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The Origin and Evolution of VertebratesLecture Presentation by Nicole Tunbridge andKathleen Fitzpatrick34CAMPBELLBIOLOGYReece Urry Cain Wasserman Minorsky Jackson 2014 Pearson Education, Inc.TENTHEDITION 2014 Pearson Education, Inc.Half a Billion Years of BackbonesEarly in the Cambrian period, about 530 million years ago, an astonishing variety of invertebrate animals inhabited Earths oceansOne type of animal gave rise to vertebrates, one of the most successful groups of animalsThe animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone 2014 Pearson Education, Inc.2

Figure 34.1 2014 Pearson Education, Inc.Figure 34.1 What is the relationship between this ancient organism and humans?3One lineage of vertebrates colonized land 365 million years agoThey gave rise to modern amphibians, reptiles (including birds), and mammalsThere are more than 57,000 species of vertebrates, including the largest organisms ever to live on EarthVertebrates have great disparity, a wide range of differences within the group 2014 Pearson Education, Inc.4Concept 34.1: Chordates have a notochord and a dorsal, hollow nerve cordChordates (phylum Chordata) are bilaterian animals that belong to the clade of animals known as DeuterostomiaChordates comprise all vertebrates and two groups of invertebrates, the urochordates and cephalochordates 2014 Pearson Education, Inc.5

Figure 34.2EchinodermataCephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammaliaMilkAmniotic eggLimbs with digitsLobed finsLungs or lung derivativesJaws, mineralized skeletonVertebraeCommon ancestorof chordatesChordatesVertebratesGnathostomesOsteichthyansLobe-finsTetrapodsAmniotesNotochordANCESTRALDEUTERO-STOME 2014 Pearson Education, Inc.Figure 34.2 Phylogeny of living chordates6

Figure 34.2aEchinodermataCephalochordataUrochordataMyxiniPetromyzontidaCommon ancestor of chordatesNotochordANCESTRALDEUTERO-STOMEChondrichthyesJaws, mineralized skeletonVertebrae 2014 Pearson Education, Inc.Figure 34.2a Phylogeny of living chordates (part 1)7

Figure 34.2bActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammaliaMilkAmniotic eggLimbs with digitsLobed finsLungs or lung derivativesChondrichthyesJaws, mineralized skeleton 2014 Pearson Education, Inc.Figure 34.2b Phylogeny of living chordates (part 2)8Derived Characters of ChordatesAll chordates share a set of derived charactersSome species have some of these traits only during embryonic developmentFour key characters of chordatesNotochordDorsal, hollow nerve cordPharyngeal slits or cleftsMuscular, post-anal tail 2014 Pearson Education, Inc.9

Figure 34.3NotochordDorsal, hollow nerve cordMusclesegmentsAnusPost-anal tailPharyngeal slits or cleftsMouth 2014 Pearson Education, Inc.Figure 34.3 Chordate characteristics10NotochordThe notochord is a longitudinal, flexible rod between the digestive tube and nerve cordIt provides skeletal support throughout most of the length of a chordateIn most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the embryonic notochord 2014 Pearson Education, Inc.11Dorsal, Hollow Nerve CordThe nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochordThe nerve cord develops into the central nervous system: the brain and the spinal cord 2014 Pearson Education, Inc.12Pharyngeal Slits or CleftsIn most chordates, grooves in the pharynx called pharyngeal clefts develop into slits that open to the outside of the bodyFunctions of pharyngeal slitsSuspension-feeding structures in many invertebrate chordatesGas exchange in vertebrates (except vertebrates with limbs, the tetrapods)Develop into parts of the ear, head, and neck in tetrapods 2014 Pearson Education, Inc.13Muscular, Post-Anal TailChordates have a tail posterior to the anusIn many species, the tail is greatly reduced during embryonic developmentThe tail contains skeletal elements and musclesIt provides propelling force in many aquatic species 2014 Pearson Education, Inc.14LanceletsLancelets (Cephalochordata) are named for their bladelike shapeThey are marine suspension feeders that retain characteristics of the chordate body plan as adults 2014 Pearson Education, Inc.15

Figure 34.UN01CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 34.UN01 In-text figure, Cephalochordata mini-tree, p. 71416

Figure 34.4CirriMouthPharyngeal slitsAtriumDigestive tractAtrioporeSegmentalmusclesAnusTailDorsal, hollownerve cordNotochord1 cm 2014 Pearson Education, Inc.Figure 34.4 The lancelet Branchiostoma, a cephalochordate17

Figure 34.4a1 cm 2014 Pearson Education, Inc.Figure 34.4a The lancelet Branchiostoma, a cephalochordate (part 1: photo) 18TunicatesTunicates (Urochordata) are more closely related to other chordates than are lanceletsTunicates most resemble chordates during their larval stage, which may last only a few minutesAs an adult, a tunicate draws in water through an incurrent siphon, filtering food particlesWhen attacked, tunicates, or sea squirts, shoot water through their excurrent siphon 2014 Pearson Education, Inc.19

Figure 34.UN02CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN02 In-text figure, Urochordata mini-tree, p. 71520

Figure 34.5NotochordDorsal, hollownerve cordWater flowExcurrentsiphonExcurrentsiphonIncurrentsiphonTailMusclesegmentsIntestineStomachAtriumPharynx with slits(a) A tunicate larva(b) An adult tunicateStomachEsophagusIntestineAnusTunicPharynxwithnumerousslitsAtriumIncurrentsiphonto mouthExcurrentsiphon(c) An adult tunicate 2014 Pearson Education, Inc.Figure 34.5 A tunicate, a urochordate21

