1. LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick The Origin and Evolution of Vertebrates Chapter 34

2. 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 © 2011 Pearson Education, Inc.

3. Figure 34.2 ANCESTRAL DEUTEROSTOME Notochord Common ancestor of chordates Head Vertebral column Jaws, mineralized skeleton Lungs or lung derivatives Lobed fins Limbs with digits Amniotic egg Milk Echinodermata Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes

4. 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 1.Notochord: 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 © 2011 Pearson Education, Inc.

5. Figure 34.3 Muscle segments Notochord Dorsal, hollow nerve cord Muscular, post-anal tail Pharyngeal slits or clefts Anus Mouth

6. . 2.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 3.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 © 2011 Pearson Education, Inc.

7. 4.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 © 2011 Pearson Education, Inc. Pharyngeal Slits or Clefts

8. Lancelets (Cephalochordata) Lancelets are named for their bladelike shape They are marine suspension feeders that retain characteristics of the chordate body plan as adults. Larvae feed on plankton, earliest living chordates Undergo metamorphosis. © 2011 Pearson Education, Inc.

9. Figure 34.UN01 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

10. Figure 34.4 Mouth Cirri Pharyngeal slits Atrium Digestive tract Atriopore Segmental muscles Anus Notochord Tail Dorsal, hollow nerve cord 1 cm

11. Tunicates (Urochordata) Tunicates are more closely related to other chordates than are lancelets Trunicates 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, trunicates, or “sea squirts,” shoot water through their excurrent siphon Tunicates are highly derived and have fewer Hox genes than other vertebrates © 2011 Pearson Education, Inc.

12. Figure 34.UN02 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

13. Figure 34.5 Notochord Dorsal, hollow nerve cord Tail Muscle segments Intestine Stomach Atrium Pharynx with slits (a) Tunicate larva (b) Adult tunicate (c) Adult tunicate Excurrent siphon Incurrent siphon Water flow Excurrent siphon Anus Intestine Esophagus Stomach Incurrent siphon to mouth Excurrent siphon Atrium Tunic Pharynx with numerous slits

14. 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 Genome sequencing suggests that –Genes associated with the heart and thyroid are common to all chordates –Genes associated with transmission of nerve impulses are unique to vertebrates © 2011 Pearson Education, Inc.

15. Concept 34.2: Craniates are chordates that have a head The origin of a head enabled chordates to coordinate more complex movement and feeding behaviors Craniates share some characteristics: a skull, brain, eyes, and other sensory organs © 2011 Pearson Education, Inc.

16. Derived Characters of Craniates Craniates have two clusters of Hox genes; lancelets and tunicates have only one cluster One feature unique to craniates is the neural crest, a collection of cells near the dorsal margins of the closing neural tube in an embryo Neural crest cells give rise to a variety of structures, including some of the bones and cartilage of the skull © 2011 Pearson Education, Inc.

17. Dorsal edges of neural plate Neural crest Neural tube Notochord Migrating neural crest cells (a) (b) (c) Skull bones and cartilage derived from neural crest cells Figure 34.7

18. In aquatic craniates the pharyngeal clefts evolved into gill slits Craniates have a higher metabolism and are more muscular than tunicates and lancelets Craniates have a heart with at least two chambers, red blood cells with hemoglobin, and kidneys © 2011 Pearson Education, Inc.

19. Hagfishes The most basal group of craniates is Myxini, the hagfishes Hagfishes have a cartilaginous skull and axial rod of cartilage derived from the notochord, but lack jaws and vertebrae They have a small brain, eyes, ears, and tooth-like formations Hagfishes are marine; most are bottom-dwelling scavengers © 2011 Pearson Education, Inc.

20. Figure 34.UN03 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

21. Figure 34.9 Slime glands

22. Concept 34.3: Vertebrates are craniates that have a backbone During the Cambrian period, a lineage of craniates evolved into vertebrates Vertebrates became more efficient at capturing food and avoiding being eaten © 2011 Pearson Education, Inc.

