1. Chapter 34
Vertebrates

2. The animals called vertebrates
Overview:
The animals called vertebrates
Get their name from vertebrae, the series of bones that make up the backbone
Figure 34.1

3. Concept 34.1: Derived Characters of Chordates
All chordates share a set of derived characters
Although some species possess some of these traits only during embryonic development
Muscle segments
Brain
Mouth
Anus
Dorsal, hollow nerve cord
Notochord
Muscular, post-anal tail
Pharyngeal slits or clefts
Figure 34.3

4. In most vertebrates, a more complex, jointed skeleton develops
Notochord
The notochord
Is a longitudinal, flexible rod located between the digestive tube and the nerve cord
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

5. 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
Develops into the central nervous system: the brain and the spinal cord

6. 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
These pharyngeal slits
Are modified for gas exchange in aquatic vertebrates
Develop into parts of the ear, head, and neck in terrestrial vertebrates

7. Muscular, Post-Anal Tail
Chordates have a tail extending posterior to the anus
Although in many species it is lost during embryonic development
The chordate tail contains skeletal elements and muscles
And it provides much of the propelling force in many aquatic species

8. Craniates are chordates that have a head The origin of a head
Concept 34.2:
Craniates are chordates that have a head
The origin of a head
Opened up a completely new way of feeding for chordates: active predation
Craniates share some common characteristics
A skull, brain, eyes, and other sensory organs

9. Vertebrates are craniates that have a backbone
Concept 34.3:
Vertebrates are craniates that have a backbone
Vertebrates have
Vertebrae enclosing a spinal cord
An elaborate skull
Fin rays, in aquatic forms

10. Lampreys, class Cephalaspidomorphi
Represent the oldest living lineage of vertebrates
Have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

11. Lampreys are jawless vertebrates
Inhabiting various marine and freshwater habitats
Figure 34.10

12. Gnathostomes are vertebrates that have jaws Today, jawless vertebrates
Concept 34.4:
Gnathostomes are vertebrates that have jaws
Today, jawless vertebrates
Are far outnumbered by those with jaws

13. Other characters common to gnathostomes include
Enhanced sensory systems, including the lateral line system
An extensively mineralized endoskeleton
Paired appendages

14. Chondrichthyans (Sharks, Rays, and Their Relatives)
Members of class Chondrichthyes
Have a skeleton that is composed primarily of cartilage
The cartilaginous skeleton
Evolved secondarily from an ancestral mineralized skeleton

15. The largest and most diverse subclass of Chondrichthyes
Includes the sharks and rays
Figure 34.15a, b
Pectoral fins
Pelvic fins
(a) Blacktip reef shark (Carcharhinus melanopterus). Fast swimmers with acute senses, sharks have paired pectoral and pelvic fins.
(b) Southern stingray (Dasyatis americana). Most rays are flattened bottom-dwellers that crush molluscs and crustaceans for food. Some rays cruise in open water and scoop food into their gaping mouth.

16. Ray-Finned Fishes and Lobe-Fins
The vast majority of vertebrates
Belong to a clade of gnathostomes called Osteichthyes

17. Nearly all living osteichthyans
Have a bony endoskeleton
Aquatic osteichthyans
Are the vertebrates we informally call fishes
Control their buoyancy with an air sac known as a swim bladder

18. Fishes breathe by drawing water over four or five pairs of gills
Nostril
Brain
Spinal cord
Swim bladder
Dorsal fin
Adipose fin (characteristic of trout)
Caudal fin
Cut edge of operculum
Gills
Heart
Liver
Kidney
Stomach
Intestine
Gonad
Anus
Urinary bladder
Lateral line
Anal fin
Pelvic fin
Figure 34.16

19. Ray-Finned Fishes
The ray-finned fishes includes nearly all the familiar aquatic osteichthyans
(a) Yellowfin tuna (Thunnus albacares), a fast-swimming, schooling fish that is an important commercial fish worldwide
(b) Clownfish (Amphiprion ocellaris), a mutualistic symbiont of sea anemones
(c) Sea horse (Hippocampus ramulosus), unusual in the animal kingdom in that the male carries the young during their embryonic development
(d) Fine-spotted moray eel (Gymnothorax dovii), a predator that ambushes prey from crevices in its coral reef habitat
Figure 34.17a–d

