1. The Origin and Evolution of Vertebrates
Chapter 34
The Origin and Evolution of Vertebrates

2. Birds
Birds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight
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3. 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
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4. Finger 1 (b) Bone structure Palm (a) Wing Finger 2 Forearm Finger 3
Figure 34.30
Finger 1
(b) Bone structure
Palm
(a) Wing
Finger 2
Forearm
Finger 3
Wrist
Figure Form fits function: the avian wing and feather.
Shaft
Shaft
Barb
Vane
Barbule
Hook
(c) Feather structure 4

5. Flight enhances hunting and scavenging, escape from terrestrial predators, and migration
Flight requires a great expenditure of energy, acute vision, and fine muscle control
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6. 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
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7. Early feathers might have helped dinosaurs
Gain lift when they jumped
Gain traction running up hills
Glide from trees
By 150 million years ago, feathered theropods had evolved into birds
Archaeopteryx remains the oldest bird known
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8. Airfoil wing with contour feathers Long tail with many vertebrae
Figure 34.31
Toothed beak
Wing claw
Figure Artist’s reconstruction of Archaeopteryx, the earliest known bird.
Airfoil wing with contour feathers
Long tail with many vertebrae 8

9. The demands of flight have rendered the general body form of many flying birds similar to one another
Video: Flapping Geese
Video: Soaring Hawk
Video: Swans Taking Flight
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10. Figure 34.33
Figure A king penguin (Aptenodytes patagonicus) “flying” underwater. 10

11. Figure 34.34
Figure Hummingbird feeding while hovering. 11

12. Figure 34.35
Figure Specialized beaks. 12

13. Figure 34.36
Figure Feet adapted to perching. 13

14. Concept 34.7: Mammals are amniotes that have hair and produce milk
Mammals, class Mammalia, are represented by more than 5,300 species
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15. 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
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16. Early Evolution of Mammals
Mammals evolved from synapsids
Two bones that formerly made up the jaw joint were incorporated into the mammalian middle ear
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17. Biarmosuchus, a synapsid
Figure 34.37
Biarmosuchus, a synapsid
Key
Temporal fenestra
Articular
Quadrate
Jaw joint
Dentary
Squamosal
(a) Articular and quadrate bones in the jaw
Middle ear
Inner ear
Eardrum
Middle ear
Eardrum
Stapes
Inner ear
Stapes
Figure The evolution of the mammalian ear bones.
Incus (quadrate)
Sound
Sound
Malleus (articular)
Present-day reptile
Present-day mammal
(b) Articular and quadrate bones in the middle ear 17

18. 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
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19. Monotremes
Monotremes are a small group of egg-laying mammals consisting of echidnas and the platypus
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20. Figure 34.38
Figure Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme. 20

21. 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
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22. (a) A young brushtail possum
Figure 34.39
(a) A young brushtail possum
Figure Australian marsupials.
(b) Long-nosed bandicoot 22

23. In Australia, convergent evolution has resulted in a diversity of marsupials that resemble the eutherians in other parts of the world
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24. Figure 34.40
Marsupial mammals
Eutherian mammals
Plantigale
Deer mouse
Marsupial mole
Mole
Sugar glider
Flying squirrel
Wombat
Woodchuck
Wolverine
Figure Convergent evolution of marsupials and eutherians (placental mammals).
Tasmanian devil
Patagonian cavy
Kangaroo 24

25. 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
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26. Figure 34.41 Exploring: Mammalian Diversity.
Figure 34.41b
Orders and Examples
Main Characteristics
Orders and Examples
Main Characteristics
Monotremata
Lay eggs; no nipples; young suck milk from fur of mother
Marsupialia
Completes embryonic development in pouch on mother’s body
Platypuses, echidnas
Kangaroos, opossums, koalas
Echidna
Koala
Proboscidea
Long, muscular trunk; thick, loose skin; upper incisors elongated as tusks
Tubulidentata
Teeth consisting of many thin tubes cemented together; eats ants and termites
Elephants
Aardvarks
African elephant
Aardvark
Sirenia
Aquatic; finlike fore- limbs and no hind limbs; herbivorous
Hyracoidea
Short legs; stumpy tail; herbivorous; complex, multi- chambered stomach
Manatees, dugongs
Hyraxes
Manatee
Rock hyrax
Xenarthra
Reduced teeth or no teeth; herbivorous (sloths) or carnivorous (anteaters, armadillos)
Rodentia
Chisel-like, continuously growing incisors worn down by gnawing; herbivorous
Sloths, anteaters, armadillos
Squirrels, beavers, rats, porcupines, mice
Tamandua
Red squirrel
Lagomorpha
Chisel-like incisors; hind legs longer than forelegs and adapted for running and jumping; herbivorous
Primates
Opposable thumbs; forward-facing eyes; well-developed cerebral cortex; omnivorous
Rabbits, hares, picas
Lemurs, monkeys, chimpanzees, gorillas,
humans
Golden lion tamarin
Jackrabbit
Figure Exploring: Mammalian Diversity.
Carnivora
Sharp, pointed canine teeth and molars for shearing; carnivorous
Perissodactyla
Hooves with an odd number of toes on each foot; herbivorous
Dogs, wolves, bears, cats, weasels, otters, seals, walruses
Horses, zebras, tapirs, rhinoceroses
Coyote
Indian rhinoceros
Cetartiodactyla
Hooves with an even number of toes on each foot; herbivorous
Chiroptera
Adapted for flight; broad skinfold that extends from elongated fingers to body and legs; carnivorous or herbivorous
Artiodactyls Sheep, pigs, cattle, deer, giraffes
Bats
Frog-eating bat
Bighorn sheep
Cetaceans
Aquatic; streamlined body;
paddle-like fore-limbs and
no hind limbs; thick layer
of insulating blubber; carnivorous
Eulipotyphla
Eat mainly insects and other small invertebrates
Whales, dolphins, porpoises
“Core insectivores”: some moles, some shrews
Pacific white- sided porpoise
Star-nosed mole 26