23. Derived Characters of Vertebrates Vertebrates underwent a second gene duplication involving the Dlx family of transcription factors Vertebrates have the following derived characters –Vertebrae enclosing a spinal cord –An elaborate skull –Fin rays, in the aquatic forms © 2011 Pearson Education, Inc.

24. Lampreys (Petromyzontida) Lampreys represent the oldest living lineage of vertebrates, most are parasite,penetrates fish skin to ingest blood They are jawless vertebrates that feed by clamping their mouth onto a live fish They inhabit various marine and freshwater habitats, larvae a suspension feeder They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord, skeleton made of cartilage © 2011 Pearson Education, Inc.

25. Figure 34.UN04 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

26. Figure 34.10

27. Fossils of Early Vertebrates Conodonts were the first vertebrates with mineralized skeletal elements in their mouth and pharynx Their fossilized dental elements are common in the fossil record. They use them for predation or savaging Other armored, jawless vertebrates had defensive plates of bone on their skin. They became extinct after the Devonian period. © 2011 Pearson Education, Inc.

28. Figure 34.11 Dental elements (within head)

29. Figure 34.12 Pteraspis Pharyngolepis

30. Origins of Bone and Teeth Mineralization appears to have originated with vertebrate mouthparts The vertebrate endoskeleton became fully mineralized much later, they were relatively late in the history of vertebrate One hypothesis is that mineralization was associated with a transition in feeding mechanisms. It was an adaptation that allowed animals to become scavengers and predators © 2011 Pearson Education, Inc.

31. Concept 34.4: 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 Derived Characters of Gnathostomes Gnathostomes have jaws that might have evolved from skeletal supports(skeletal rod) of the pharyngeal slits © 2011 Pearson Education, Inc.

32. Figure 34.13 Gill slits Cranium Skeletal rods Mouth

33. 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 © 2011 Pearson Education, Inc.

34. Figure 34.14 0.5 m

35. 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,some of the biggest and most successful vertebrate predators in ocean. A second subclass is composed of a few dozen species of ratfishes © 2011 Pearson Education, Inc.

36. Figure 34.UN05 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

37. Figure 34.15 (a) Blacktip reef shark (Carcharhinus melanopterus) (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei) Dorsal fins Pectoral fins Pelvic fins

38. 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; 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 © 2011 Pearson Education, Inc.

39. 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 © 2011 Pearson Education, Inc.

40. The reproductive tract, excretory system, and digestive tract empty into a common cloaca © 2011 Pearson Education, Inc.

41. 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 includes the bony fish and tetrapods Aquatic osteichthyans are the vertebrates we informally call fishes © 2011 Pearson Education, Inc.

42. Figure 34.UN06 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

43. 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 © 2011 Pearson Education, Inc.

44. Figure 34.16 Nostril Brain Spinal cord Swim bladder Dorsal fin Adipose fin Caudal fin Cut edge of operculum Gills Kidney Heart Liver Stomach Intestine Gonad Pelvic fin Anus Anal fin Lateral line Urinary bladder

45. Ray-Finned Fishes Actinopterygii, the ray-finned fishes, includes 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 © 2011 Pearson Education, Inc. Video: Clownfish and Anemone Video: Coral Reef Video: Seahorse Camouflage

46. Figure 34.17 Yellowfin tuna (Thunnus albacares) Red lionfish (Pterois volitans) Common sea horse (Hippocampus ramulosus) Fine-spotted moray eel (Gymnothorax dovii)

47. Lobe-Fins The lobe-fins (Sarcopterygii) have muscular pelvic and pectoral fins Lobe-fins also originated in the Silurian period © 2011 Pearson Education, Inc.

48. Figure 34.18 Lower jaw Scaly covering Dorsal spine 5 cm

49. 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 © 2011 Pearson Education, Inc.

50. Figure 34.19

51. Concept 34.5: 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 © 2011 Pearson Education, Inc.

52. 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 © 2011 Pearson Education, Inc.