Figure 34.5aNotochordDorsal, hollownerve cordExcurrentsiphonIncurrentsiphonTailMusclesegmentsIntestineStomachAtriumPharynx with slits(a) A tunicate larva(b) An adult tunicateExcurrentsiphonWater flowStomachEsophagusIntestineAnusTunicPharynxwithnumerousslitsAtriumIncurrentsiphonto mouth 2014 Pearson Education, Inc.Figure 34.5a A tunicate, a urochordate (part 1: art)22

Figure 34.5bTunicPharynxwithnumerousslitsAtriumIncurrentsiphonto mouthExcurrentsiphon(c) An adult tunicate 2014 Pearson Education, Inc.Figure 34.5b A tunicate, a urochordate (part 2: photo)23Tunicates are highly derived and have fewer Hox genes than other vertebrates 2014 Pearson Education, Inc.24Early Chordate EvolutionAncestral chordates may have resembled lanceletsThe same Hox genes that organize the vertebrate brain are expressed in the lancelets simple nerve cord tipSequencing of the tunicate genome indicates thatGenes associated with the heart and thyroid are common to all chordatesGenes associated with transmission of nerve impulses are unique to vertebrates

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Figure 34.6Nerve cord of lancelet embryoBrain of vertebrate embryo(shown straightened)ForebrainMidbrainHindbrainHox3OtxBF1Hox3OtxBF1 2014 Pearson Education, Inc.Figure 34.6 Expression of developmental genes in lancelets and vertebrates26Concept 34.2: Vertebrates are chordates that have a backboneA skeletal system and complex nervous system have allowed vertebrates efficiency at two essential tasksCapturing foodEvading predators 2014 Pearson Education, Inc.27Derived Characters of VertebratesVertebrates have two or more sets of Hox genes; lancelets and tunicates have only one clusterVertebrates have the following derived charactersVertebrae enclosing a spinal cordAn elaborate skullFin rays, in the aquatic forms 2014 Pearson Education, Inc.28Hagfishes and LampreysFossil evidence shows that the earliest vertebrates lacked jawsOnly two lineages of jawless vertebrates remain today: the hagfishes and the lampreysMembers of these groups lack a backboneThe presence of rudimentary vertebrae and the results of phylogenetic analysis indicate that both hagfishes and lampreys are vertebrates 2014 Pearson Education, Inc.29Together, the hagfishes and lampreys form a clade of living jawless vertebrates, the cyclostomesVertebrates with jaws make up a much larger clade, the gnathostomes

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Figure 34.UN03CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN03 In-text figure, Myxini and Petromyzontida mini-tree, p. 71731HagfishesHagfishes (Myxini) are jawless vertebrates that have a cartilaginous skull, reduced vertebrae, and a flexible rod of cartilage derived from the notochordThey have a small brain, eyes, ears, and tooth-like formationsHagfishes are marine; most are bottom-dwelling scavengers 2014 Pearson Education, Inc.32

Figure 34.7Slime glands 2014 Pearson Education, Inc.Figure 34.7 A hagfish33LampreysLampreys (Petromyzontida) are parasites that feed by clamping their mouth onto a live fishThey inhabit various marine and freshwater habitats They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord 2014 Pearson Education, Inc.34

Figure 34.8 2014 Pearson Education, Inc.Figure 34.8 A sea lamprey35

Figure 34.8a 2014 Pearson Education, Inc.Figure 34.8a A sea lamprey (part 1: lamprey)36

Figure 34.8b 2014 Pearson Education, Inc.Figure 34.8b A sea lamprey (part 2: lamprey mouth)37Early Vertebrate EvolutionFossils from the Cambrian explosion document the transition to craniatesThe most primitive of the fossils are those of the 3-cm-long HaikouellaHaikouella had a well-formed brain, eyes, and muscular segments, but no skull or ear organs 2014 Pearson Education, Inc.38

Figure 34.95 mmPharyngeal slitsSegmented muscles 2014 Pearson Education, Inc.Figure 34.9 Fossil of an early chordate39

Figure 34.9a5 mm 2014 Pearson Education, Inc.Figure 34.9a Fossil of an early chordate (part 1: photo)40Conodonts 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 pharynxTheir fossilized dental elements are common in the fossil record

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Figure 34.10Dental elements(withinhead)0.5 cm 2014 Pearson Education, Inc.Figure 34.10 A conodont42Other groups of jawless vertebrates were armored with defensive plates of bone on their skin 2014 Pearson Education, Inc.43

Figure 34.11PteraspisPharyngolepis 2014 Pearson Education, Inc.Figure 34.11 Jawless armored vertebrates44Origins of Bone and TeethMineralization appears to have originated with vertebrate mouthpartsThe vertebrate endoskeleton became fully mineralized much later 2014 Pearson Education, Inc.45Concept 34.3: Gnathostomes are vertebrates that have jawsToday, jawed vertebrates, or gnathostomes, outnumber jawless vertebratesGnathostomes include sharks and their relatives, ray-finned fishes, lobe-finned fishes, amphibians, reptiles (including birds), and mammals 2014 Pearson Education, Inc.46Derived Characters of GnathostomesGnathostomes (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 themThe jaws are hypothesized to have evolved by modification of skeletal rods that supported the pharyngeal (gill) slits 2014 Pearson Education, Inc.47