20. The fins, supported mainly by long, flexible rays
Are modified for maneuvering, defense, and other functions

21. Lobe-Fins The lobe-fins
Have muscle covering bones of their pelvic and pectoral fins
Include coelacanths, lungfishes, and tetrapods
Figure 34.18

22. Tetrapods are gnathostomes that have limbs and feet
Concept 34.5:
Tetrapods are gnathostomes that have limbs and feet
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

23. Derived Characters of Tetrapods
Tetrapods have some specific adaptations
Four limbs and feet with digits
Ears for detecting airborne sounds

24. Amphibians are represented by about 4,800 species of organisms
Most amphibians
Have moist skin that complements the lungs in gas exchange

25. Includes salamanders, which have tails
Amphibians
Includes salamanders, which have tails
Figure 34.21a
(a) salamanders retain their tail as adults.

26. Includes frogs and toads, which lack tails as adults
Amphibians
Includes frogs and toads, which lack tails as adults
Figure 34.21b
(b) poison arrow frog

27. Includes caecilians, which are legless and resemble worms
Amphibians
Includes caecilians, which are legless and resemble worms
Figure 34.21c
(c) Caecilians, mainly burrowing amphibians.

28. Amphibian means “two lives”
Amphibians
Amphibian means “two lives”
A reference to the metamorphosis of an aquatic larva into a terrestrial adult
Figure 34.22a–c
(a) The male grasps the female, stimulating her to release eggs. The eggs are laid and fertilized in water. They have a jelly coat but lack a shell and would desiccate in air.
(b) The tadpole is an aquatic herbivore with a fishlike tail and internal gills.
(c) During metamorphosis, the gills and tail are resorbed, and walking legs develop.

29. Amniotes are tetrapods that have a terrestrially adapted egg
Concept 34.6:
Amniotes are tetrapods that have a terrestrially adapted egg
Amniotes are a group of tetrapods
Whose living members are the reptiles, including birds, and the mammals

30. Derived Characters of Amniotes
Amniotes are named for the major derived character of the clade, the amniotic egg
Which contains specialized membranes that protect the embryo

31. Extraembryonic membranes
The extraembryonic membranes have various functions
Figure 34.24
Shell
Albumen
Yolk (nutrients)
Amniotic cavity with amniotic fluid
Embryo
Yolk sac. The yolk sac contains the yolk, a stockpile of nutrients. Blood vessels in the yolk sac membrane transport nutrients from the yolk into the embryo. Other nutrients are stored in the albumen (“egg white”).
Allantois. The allantois is a disposal
sac for certain metabolic wastes pro-
duced by the embryo. The membrane
of the allantois also functions with
the chorion as a respiratory organ.
Amnion. The amnion protects the embryo in a fluid-filled cavity that cushions against mechanical shock.
Chorion. The chorion and the membrane of the allantois exchange gases between the embryo and the air. Oxygen and carbon dioxide diffuse freely across the shell.
Extraembryonic membranes

32. Amniotes also have other terrestrial adaptations
Such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs

33. The reptile clade includes
Reptiles
The reptile clade includes
The tuatara, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs

34. Reptiles Have scales that create a waterproof barrier
Lay shelled eggs on land
Figure 34.25

35. Most reptiles are ectothermic
Absorbing external heat as the main source of body heat
Birds are endothermic
Capable of keeping the body warm through metabolism

36. The Origin and Evolutionary Radiation of Reptiles
One surviving lineage of lepidosaurs
Is represented by two species of lizard-like reptiles called tuatara
Figure 34.27a
(a) Tuatara (Sphenodon punctatus)

37. The other major living lineage of lepidosaurs
Are the squamates, the lizards and snakes
Lizards
Are the most numerous and diverse reptiles, apart from birds
Figure 34.27b
(b) Australian thorny devil lizard (Moloch horridus)