53. 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 –Fins with the bone pattern of a tetrapod limb © 2011 Pearson Education, Inc.

54. Figure 34.20 Flat skull Eyes on top of skull Head Neck Shoulder bones Ribs Scales Fin Fin skeleton Elbow Radius Humerus Ulna “Wrist” Scales Fins Gills and lungs Neck Ribs Fin skeleton Flat skull Eyes on top of skull Tetrapod Characters Fish Characters

55. Tiktaalik could most likely prop itself on its fins, but not walk The first tetrapods appeared 365 million years ago © 2011 Pearson Education, Inc.

56. Figure 34.21 Lungfishes Limbs with digits Amphibians Amniotes Silurian PALEOZOIC Devonian Carboniferous Permian 415 400385 370 355 3403253102952802650 Time (millions of years ago) Key to limb bones Ulna Radius Humerus Eusthenopteron Panderichthys Tiktaalik Acanthostega Tulerpeton

57. Amphibians Amphibians (class Amphibia) are represented by about 6,150 species Order Urodela includes salamanders, which have tails © 2011 Pearson Education, Inc.

58. Figure 34.UN07 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

59. Figure 34.22 (a) Order Urodela (salamanders) (b) Order Anura (frogs) Order Apoda (caecilians) (c)

60. Amphibian means “both ways of life,” referring to the metamorphosis of an aquatic larva into a terrestrial adult Most amphibians have moist skin that complements the lungs in gas exchange 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 © 2011 Pearson Education, Inc.

61. (a) Tadpole (b) During metamorphosis (c) Mating adults Figure 34.23

62. Figure 34.24

63. Amphibian populations have been declining in recent decades The causes include a disease-causing chytrid fungus, habitat loss, climate change, and pollution © 2011 Pearson Education, Inc.

64. 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 mammals © 2011 Pearson Education, Inc.

65. ANCESTRAL AMNIOTE Parareptiles Turtles Crocodilians Pterosaurs Ornithischian dinosaurs Saurischian dinosaurs other than birds Birds Plesiosaurs Ichthyosaurs Tuataras Squamates Mammals Reptiles Synapsids Diapsids Archosaurs Lepidosaurs Dinosaurs Saurischians Figure 34.25

66. 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 © 2011 Pearson Education, Inc.

67. Figure 34.26 Extraembryonic membranes Shell Amniotic cavity with amniotic fluid Embryo Amnion Allantois Chorion Yolk sac Yolk (nutrients) Albumen

68. 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 © 2011 Pearson Education, Inc.

69. 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 early tetrapods The earliest amniotes were small predators with sharp teeth and long jaws © 2011 Pearson Education, Inc.

70. Figure 34.27

71. Reptiles The reptile clade includes the tuataras, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs Reptiles have scales that create a waterproof barrier Most reptiles lay shelled eggs on land © 2011 Pearson Education, Inc.

72. Figure 34.UN08 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

73. Figure 34.28

74. 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 © 2011 Pearson Education, Inc.

75. The Origin and Evolutionary Radiation of Reptiles The oldest reptilian fossils date to the Carboniferous period The first major group to emerge were parareptiles, which were mostly large, stocky quadrupedal herbivores © 2011 Pearson Education, Inc.

76. 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 © 2011 Pearson Education, Inc.

77. 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 © 2011 Pearson Education, Inc.

78. Debate continues about whether dinosaurs were endothermic or ectothermic 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 © 2011 Pearson Education, Inc.

79. Dinosaurs, with the exception of birds, became extinct by the end of the Cretaceous Their extinction may have been partly caused by an asteroid © 2011 Pearson Education, Inc.

80. Lepidosaurs One surviving lineage of lepidosaurs is represented by two species of lizard-like reptiles called tuataras © 2011 Pearson Education, Inc.