Figure 34.12Gill slitsCraniumModifiedskeletal rodsSkeletal rods 2014 Pearson Education, Inc.Figure 34.12 Possible step in the evolution of jawbones48Other characters common to gnathostomesGenome duplication, including duplication of Hox genesAn enlarged forebrain associated with enhanced smell and visionIn aquatic gnathostomes, the lateral line system, which is sensitive to vibrations 2014 Pearson Education, Inc.49Fossil GnathostomesThe earliest gnathostomes in the fossil record are an extinct lineage of armored vertebrates called placodermsThey appeared about 440 million years ago 2014 Pearson Education, Inc.50

Figure 34.130.5 m 2014 Pearson Education, Inc.Figure 34.13 Fossil of an early gnathostome51Another 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 2014 Pearson Education, Inc.52Chondrichthyans (Sharks, Rays, and Their Relatives)Chondrichthyans (Chondrichthyes) have a skeleton composed primarily of cartilageThe largest and most diverse group of chondrichthyans includes the sharks, rays, and skates 2014 Pearson Education, Inc.53

Figure 34.UN04CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN04 In-text figure, Chondrichthyes mini-tree, p. 72054

Figure 34.14(b) Southern stingray (Dasyatis americana)Blacktip reef shark(Carcharhinus melanopterus)(c) Spotted ratfish (Hydrolagus colliei)(a)Pelvic finsDorsal finsPectoral fins 2014 Pearson Education, Inc.Figure 34.14 Chondrichthyans55

Figure 34.14aBlacktip reef shark(Carcharhinus melanopterus)(a)Pelvic finsDorsal finsPectoral fins 2014 Pearson Education, Inc.Figure 34.14a Chondrichthyans (part 1: blacktip reef shark)56

Figure 34.14b(b) Southern stingray (Dasyatis americana) 2014 Pearson Education, Inc.Figure 34.14b Chondrichthyans (part 2: Southern stingray)57

Figure 34.14c(c) Spotted ratfish (Hydrolagus colliei) 2014 Pearson Education, Inc.Figure 34.14c Chondrichthyans (part 3: spotted ratfish)58Video: Manta Ray

2014 Pearson Education, Inc.A second subclass is composed of a few dozen species of ratfishes, or chimaeras 2014 Pearson Education, Inc.60Sharks have a streamlined body and are swift swimmersThe largest sharks are suspension feeders, but most are carnivoresSharks have a short digestive tract with a ridge called the spiral valve to increase the digestive surface areaSharks have acute senses including sight, smell, and the ability to detect electrical fields from nearby animals 2014 Pearson Education, Inc.61Shark eggs are fertilized internally but embryos can develop in different waysOviparous: Eggs hatch outside the mothers bodyOvoviviparous: The embryo develops within the uterus and is nourished by the egg yolkViviparous: The embryo develops within the uterus and is nourished through a yolk sac placenta from the mothers blood 2014 Pearson Education, Inc.62The reproductive tract, excretory system, and digestive tract empty into a common cloacaToday, sharks are severely threatened by overfishing; Pacific populations have plummeted by up to 95% 2014 Pearson Education, Inc.63Ray-Finned Fishes and Lobe-FinsThe vast majority of vertebrates belong to a clade of gnathostomes called OsteichthyesNearly all living osteichthyans have a bony endoskeletonOsteichthyans include the bony fishes and tetrapodsAquatic osteichthyans are the vertebrates we informally call fishes 2014 Pearson Education, Inc.64

Figure 34.UN05CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN05 In-text figure, Actinopterygii, Actinistia, and Dipnoi mini-tree, p. 72265Most fishes breathe by drawing water over gills protected by an operculumFishes control their buoyancy with an air sac known as a swim bladderFishes have a lateral line systemMost species are oviparous, but some have internal fertilization and birthing 2014 Pearson Education, Inc.66

Figure 34.15Cut edgeof operculumSwimbladderSpinal cordBrainNostrilGillsKidneyHeartLiverStomachIntestineGonadAnusPelvicfinUrinarybladderLateral lineAnal finCaudalfinAdipose fin(characteristicof trout)Dorsal fin 2014 Pearson Education, Inc.Figure 34.15 Anatomy of a trout, a ray-finned fish67Ray-Finned FishesActinopterygii, the ray-finned fishes, include nearly all the familiar aquatic osteichthyansRay-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.68

Figure 34.16Yellowfin tuna (Thunnus albacares)Red lionfish(Pteroisvolitans)Common seahorse,(Hippocampusramulosus)Fine-spottedmoray eel,(Gymnothoraxdovii) 2014 Pearson Education, Inc.Figure 34.16 Ray-finned fishes (Actinopterygii)69

Figure 34.16aYellowfin tuna (Thunnus albacares) 2014 Pearson Education, Inc.Figure 34.16a Ray-finned fishes (Actinopterygii) (part 1: yellowfin tuna)70

Figure 34.16bRed lionfish, (Pterois volitans) 2014 Pearson Education, Inc.Figure 34.16b Ray-finned fishes (Actinopterygii) (part 2: red lionfish)71

Figure 34.16cCommon sea horse,(Hippocampusramulosus) 2014 Pearson Education, Inc.Figure 34.16c Ray-finned fishes (Actinopterygii) (part 3: sea horse)72