38. (c) Wagler’s pit viper (Tropidolaemus wagleri), a snake
Snakes are legless lepidosaurs
That evolved from lizards
Figure 34.27c
(c) Wagler’s pit viper (Tropidolaemus wagleri), a snake

39. Some turtles have adapted to deserts
Are the most distinctive group of reptiles alive today
Some turtles have adapted to deserts
And others live entirely in ponds and rivers

40. (d) Eastern box turtle (Terrapene carolina carolina)
All turtles have a boxlike shell
Made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs
Figure 34.27d
(d) Eastern box turtle (Terrapene carolina carolina)

41. Alligators and Crocodiles
Crocodilians
Belong to a lineage that dates back about 200 million years
Figure 34.27e
(e) American alligator (Alligator mississipiensis)

42. Birds Birds are archosaurs
But almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight

43. Derived Characters of Birds
A bird’s most obvious adaptations for flight
Are its wings and feathers
Figure 34.28a–c
(a) wing
(b) Bone structure
Finger 1
(c) Feather structure
Shaft
Barb
Barbule
Hook
Vane
Forearm
Wrist
Palm
Finger 3
Finger 2

44. (a) Emu. This ratite lives in Australia.
Living Birds
The ratites, order Struthioniformes
Are all flightless
Figure 34.30a
(a) Emu. This ratite lives in Australia.

45. The demands of flight
Have rendered the general body form of many flying birds similar to one another
Figure 34.30b–d
(b) Mallards. Like many bird species, the mallard exhibits pronounced color differences between the sexes.
(c) Laysan albatrosses. Like most birds, Laysan albatrosses have specific mating behaviors, such as this courtship ritual.
(d) Barn swallows. The barn swallow is a member of the order Passeriformes. Species in this order are called perching birds because the toes of their feet can lock around a branch or wire, enabling the bird to rest in place for long periods.

46. Foot structure in bird feet
Shows considerable variation
Figure 34.31
Grasping bird (such as a woodpecker)
Perching bird (such as a cardinal)
Raptor (such as a bald eagle)
Swimming bird (such as a duck)

47. Mammals are amniotes that have hair and produce milk
Concept 34.7:
Mammals are amniotes that have hair and produce milk
Mammals, class Mammalia
Are represented by more than 5,000 species

48. Derived Characters of Mammals
Mammary glands, which produce milk are a distinctively mammalian character
Hair is another mammalian characteristic
Mammals generally have a larger brain than other vertebrates of equivalent size

49. Monotremes Monotremes
Are a small group of egg-laying mammals consisting of echidnas and the platypus
Figure 34.33

50. Marsupials
Marsupials
Include opossums, kangaroos, and koalas

51. A marsupial is born very early in its development
And completes its embryonic development while nursing within a maternal pouch called a marsupium
Figure 34.34a
(a) A young brushtail possum.

52. Eutherians (Placental Mammals)
Compared to marsupials
Eutherians have a longer period of pregnancy
Eutherians
Complete their embryonic development within a uterus, joined to the mother by the placenta

53. The major eutherian orders
Figure 34.36
ORDERS
AND EXAMPLES
MAIN CHARACTERISTICS
Monotremata Platypuses, echidnas
Proboscidea Elephants
Sirenia Manatees, dugongs
Cetartiodactyla Artiodactyls Sheep, pigs cattle, deer, giraffes
Lagomorpha Rabbits, hares, picas
Carnivora Dogs, wolves, bears, cats, weasels, otters,
seals, walruses
Xenarthra Sloths, anteaters, armadillos
Cetaceans Whales, dolphins, porpoises
Echidna
African elephant
Manatee
Tamandua
Jackrabbit
Coyote
Bighorn sheep
Pacific white- sided porpoise
Lay eggs; no nipples; young suck milk from fur of mother
Long, muscular trunk; thick, loose skin; upper incisors elongated as tusks
Aquatic; finlike forelimbs and no hind limbs; herbivorous
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
Sharp, pointed canine teeth and molars for shearing; carnivorous
Hooves with an even number of toes on each foot; herbivorous
Aquatic; streamlined body; paddle-like forelimbs and no hind limbs; thick layer of insulating blubber; carnivorous
Diet consists mainly of insects and other small invertebrates
Adapted for flight; broad skinfold that extends from elongated fingers to body and legs; carnivorous or herbivorous
Hooves with an odd number of toes on each foot; herbivorous
Opposable thumbs; forward-facing eyes; well-developed cerebral cortex; omnivorous
Chisel-like, continuously growing incisors worn down by gnawing; herbivorous
Short legs; stumpy tail; herbivorous; complex, multichambered
stomach
Teeth consisting of many thin tubes cemented together; eats ants and termites
Embryo completes development in pouch on mother
Marsupialia
Kangaroos,
opossums,
koalas
Tubulidentata
Aardvark
Hyracoidea
Hyraxes
Chiroptera
Bats
Primates
Lemurs,
monkeys,
apes,
humans
Perissodactyla
Horses,
zebras, tapirs,
rhinoceroses
Rodentia
Squirrels,
beavers, rats,
porcupines,
mice  
Eulipotyphla
“Core insecti-
vores”: some
moles, some
shrews
Star-nosed mole
Frog-eating bat
Indian rhinoceros
Golden lion tamarin
Red squirrel
Rock hyrax
Koala

