 34.47
Evidence that hominins walked upright 3.5 million years ago
(a) The Laetoli footprints
© 2014 Pearson Education, Inc.
(b) An artist’s reconstruction of A. afarensis
 “Robust” australopiths had sturdy skulls and
powerful jaws
 “Gracile” australopiths were more slender and had
lighter jaws
© 2014 Pearson Education, Inc.
Bipedalism
 Hominins began to walk long distances on two
legs about 1.9 million years ago
 Bipedal walking was energy efficient in the arid
environments inhabited by hominins at the time
© 2014 Pearson Education, Inc.
Tool Use
 The oldest evidence of tool use, cut marks on
animal bones, is 2.5 million years old
 Fossil evidence indicates tool use may have
originated prior to the evolution of large brains
© 2014 Pearson Education, Inc.
Early Homo
 The earliest fossils placed in our genus Homo are
those of Homo habilis, ranging in age from about
2.4 to 1.6 million years
 Stone tools have been found with H. habilis, giving
this species its name, which means “handy man”
© 2014 Pearson Education, Inc.
 Homo ergaster was the first fully bipedal, largebrained hominid
 The species existed between 1.9 and 1.5 million
years ago
 Homo ergaster shows a significant decrease in
sexual dimorphism (a size difference between
sexes) compared with its ancestors
© 2014 Pearson Education, Inc.
 Homo ergaster fossils were previously assigned to
Homo erectus; most paleoanthropologists now
recognize these as separate species
© 2014 Pearson Education, Inc.
 Homo erectus originated in Africa by 1.8 million
years ago
 It was the first hominin to leave Africa
© 2014 Pearson Education, Inc.
Neanderthals
 Neanderthals, Homo neanderthalensis, lived in
Europe and the Near East from 350,000 to 28,000
years ago
 They were thick-boned with a larger brain, they
buried their dead, and they made hunting tools
 Recent genetic analysis indicates that gene flow
occurred between Neanderthals and Homo
sapiens
© 2014 Pearson Education, Inc.
Homo Sapiens
 Homo sapiens appeared in Africa by 195,000
years ago
 All living humans are descended from these
African ancestors
© 2014 Pearson Education, Inc.
Figure 34.UN10
Homo sapiens skull fossil,
A 160,000-year-old fossil of
Homo sapiens.
© 2014 Pearson Education, Inc.
 The oldest fossils of Homo sapiens outside Africa
date back about 115,000 years and are from the
Middle East
 Humans first arrived in the New World sometime
before 15,000 years ago
 In 2004, 18,000-year-old fossils were found in
Indonesia, and a new small hominin was named:
Homo floresiensis
© 2014 Pearson Education, Inc.
 Homo sapiens were the first group to show
evidence of symbolic and sophisticated thought
 In 2002, a 77,000-year-old artistic carving was
found in South Africa
© 2014 Pearson Education, Inc.
B.
Vertebrates and Human Medicine (Nature of Science reading)
1.
There are many pharmaceutical products that come from vertebrates.
a.
The venom of the Thailand cobra is the source of Immunokine, which has
been used for ten years in multiple sclerosis patients.
b.
ABT-594 from the poison dart frog is about 50 times more powerful than
morphine without the addictive properties.
2.
Animal pharming uses genetically altered vertebrates (mice, sheep, goats,
cows, chickens, pigs) to produce medically useful pharmaceutical products.
a.
The human gene for some useful product is inserted into the embryo of the
vertebrate.
b.
That embryo is implanted into a foster mother, which gives birth to the
transgenic animal.
3.
Xenotransplantation is the transplantation of nonhuman vertebrate tissues
and organs into humans.
a.
The use of transgenic vertebrates for medical
purposes raises many health and ethical concerns.
© 2014 Pearson Education, Inc.
Figure 34.50
© 2014 Pearson Education, Inc.
Figure 34.UN11
Urochordata
(tunicates)
Marine suspension feeders; larvae display the
derived traits of chordates
Myxini (hagfishes)
Jawless marine vertebrates with reduced vertebrae;
have head that includes a skull and brain, eyes, and
other sensory organs
Jawless aquatic vertebrates with reduced
vertebrae; typically feed by attaching to a live
fish and ingesting its blood
Aquatic gnathostomes; have cartilaginous skeleton,
a derived trait formed by the reduction of an
ancestral mineralized skeleton
Aquatic gnathostomes; have bony skeleton and
maneuverable fins supported by rays
Chondrichthyes
(sharks, rays,
skates, ratfishes)
Actinopterygii
(ray-finned fishes)
Amniotes: amniotic egg,
rib cage ventilation
Dipnoi
(lungfishes)
Tetrapods: four limbs, neck,
fused pelvic girdle
Lobe-fins: muscular fins or limbs
Osteichthyans: bony skeleton
Actinistia
(coelacanths)
© 2014 Pearson Education, Inc.
Description
Basal chordates; marine suspension feeders that
exhibit four key derived characters of chordates
Petromyzontida
(lampreys)
Gnathostomes: hinged jaws, four sets of Hox genes
Vertebrates: Hox genes duplication, backbone of vertebrae
Chordates: notochord; dorsal, hollow nerve cord; pharyngeal slits; post-anal tail
Clade
Cephalochordata
(lancelets)
Ancient lineage of aquatic lobe-fins still surviving
in Indian Ocean
Freshwater lobe-fins with both lungs and gills;
sister group of tetrapods
Amphibia
(salamanders,
frogs, caecilians)
Reptilia (tuataras, lizards
and snakes, turtles,
crocodilians,
birds)
Have four limbs descended from modified fins; most
have moist skin that functions in gas exchange; many
live both in water (as larvae) and on land (as adults)
One of two groups of living amniotes; have amniotic
eggs and rib cage ventilation, key adaptations for life
on land
Mammalia
(monotremes,
marsupials,
eutherians)
Evolved from synapsid ancestors; include egg-laying
monotremes (echidnas, platypus); pouched marsupials
(such as kangaroos, opossums); and eutherians
(placental mammals, such as rodents, primates)
Figure 34.UN11a
Clade
Description
Cephalochordata
(lancelets)
Basal chordates; marine suspension feeders that
exhibit four key derived characters of chordates
Urochordata
(tunicates)
Marine suspension feeders; larvae display the
derived traits of chordates
Myxini (hagfishes)
Chondrichthyes
(sharks, rays,
skates, ratfishes)
Actinopterygii
(ray-finned fishes)
Jawless marine vertebrates with reduced vertebrae;
have head that includes a skull and brain, eyes, and
other sensory organs
Jawless aquatic vertebrates with reduced
vertebrae; typically feed by attaching to a live
fish and ingesting its blood
Aquatic gnathostomes; have cartilaginous skeleton,
a derived trait formed by the reduction of an
ancestral mineralized skeleton
Aquatic gnathostomes; have bony skeleton and
maneuverable fins supported by rays
Actinistia
(coelacanths)
Ancient lineage of aquatic lobe-fins still surviving
in Indian Ocean
Dipnoi
(lungfishes)
Freshwater lobe-fins with both lungs and gills;
sister group of tetrapods
Petromyzontida
(lampreys)
© 2014 Pearson Education, Inc.