Figure 34.16dFine-spotted moray eel,(Gymnothorax dovii) 2014 Pearson Education, Inc.Figure 34.16d Ray-finned fishes (Actinopterygii) (part 4: fine-spotted moray eel)73Video: 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 collapsePopulations are also affected by dams that change water flow patterns, affecting prey capture, migration, and spawning 2014 Pearson Education, Inc.77Lobe-FinsThe lobe-fins (Sarcopterygii) also originated in the Silurian periodThey have muscular pelvic and pectoral fins that they use to swim and walk underwater across the substrate 2014 Pearson Education, Inc.78

Figure 34.17LowerjawScalycoveringDorsalspine5 cm 2014 Pearson Education, Inc.Figure 34.17 A reconstruction of an ancient lobe-fin79

Figure 34.17aLowerjawScalycoveringDorsalspine5 cm 2014 Pearson Education, Inc.Figure 34.17a A reconstruction of an ancient lobe-fin (part 1: photo)80Three lineages survive and include coelacanths, lungfishes, and tetrapodsCoelacanths 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.81

Figure 34.18 2014 Pearson Education, Inc.Figure 34.18 A coelacanth (Latimeria)82The living lungfishes are all found in the Southern HemisphereThough gills are the main organs for gas exchange, they can also surface to gulp air into their lungsThe third surviving lineage of lobe-fins are tetrapods, a group that adapted to life on land

2014 Pearson Education, Inc.83Concept 34.4: Tetrapods are gnathostomes that have limbsOne 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.84Derived Characters of TetrapodsTetrapods have some specific adaptationsFour limbs, and feet with digitsA neck, which allows separate movement of the headFusion of the pelvic girdle to the backboneThe absence of gills (except some aquatic species)Ears for detecting airborne sounds 2014 Pearson Education, Inc.85The Origin of TetrapodsTiktaalik, nicknamed a fishapod, shows both fish and tetrapod characteristicsIt hadFins, gills, lungs, and scalesRibs to breathe air and support its bodyA neck and shouldersFins with the bone pattern of a tetrapod limb 2014 Pearson Education, Inc.86

Figure 34.19FishCharactersTetrapodCharactersScalesFinsGills and lungsNeckRibsFin skeletonFlat skullEyes on top of skullHeadNeckEyes on topof skullFlat skullShoulder bonesRibsElbowFinRadiusFin skeletonWristUlnaHumerusScales 2014 Pearson Education, Inc.Figure 34.19 Discovery of a fishapod: Tiktaalik87

Figure 34.19aHeadNeckEyes on topof skullFlat skullShoulder bonesFin 2014 Pearson Education, Inc.Figure 34.19a Discovery of a fishapod: Tiktaalik (part 1: detail)88

Figure 34.19bRibs 2014 Pearson Education, Inc.Figure 34.19b Discovery of a fishapod: Tiktaalik (part 2: ribs)89

Figure 34.19cScales 2014 Pearson Education, Inc.Figure 34.19c Discovery of a fishapod: Tiktaalik (part 3: scales)90

Figure 34.19dElbowRadiusFin skeletonWristUlnaHumerus 2014 Pearson Education, Inc.Figure 34.19d Discovery of a fishapod: Tiktaalik (part 4: fin skeleton)91Tiktaalik could most likely prop itself on its fins, but not walkThe first tetrapods appeared 365 million years ago 2014 Pearson Education, Inc.92

Figure 34.20LungfishesEusthenopteronPanderichthysTiktaalikAcanthostegaTulerpetonAmphibiansLimbswith digitsAmniotesSilurianPALEOZOICDevonianCarboniferousPermian4154003853703553403253102952802650Time (millions of years ago)Key tolimb bonesUlnaRadiusHumerus 2014 Pearson Education, Inc.Figure 34.20 Steps in the origin of limbs with digits93

Figure 34.20aLungfishesKey tolimb bonesUlnaRadiusHumerusEusthenopteronPanderichthysTiktaalikLobe-fins with limbs with digits SilurianPALEOZOICDevonianCarboniferousPermian4154003853703553403253102952802650Time (millions of years ago) 2014 Pearson Education, Inc.Figure 34.20a Steps in the origin of limbs with digits (part 1: lobe-fins with limbs without digits)94

Figure 34.20bAcanthostegaTulerpetonAmphibiansLimbswith digitsAmniotesSilurianPALEOZOICDevonianCarboniferousPermian4154003853703553403253102952802650Time (millions of years ago)Key tolimb bonesUlnaRadiusHumerus 2014 Pearson Education, Inc.Figure 34.20b Steps in the origin of limbs with digits (part 2: lobe-fins with limbs with digits)95AmphibiansAmphibians (class Amphibia) are represented by about 6,150 species in three cladesUrodela (salamanders)Anura (frogs) Apoda (caecilians)

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Figure 34.UN06CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN06 In-text figure, Amphibia mini-tree, p. 72697SalamandersSalamanders (urodeles) are amphibians with tailsSome are aquatic, but others live on land as adults or throughout lifePaedomorphosis, the retention of juvenile features in sexually mature organisms, is common in aquatic species 2014 Pearson Education, Inc.98

Figure 34.21(a) Order Urodela(b) Order Anura(c) Order Apoda 2014 Pearson Education, Inc.Figure 34.21 Amphibians99