81. (a) Tuatara (Sphenodon punctatus) Australian thorny devil lizard (Moloch horridus) (b) (d) Eastern box turtle (Terrapene carolina carolina) (c)Wagler’s pit viper (Tropidolaemus wagleri) (e) American alligator (Alligator mississippiensis) Figure 34.29

82. The other major living lineage of lepidosaurs consists of the squamates, the lizards and snakes Lizards are the most numerous and diverse reptiles, apart from birds © 2011 Pearson Education, Inc. Video: Galápagos Marine Iguana

83. Figure 34.29b Australian thorny devil lizard (Moloch horridus) (b)

84. Snakes are legless lepidosaurs that evolved from lizards Snakes are carnivorous; some are also venomous © 2011 Pearson Education, Inc. Video: Snake Ritual Wrestling

85. Figure 34.29c (c)Wagler’s pit viper (Tropidolaemus wagleri)

86. Turtles All turtles have a boxlike shell made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs Some turtles have adapted to deserts and others live entirely in ponds and rivers © 2011 Pearson Education, Inc. Video: Galápagos Tortoise

87. Figure 34.29d (d)Eastern box turtle (Terrapene carolina carolina)

88. Alligators and Crocodiles Crocodilians (alligators and crocodiles) belong to an archosaur lineage that dates back to the late Triassic © 2011 Pearson Education, Inc.

89. Figure 34.29e (e) American alligator (Alligator mississippiensis)

90. Birds Birds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight © 2011 Pearson Education, Inc.

91. Many characters of birds are adaptations that facilitate flight The major adaptation is wings with keratin feathers. Flight enhances hunting and scavenging, escape from terrestrial predators, and migration, well developed vision and sensory Flight requires a great expenditure of energy, acute vision, and fine muscle control Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth Derived Characters of Birds © 2011 Pearson Education, Inc.

92. Figure 34.30 (a) Wing Vane Shaft Forearm Wrist Shaft Barb Barbule Hook (c) Feather structure (b) Bone structure Finger 1 Finger 2 Finger 3 Palm

93. Birds probably descended from small theropods, a group of carnivorous dinosaurs Early feathers might have evolved for insulation, camouflage, or courtship display The Origin of Birds © 2011 Pearson Education, Inc.

94. 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 © 2011 Pearson Education, Inc.

95. Airfoil wing with contour feathers Long tail with many vertebrae Toothed beak Wing claw Figure 34.31

96. 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 Living Birds © 2011 Pearson Education, Inc.

97. Figure 34.32

98. The demands of flight have rendered the general body form of many flying birds similar to one another © 2011 Pearson Education, Inc. Video: Flapping Geese Video: Soaring Hawk Video: Swans Taking Flight

99. Figure 34.33

100. Figure 34.34

101. Figure 34.35

102. Figure 34.36

103. Concept 34.7: Mammals are amniotes that have hair and produce milk Mammals, class Mammalia, are represented by more than 5,300 species © 2011 Pearson Education, Inc.

104. Figure 34.UN09 Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia

105. 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 © 2011 Pearson Education, Inc.

106. Early Evolution of Mammals Mammals evolved from synapsids Two bones that formerly made up the jaw joint were incorporated into the mammalian middle ear © 2011 Pearson Education, Inc.

107. Key Articular Quadrate Dentary Squamosal Biarmosuchus, a synapsid Temporal fenestra Jaw joint (a) Articular and quadrate bones in the jaw Eardrum Middle ear Stapes Inner ear Sound Present-day reptile (b) Articular and quadrate bones in the middle ear Sound Present-day mammal Eardrum Middle ear Inner ear Stapes Incus (quadrate) Malleus (articular) Figure 34.37

108. 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 © 2011 Pearson Education, Inc.

109. Monotremes Monotremes are a small group of egg-laying mammals consisting of echidnas and the platypus © 2011 Pearson Education, Inc.

110. Figure 34.38

111. 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 © 2011 Pearson Education, Inc.

112. Figure 34.39 (a) A young brushtail possum (b) Long-nosed bandicoot

113. In some species, such as the bandicoot, the marsupium opens to the rear of the mother’s body © 2011 Pearson Education, Inc.