27. Primates
The mammalian order Primates includes lemurs, tarsiers, monkeys, and apes
Humans are members of the ape group
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28. Derived Characters of Primates
Most primates have hands and feet adapted for grasping, and flat nails
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29. 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)
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30. Living Primates There are three main groups of living primates
Lemurs, lorises, and pottos
Tarsiers
Anthropoids (monkeys and apes)
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31. Figure 34.42
Figure Coquerel’s sifakas (Propithecus verreauxi coquereli), a type of lemur. 31

32. Lemurs, lorises, and bush babies
Figure 34.43
Lemurs, lorises, and bush babies
ANCESTRAL PRIMATE
Tarsiers
New World monkeys
Old World monkeys
Anthropoids
Gibbons
Orangutans
Gorillas
Figure A phylogenetic tree of primates.
Chimpanzees and bonobos
Humans 60 50 40 30 20 10
Time (millions of years ago) 32

33. 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
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34. New World monkey: spider monkey (b) Old World monkey: macaque
Figure 34.44
Figure New World monkeys and Old World monkeys.
(a)
New World monkey: spider monkey
(b) Old World monkey: macaque 34

35. Apes diverged from Old World monkeys about 20–25 million years ago
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 20–25 million years ago
Video: Gibbons Brachiating
Video: Chimp Agonistic Behavior
Video: Chimp Cracking Nut
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36. (a) Gibbon (b) Orangutan (c) Gorilla (d) Chimpanzees (e) Bonobos
Figure 34.45
(a) Gibbon
(b) Orangutan
(c) Gorilla
(d) Chimpanzees
Figure Nonhuman apes.
(e) Bonobos 36

37. Concept 34.8: 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
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38. 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
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39. 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
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40. Figure 34.46
Paranthropus robustus
Homo ergaster
Homo neanderthalensis
Homo sapiens ?
Paranthropus boisei
0.5
1.0
1.5
Australopithecus africanus
2.0
Kenyanthropus platyops
2.5
Australopithecus garhi
Australo- pithecus anamensis
Millions of years ago
3.0
Homo erectus
3.5
Homo rudolfensis
Homo habilis
4.0
4.5
Figure A timeline for some selected hominin species.
Australopithecus afarensis
5.0
Ardipithecus ramidus
5.5
6.0
Orrorin tugensis
6.5
Sahelanthropus tchadensis
7.0 40

41. Hominins originated in Africa about 6–7 million years ago
Early hominins show evidence of small brains and increasing bipedalism
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42. Figure 34.47
Figure The skeleton of “Ardi,” a 4.4-million-year-old hominin, Ardipithecus ramidus. 42

43. Australopiths
Australopiths are a paraphyletic assemblage of hominins living between 4 and 2 million years ago
Some species, such as Australopithecus afarensis walked fully erect
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44. (a) The Laetoli footprints (b) Artist’s reconstruction of A. afarensis
Figure 34.48
Figure Evidence that hominins walked upright 3.5 million years ago.
(a) The Laetoli footprints
(b) Artist’s reconstruction of A. afarensis 44

45. Bipedalism
Hominins began to walk long distances on two legs about 1.9 million years ago
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46. Tool Use
The oldest evidence of tool use, cut marks on animal bones, is 2.5 million years old
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47. 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”
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48. Homo ergaster was the first fully bipedal, large-brained 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
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49. Homo ergaster fossils were previously assigned to Homo erectus; most paleoanthropologists now recognize these as separate species
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50. Figure 34.49
Figure Fossil of Homo ergaster. 50

51. Homo erectus originated in Africa by 1.8 million years ago
It was the first hominin to leave Africa
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52. 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
Debate is ongoing about the extent to which genetic material was exchanged between neanderthals and Homo sapiens
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53. Hypothesis: Neanderthals gave rise to European humans.
Figure 34.50
EXPERIMENT
Hypothesis: Neanderthals gave rise to European humans.
Expected phylogeny:
Chimpanzees
Neanderthals
Living Europeans
Other living humans
RESULTS
Chimpanzees
Figure Inquiry: Did Neanderthals give rise to European humans?
Neanderthal 1
Neanderthal 2
European and other living humans 53

54. Homo Sapiens Homo sapiens appeared in Africa by 195,000 years ago
All living humans are descended from these African ancestors
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55. Figure 34.51
Figure A 160,000-year-old fossil of Homo sapiens. 55

56. Humans first arrived in the New World sometime before 15,000 years ago
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
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57. In 2002, a 77,000-year-old artistic carving was found in South Africa
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
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58. Figure 34.52
Figure Art, a human hallmark. 58