Figure 34.21a(a) Order Urodela 2014 Pearson Education, Inc.Figure 34.21a Amphibians (part 1: salamanders)100FrogsFrogs (anurans) lack tails and have powerful hind legs for locomotion on landFrogs with leathery skin are called toads

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Figure 34.21b(b) Order Anura 2014 Pearson Education, Inc.Figure 34.21b Amphibians (part 2: frogs and toads)102CaeciliansCaecilians (apoda) are legless, nearly blind, and resemble earthwormsThe absence of legs is a secondary adaptation 2014 Pearson Education, Inc.103

Figure 34.21c(c) Order Apoda 2014 Pearson Education, Inc.Figure 34.21c Amphibians (part 3: caecilians)104Amphibian means both ways of life, referring to the metamorphosis of an aquatic larva into a terrestrial adultTadpoles 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 exchangeLifestyle and Ecology of Amphibians 2014 Pearson Education, Inc.105

Figure 34.22(a) The tadpole(b) During metamorphosis(c) The adults return to water to mate. 2014 Pearson Education, Inc.Figure 34.22 The dual life of a frog (Rana temporaria)106

Figure 34.22a(a) The tadpole 2014 Pearson Education, Inc.Figure 34.22a The dual life of a frog (Rana temporaria) (part 1: tadpole)107

Figure 34.22b(b) During metamorphosis 2014 Pearson Education, Inc.Figure 34.22b The dual life of a frog (Rana temporaria) (part 2: metamorphosis)108

Figure 34.22c(c) The adults return to water to mate. 2014 Pearson Education, Inc.Figure 34.22c The dual life of a frog (Rana temporaria) (part 3: mating adults)109Fertilization is external in most species, and the eggs require a moist environmentIn some species, males or females care for the eggs on their back, in their mouth, or in their stomach 2014 Pearson Education, Inc.110

Figure 34.23 2014 Pearson Education, Inc.Figure 34.23 A mobile nursery111Amphibian populations have been declining in recent decadesThe causes include a disease-causing chytrid fungus, habitat loss, climate change, and pollution 2014 Pearson Education, Inc.112Concept 34.5: Amniotes are tetrapods that have a terrestrially adapted eggAmniotes are a group of tetrapods whose living members are the reptiles, including birds, and mammals 2014 Pearson Education, Inc.113

Figure 34.24ParareptilesTurtlesCrocodiliansPterosaursOrnithischiandinosaursSaurischiandinosaursother than birdsBirdsPlesiosaursIchthyosaursTuatarasMammalsSquamates(lizards andsnakes)LepidosaursDiapsidsSynapsidsReptilesArchosaursDinosaursSaurischiansANCESTRALAMNIOTE 2014 Pearson Education, Inc.Figure 34.24 A phylogeny of amniotes114

Figure 34.24aParareptilesTurtlesCrocodiliansPterosaursOrnithischiandinosaursSaurischiandinosaursother than birdsBirdsDiapsidsReptilesArchosaursDinosaursSaurischians 2014 Pearson Education, Inc.Figure 34.24a A phylogeny of amniotes (part 1)115

Figure 34.24bPlesiosaursIchthyosaursTuatarasMammalsSquamates(lizards andsnakes)LepidosaursSynapsidsDiapsids 2014 Pearson Education, Inc.Figure 34.24b A phylogeny of amniotes (part 2)116Derived Characters of AmniotesAmniotes are named for the major derived character of the clade, the amniotic egg, which contains membranes that protect the embryoThe extraembryonic membranes are the amnion, chorion, yolk sac, and allantois 2014 Pearson Education, Inc.117

Figure 34.25Extraembryonic membranesChorionYolk(nutrients)AlbumenYolk sacAmnionShellEmbryoAllantoisAmniotic cavitywith amniotic fluidExtraembryonic membranes 2014 Pearson Education, Inc.Figure 34.25 The amniotic egg118The amniotic egg was a key adaptation to life on land The amniotic eggs of most reptiles and some mammals have a shellAmniotes 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.119Early AmniotesLiving amphibians and amniotes split from a common ancestor about 350 million years agoEarly amniotes were more tolerant of dry conditions than the first tetrapodsThe earliest amniotes were small predators with sharp teeth and long jaws 2014 Pearson Education, Inc.120

Figure 34.26 2014 Pearson Education, Inc.Figure 34.26 Artists reconstruction of Hylonomus, an early amniote121ReptilesThe reptile clade includes the tuataras, lizards, snakes, turtles, crocodilians, birds, and some extinct groupsReptiles have scales that create a waterproof barrierMost reptiles lay shelled eggs on land 2014 Pearson Education, Inc.122

Figure 34.UN07CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN07 In-text figure, Reptilia mini-tree, p. 729123