54. The mammalian order Primates include
Lemurs, tarsiers, monkeys, and apes
Humans are members of the ape group
Figure Lemurs

55. Derived Characters of Primates
Most primates
Have hands and feet adapted for grasping
Primates also have
A large brain and short jaws
Forward-looking eyes close together on the face, providing depth perception
Well-developed parental care and complex social behavior
A fully opposable thumb

56. Hominoids (Apes) Figure 34.40a–e
(a) Gibbons, such as this Muller's gibbon, are found only in southeastern Asia. Their very long arms and fingers are adaptations for brachiation.
(b) Orangutans are shy, solitary apes that live in the rain forests of Sumatra and Borneo. They spend most of their time in trees; note the foot adapted for grasping and the opposable thumb.
(c) Gorillas are the largest apes: some males are almost 2 m tall and weigh about 200 kg. Found only in Africa, these herbivores usually live in groups of up to about 20 individuals.
(d) Chimpanzees live in tropical Africa. They feed and sleep in trees but also spend a great deal of time on the ground. Chimpanzees are intelligent, communicative, and social.
(e) Bonobos are closely related to chimpanzees but are smaller. They survive today only in the African nation of Congo.

57. Concept 34.8:
Humans are bipedal hominoids with a large brain
Homo sapiens is about 160,000 years old

58. Derived Characters of Hominids
A number of characters distinguish humans from other hominoids
Upright posture and bipedal locomotion
Larger brains
Language capabilities
The manufacture and use of complex tools
Shortened jaw

59. The study of human origins
The Earliest Humans
The study of human origins
Is known as paleoanthropology

60. Hominids Figure 34.41 Homo sapiens Homo neanderthalensis Homo ergaster?
Homo erectus
Homo habilis
Homo rudolfensis
Paranthropus robustus
Paranthropus boisei
Australopithecus garhi
Australopithecus africanus
Australopithecus afarensis
Kenyanthropus platyops
Australopithecus anamensis
Ardipithecus ramidus
Orrorin tugenensis
Sahelanthropus tchadensis
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Millions of years ago

61. Hominids originated in Africa
Approximately 6–7 million years ago
Early hominids
Had a small brain, but probably walked upright, exhibiting mosaic evolution

62. The earliest fossils that paleoanthropologists place in our genus Homo
Early Homo
The earliest fossils that paleoanthropologists place in our genus Homo
Are those of the species 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”

63. Homo ergaster Was the first fully bipedal, large-brained hominid
Existed between 1.9 and 1.6 million years
Figure 34.43

64. Homo erectus Originated in Africa approximately 1.8 million years ago
Was the first hominid to leave Africa

65. Neanderthals, Homo neanderthalensis
Lived in Europe and the Near East from 200,000 to 30,000 years ago
Were large, thick-browed hominids
Became extinct a few thousand years after the arrival of Homo sapiens in Europe

66. Homo sapiens Homo sapiens
Appeared in Africa at least 160,000 years ago
Figure 34.44