114. Figure 34.39b (b) Long-nosed bandicoot

115. In Australia, convergent evolution has resulted in a diversity of marsupials that resemble the eutherians in other parts of the world © 2011 Pearson Education, Inc.

116. Figure 34.40 Plantigale Marsupial mammals Eutherian mammals Marsupial mole Sugar glider Wombat Tasmanian devil Kangaroo Deer mouse Mole Flying squirrel Woodchuck Wolverine Patagonian cavy

117. 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 © 2011 Pearson Education, Inc.

118. ANCESTRAL MAMMAL Monotremes (5 species) Marsupials (324 species) Eutherians (5,010 species) Monotremata Marsupialia Proboscidea Sirenia Tubulidentata Hyracoidea Afrosoricida Macroscelidea Xenarthra Rodentia Lagomorpha Primates Dermoptera Scandentia Carnivora Cetartiodactyla Perissodactyla Chiroptera Eulipotyphia Pholidota Figure 34.41a

119. Monotremata Orders and ExamplesMain CharacteristicsOrders and ExamplesMain Characteristics Platypuses, echidnas Echidna Proboscidea Elephants African elephant Sirenia Manatees, dugongs Manatee Lay eggs; no nipples; young suck milk from fur of mother Long, muscular trunk; thick, loose skin; upper incisors elongated as tusks Aquatic; finlike fore- limbs and no hind limbs; herbivorous Xenarthra Sloths, anteaters, armadillos Tamandua Lagomorpha Rabbits, hares, picas Jackrabbit 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 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 fore-limbs and no hind limbs; thick layer of insulating blubber; carnivorous Carnivora Dogs, wolves, bears, cats, weasels, otters, seals, walruses Coyote Cetartiodactyla Artiodactyls Sheep, pigs, cattle, deer, giraffes Cetaceans Whales, dolphins, porpoises Marsupialia Kangaroos, opossums, koalas Koala Completes embryonic development in pouch on mother’s body Tubulidentata Aardvarks Aardvark Teeth consisting of many thin tubes cemented together; eats ants and termites Hyracoidea Hyraxes Rock hyrax Short legs; stumpy tail; herbivorous; complex, multi- chambered stomach 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 Perissodactyla Horses, zebras, tapirs, rhinoceroses Indian rhinoceros Hooves with an odd number of toes on each foot; herbivorous Chiroptera Bats Frog-eating bat Eulipotyphla “Core insectivores”: some moles, some shrews Star-nosed mole Eat mainly insects and other small invertebrates Adapted for flight; broad skinfold that extends from elongated fingers to body and legs; carnivorous or herbivorous Bighorn sheep Pacific white- sided porpoise Figure 34.41b

120. Primates The mammalian order Primates includes lemurs, tarsiers, monkeys, and apes Humans are members of the ape group © 2011 Pearson Education, Inc.

121. Most primates have hands and feet adapted for grasping, and flat nails Derived Characters of Primates © 2011 Pearson Education, Inc.

122. 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) © 2011 Pearson Education, Inc.

123. There are three main groups of living primates –Lemurs, lorises, and pottos –Tarsiers –Anthropoids (monkeys and apes) Living Primates © 2011 Pearson Education, Inc.

124. Figure 34.42

125. The oldest known anthropoid fossils, about 45 million years old, indicate that tarsiers are more closely related to anthropoids than to lemurs © 2011 Pearson Education, Inc.

126. Figure 34.43 ANCESTRAL PRIMATE Time (millions of years ago) 60 50 40 30 20100 Lemurs, lorises, and bush babies Tarsiers New World monkeys Old World monkeys Gibbons Orangutans Gorillas Chimpanzees and bonobos Humans Anthropoids

127. 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 © 2011 Pearson Education, Inc.

128. Figure 34.44 (b) Old World monkey: macaque (a) New World monkey: spider monkey

129. 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 © 2011 Pearson Education, Inc. Video: Gibbons Brachiating Video: Chimp Agonistic Behavior Video: Chimp Cracking Nut

130. (a) Gibbon (b) Orangutan (c) Gorilla (d) Chimpanzees (e) Bonobos Figure 34.45

131. 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 © 2011 Pearson Education, Inc.