Figure 34.27 2014 Pearson Education, Inc.Figure 34.27 Hatching reptiles124Most reptiles are ectothermic, absorbing external heat as the main source of body heatEctotherms regulate their body temperature through behavioral adaptationsBirds are endothermic, capable of maintaining body temperature through metabolism 2014 Pearson Education, Inc.125The Origin and Evolutionary Radiation of ReptilesFossil evidence indicates that the earliest reptiles lived about 310 million years agoThe first major group to emerge were parareptiles, which were mostly large, stocky quadrupedal herbivores 2014 Pearson Education, Inc.126As parareptiles were dwindling, the diapsids were diversifyingThe diapsids consisted of two main lineages: the lepidosaurs and the archosaursThe lepidosaurs include tuataras, lizards, snakes, and extinct mososaursThe archosaur lineage produced the crocodilians, pterosaurs, and dinosaurs 2014 Pearson Education, Inc.127Pterosaurs were the first tetrapods to exhibit flightThe dinosaurs diversified into a vast range of shapes and sizesThey included bipedal carnivores called theropods, the group from which birds are descended 2014 Pearson Education, Inc.128Fossil discoveries and research have led to the conclusion that many dinosaurs were agile and fast movingPaleontologists have also discovered signs of parental care among dinosaursSome anatomical evidence supports the hypothesis that at least some dinosaurs were endotherms 2014 Pearson Education, Inc.129Dinosaurs, with the exception of birds, became extinct by the end of the CretaceousTheir extinction may have been partly caused by an asteroid 2014 Pearson Education, Inc.130TurtlesThe phylogenetic position of turtles remains uncertainAll turtles have a boxlike shell made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs 2014 Pearson Education, Inc.131

Figure 34.28Eastern box turtle (Terrapene carolina carolina)(b) Tuatara (Sphenodon punctatus)Waglers pit viper(Tropidolaemus wagleri)(a)(d)(e)American alligator (Alligatormississippiensis)(c)Australian thornydevil lizard(Moloch horridus) 2014 Pearson Education, Inc.Figure 34.28 Extant reptiles (other than birds)132

Figure 34.28a(a) Eastern box turtle (Terrapene carolina carolina) 2014 Pearson Education, Inc.Figure 34.28a Extant reptiles (other than birds) (part 1: Eastern box turtle)133

Figure 34.28b(b) Tuatara (Sphenodon punctatus) 2014 Pearson Education, Inc.Figure 34.28b Extant reptiles (other than birds) (part 2: tuatara)134

Figure 34.28c(c) Australian thorny devil lizard (Moloch horridus) 2014 Pearson Education, Inc.Figure 34.28c Extant reptiles (other than birds) (part 3: Australian thorny devil lizard)135

Figure 34.28d(d) Waglers pit viper (Tropidolaemus wagleri) 2014 Pearson Education, Inc.Figure 34.28d Extant reptiles (other than birds) (part 4: Waglers pit viper)136

Figure 34.28e(e) American alligator (Alligator mississippiensis) 2014 Pearson Education, Inc.Figure 34.28e Extant reptiles (other than birds) (part 5: American alligator)137Video: Galpagos Marine Iguana

2014 Pearson Education, Inc.Video: Snake Ritual Wrestling

2014 Pearson Education, Inc.Video: Galpagos Tortoise

2014 Pearson Education, Inc.Some turtles have adapted to deserts and others live entirely in ponds and riversThe largest turtles live in the seaMany species of sea turtles are endangered by accidental capture in fishing nets or development of beaches where they lay eggs

2014 Pearson Education, Inc.141LepidosaursOne surviving lineage of lepidosaurs is represented by two species of lizard-like reptiles called tuatarasLiving tuataras are restricted to small islands off the coast of New ZealandThey are threatened by introduced rats, which consume their eggs 2014 Pearson Education, Inc.142The other major living lineage of lepidosaurs consists of the squamates, the lizards and snakesSquamates are the most numerous and diverse reptiles, apart from birds

2014 Pearson Education, Inc.143Snakes are legless lepidosaurs that evolved from lizardsSnakes are carnivorous, and have adaptations to aid in capture and consumption of prey includingChemical sensorsHeat-detecting organsVenom Loosely articulated jawbones and elastic skin

2014 Pearson Education, Inc.144CrocodiliansCrocodilians (alligators and crocodiles) belong to an archosaur lineage that dates back to the late TriassicLiving crocodilians are restricted to warm regions 2014 Pearson Education, Inc.145BirdsBirds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight 2014 Pearson Education, Inc.146Derived Characters of BirdsMany characters of birds are adaptations that facilitate flightThe major adaptation is wings with keratin feathersOther adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth 2014 Pearson Education, Inc.147

Figure 34.29(a) Wing(b) Bone structureFinger 1PalmFinger 2Finger 3ShaftBarbBarbuleHook(c) Feather structureWristForearmShaftVane 2014 Pearson Education, Inc.Figure 34.29 Form fits function: the avian wing and feather148

Figure 34.29a(a) WingFinger 1PalmFinger 2Finger 3ShaftBarbBarbuleHookWristForearmShaftVane(b) Bone structure(c) Feather structure 2014 Pearson Education, Inc.Figure 34.29a Form fits function: the avian wing and feather (part 1: art)149

Figure 34.29b 2014 Pearson Education, Inc.Figure 34.29b Form fits function: the avian wing and feather (part 2: eagle)150

Figure 34.29c(b) Bone structure 2014 Pearson Education, Inc.Figure 34.29c Form fits function: the avian wing and feather (part 3: bone structure)151Video: Flapping Geese

2014 Pearson Education, Inc.Video: Soaring Hawk

2014 Pearson Education, Inc.Video: Swans Taking Flight

2014 Pearson Education, Inc.Flight enhances hunting and scavenging, escape from terrestrial predators, and migrationFlight requires a great expenditure of energy, acute vision, and fine muscle control 2014 Pearson Education, Inc.155The Origin of BirdsBirds probably descended from small theropods, a group of carnivorous dinosaursEarly feathers might have evolved for insulation, camouflage, or courtship display 2014 Pearson Education, Inc.156By 160 million years ago, feathered theropods had evolved into birdsArchaeopteryx remains the oldest bird known 2014 Pearson Education, Inc.157

Figure 34.30Toothed beakWing clawAirfoil wingwith contourfeathersLong tail withmany vertebrae 2014 Pearson Education, Inc.Figure 34.30 Was Archaeopteryx the first bird?158Living BirdsLiving birds belong to the clade NeornithesSeveral groups of birds are flightlessThe ratites, order StruthioniformesPenguins, order SphenisciformesCertain species of rails, ducks, and pigeons 2014 Pearson Education, Inc.159

Figure 34.31 2014 Pearson Education, Inc.Figure 34.31 An emu (Dromaius novaehollandiae), a flightless bird native to Australia160

Figure 34.32 2014 Pearson Education, Inc.Figure 34.32 A king penguin (Aptenodytes patagonicus) flying underwater161The demands of flight have rendered the general body form of many flying birds similar to one anotherBird species can be distinguished by characters including profile, color, flying style, behavior, beak shape, and foot structure 2014 Pearson Education, Inc.162

Figure 34.33 2014 Pearson Education, Inc.Figure 34.33 Hummingbird feeding while hovering163

Figure 34.34 2014 Pearson Education, Inc.Figure 34.34 A specialized beak164

Figure 34.34a 2014 Pearson Education, Inc.Figure 34.34a A specialized beak (part 1: greater flamingo)165

Figure 34.34b 2014 Pearson Education, Inc.Figure 34.34b A specialized beak (part 2: greater flamingo beak)166

Figure 34.35 2014 Pearson Education, Inc.Figure 34.35 Feet adapted to perching167Concept 34.6: Mammals are amniotes that have hair and produce milkMammals, class Mammalia, are represented by more than 5,300 species 2014 Pearson Education, Inc.168

Figure 34.UN08CephalochordataUrochordataMyxiniPetromyzontidaChondrichthyesActinopterygiiActinistiaDipnoiAmphibiaReptiliaMammalia 2014 Pearson Education, Inc.Figure 25.UN08 In-text figure, Mammalia mini-tree, p. 735169Derived Characters of MammalsMammals haveMammary glands, which produce milkHair A high metabolic rate, due to endothermyA larger brain than other vertebrates of equivalent sizeDifferentiated teeth 2014 Pearson Education, Inc.170Early Evolution of MammalsMammals are synapsidsIn 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.171

Figure 34.36KeyArticularQuadrateDentarySquamosalEardrumMiddle earInner earStapesIncus (quadrate) Malleus(articular)SoundPresent-day mammalPresent-day reptile(b) Articular and quadrate bones in the middle ear SoundEardrumMiddle earStapesInner ear(a) Articular and quadrate bones in the jawBiarmosuchus,an extinctsynapsidTemporalfenestraJaw joint 2014 Pearson Education, Inc.Figure 34.36 The evolution of the mammalian ear bones172By the early Cretaceous, the three living lineages of mammals emerged: monotremes, marsupials, and eutheriansMammals did not undergo a significant adaptive radiation until after the Cretaceous 2014 Pearson Education, Inc.173MonotremesMonotremes are a small group of egg-laying mammals consisting of echidnas and the platypus

2014 Pearson Education, Inc.174

Figure 34.37 2014 Pearson Education, Inc.Figure 34.37 Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme175

Figure 34.37a 2014 Pearson Education, Inc.Figure 34.37a Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme (part 1: echidna adult)176

Figure 34.37b 2014 Pearson Education, Inc.Figure 34.37b Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme (part 2: echidna egg)177MarsupialsMarsupials include opossums, kangaroos, and koalasThe embryo develops within a placenta in the mothers uterusA marsupial is born very early in its developmentIt completes its embryonic development while nursing in a maternal pouch called a marsupium 2014 Pearson Education, Inc.178

Figure 34.38(a) A young brushtail possum(b) A greater bilby 2014 Pearson Education, Inc.Figure 34.38 Australian marsupials179

Figure 34.38a(a) A young brushtail possum 2014 Pearson Education, Inc.Figure 34.38a Australian marsupials (part 1: brushtail possum)180

Figure 34.38b(b) A greater bilby 2014 Pearson Education, Inc.Figure 34.38b Australian marsupials (part 2: greater bilby)181In some species, such as the bandicoot, the marsupium opens to the rear of the mothers bodyIn Australia, convergent evolution has resulted in a diversity of marsupials that resemble the eutherians in other parts of the world

2014 Pearson Education, Inc.182

Figure 34.39Marsupial mammalsEutherian mammalsPlantigaleMarsupialmoleSugargliderWombatTasmaniandevilKangarooDeer mouseMoleFlyingsquirrelWoodchuckWolverinePatagoniancavy 2014 Pearson Education, Inc.Figure 34.39 Convergent evolution of marsupials and eutherians (placental mammals)183

Figure 34.39aMarsupial mammalsEutherian mammalsPlantigaleMarsupialmoleDeer mouseMoleSugargliderFlyingsquirrel 2014 Pearson Education, Inc.Figure 34.39a Convergent evolution of marsupials and eutherians (placental mammals) (part 1)184