132. 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 © 2011 Pearson Education, Inc.

133. The human and chimpanzee genomes are 99% identical Changes in regulatory genes can have large effects © 2011 Pearson Education, Inc.

134. 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 © 2011 Pearson Education, Inc.

135. Figure 34.46 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 0 Millions of years ago Australo- pithecus anamensis Kenyanthropus platyops Australopithecus africanus Paranthropus boisei Paranthropus robustus Homo ergaster Homo neanderthalensis Homo sapiens Homo erectus Homo rudolfensis Homo habilis Australopithecus garhi ? Australopithecus afarensis Ardipithecus ramidus Orrorin tugensis Sahelanthropus tchadensis

136. Hominins originated in Africa about 6–7 million years ago Early hominins show evidence of small brains and increasing bipedalism © 2011 Pearson Education, Inc.

137. Figure 34.47

138. 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 © 2011 Pearson Education, Inc.

139. 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 © 2011 Pearson Education, Inc.

140. Figure 34.48 (a) The Laetoli footprints (b) Artist’s reconstruction of A. afarensis

141. “Robust” australopiths had sturdy skulls and powerful jaws “Gracile” australopiths were more slender and had lighter jaws © 2011 Pearson Education, Inc.

142. Bipedalism Hominins began to walk long distances on two legs about 1.9 million years ago © 2011 Pearson Education, Inc.

143. Tool Use The oldest evidence of tool use, cut marks on animal bones, is 2.5 million years old © 2011 Pearson Education, Inc.

144. 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” © 2011 Pearson Education, Inc.

145. 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 © 2011 Pearson Education, Inc.

146. Homo ergaster fossils were previously assigned to Homo erectus; most paleoanthropologists now recognize these as separate species © 2011 Pearson Education, Inc.

147. Figure 34.49

148. Homo erectus originated in Africa by 1.8 million years ago It was the first hominin to leave Africa © 2011 Pearson Education, Inc.

149. 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 © 2011 Pearson Education, Inc.

150. Hypothesis: Neanderthals gave rise to European humans. Expected phylogeny: Chimpanzees Neanderthals Living Europeans Other living humans Chimpanzees Neanderthal 1 Neanderthal 2 European and other living humans EXPERIMENT RESULTS Figure 34.50

151. Homo Sapiens Homo sapiens appeared in Africa by 195,000 years ago All living humans are descended from these African ancestors © 2011 Pearson Education, Inc.

152. Figure 34.51

153. 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 © 2011 Pearson Education, Inc.

154. 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 © 2011 Pearson Education, Inc.

155. Figure 34.52

156. Clade Description Chordates: notochord; dorsal, hollow nerve cord; pharyngeal slits; post-anal tail Craniates: two sets of Hox genes, neural crest Vertebrates: Dix genes duplication, backbone of vertebrae Gnathostomes: hinged jaws, four sets of Hox genes Osteichthyans: bony skeleton Lobe-fins: muscular fins or limbs Tetrapods: four limbs, neck, fused pelvic girdle Amniotes: amniotic egg, rib cage ventilation Cephalochordata (lancelets) Urochordata (tunicates) Myxini (hagfishes and relatives) Petromyzontida (lampreys) Chondrichthyes (sharks, rays, skates, ratfishes) Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Dipnoi (lungfishes) Amphibia (salamanders, frogs, caecilians) Reptilia (tuataras, lizards and snakes, turtles, crocodilians, birds) Mammalia (monotremes, marsupials, eutherians) Basal chordates; marine suspension feeders that exhibit four key derived characters of chordates Marine suspension feeders; larvae display the derived traits of chordates Jawless marine organisms; have head that includes a skull and brain, eyes, and other sensory organs Jawless vertebrates; 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 Ancient lineage of aquatic lobe-fins still surviving in Indian Ocean Freshwater lobe-fins with both lungs and gills; sister group of tetrapods 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 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.UN10