Figure 34.39bWombatTasmaniandevilKangarooWoodchuckWolverinePatagoniancavyMarsupial mammalsEutherian mammals 2014 Pearson Education, Inc.Figure 34.39b Convergent evolution of marsupials and eutherians (placental mammals) (part 2)185Eutherians (Placental Mammals)Compared with marsupials, eutherians have a more complex placentaYoung eutherians complete their embryonic development within a uterus, joined to the mother by the placentaMolecular and morphological data give conflicting dates on the diversification of eutherians 2014 Pearson Education, Inc.186

Figure 34.40aANCESTRALMAMMALMonotremataMarsupialiaProboscideaSireniaTubulidentataHyracoideaAfrosoricidaMacroscelideaXenarthraRodentiaLagomorphaPrimatesDermopteraScandentiaCarnivoraCetartiodactylaPerissodactylaChiropteraEulipotyphlaPholidotaMonotremes(5 species)Marsupials(324 species)Eutherians(5,010 species) 2014 Pearson Education, Inc.Figure 34.40a Exploring mammalian diversity (part 1: phylogenetic tree)187

Figure 34.40aaANCESTRALMAMMALMonotremataMarsupialiaProboscideaSireniaTubulidentataHyracoideaAfrosoricidaMacroscelideaMonotremes(5 species)Marsupials(324 species)Eutherians(5,010 species) 2014 Pearson Education, Inc.Figure 34.40aa Exploring mammalian diversity (part 1a: phylogenetic tree)188

Figure 34.40abXenarthraRodentiaLagomorphaPrimatesDermopteraScandentiaCarnivoraCetartiodactylaPerissodactylaChiropteraEulipotyphlaPholidotaEutherians(5,010 species)ProboscideaSireniaTubulidentataHyracoideaAfrosoricidaMacroscelidea 2014 Pearson Education, Inc.Figure 34.40ab Exploring mammalian diversity (part 1b: phylogenetic tree)189

Figure 34.40bOrdersand ExamplesMainCharacteristicsOrdersand ExamplesMainCharacteristicsMonotremataPlatypuses,echidnasProboscideaElephantsEchidnaAfrican elephantSireniaManatees,dugongsManateeXenarthraSloths,anteaters,armadillosTamanduaJackrabbitCoyoteLagomorphaRabbits, hares,picasCarnivoraDogs, wolves,bears, cats,weasels, otters,seals, walrusesBighorn sheepPacific white-sided porpoiseCetartiodactylaArtiodactyls:sheep, pigs,cattle, deer,giraffesCetaceans:whales,dolphins,porpoisesAquatic; streamlinedbody; paddle-likeforelimbs and no hindlimbs; thick layer ofinsulating blubber;carnivorousHooves with an evennumber of toes on eachfoot; herbivorousSharp, pointed canineteeth and molars forshearing; carnivorousChisel-like incisors;hind legs longer thanforelegs and adaptedfor running and jump-ing; herbivorousReduced teeth or noteeth; herbivorous(sloths) or carnivorous(anteaters, armadillos)Aquatic; finlike fore-limbs and no hindlimbs; herbivorousLong, muscular trunk;thick, loose skin; upperincisors elongatedas tusksLay eggs; no nipples;young suck milk fromfur of motherCompletes embryonicdevelopment in pouchon mothers bodyTeeth consisting ofmany thin tubescemented together;eats ants and termitesShort legs; stumpytail; herbivorous;complex, multi-chambered stomachChisel-like, continuouslygrowing incisors worndown by gnawing;herbivorousOpposable thumbs;forward-facing eyes;well-developed cerebralcortex; omnivorousHooves with an oddnumber of toes oneach foot; herbivorousAdapted for flight;broad skinfold thatextends from elongatedfingers to body andlegs; carnivorous orherbivorousEat mainly insectsand other smallinvertebratesStar-nosedmoleFrog-eating batIndian rhinocerosGolden liontamarinRed squirrelRock hyraxAardvarkKoalaMarsupialiaKangaroos,opossums,koalasAardvarksTubulidentataHyracoideaHyraxesRodentiaSquirrels,beavers, rats, porcupines,mice PrimatesLemurs, monkeys,chimpanzees,gorillas, humansHorses,zebras, tapirs,rhinocerosesPerissodactylaChiropteraBatsCoreinsectivores:some moles, some shrewsEulipotyphla 2014 Pearson Education, Inc.Figure 34.40b Exploring mammalian diversity (part 2: orders and examples)190

Figure 34.40baOrders and ExamplesMain CharacteristicsPlatypuses,echidnasEchidnaLay eggs; no nipples;young suck milk fromfur of motherCompletes embryonicdevelopment in pouchon mothers bodyKoalaMarsupialiaKangaroos,opossums,koalasMonotremata 2014 Pearson Education, Inc.Figure 34.40ba Exploring mammalian diversity (part 2a: orders and examples)191

Figure 34.40bbOrders and ExamplesMain CharacteristicsElephantsAfrican elephantSireniaManatees,dugongsManateeAquatic; finlike fore-limbs and no hindlimbs; herbivorousLong, muscular trunk;thick, loose skin; upperincisors elongatedas tusksProboscideaTeeth consisting ofmany thin tubescemented together;eats ants and termitesShort legs; stumpytail; herbivorous;complex, multi-chambered stomachRock hyraxAardvarkAardvarksTubulidentataHyracoideaHyraxes 2014 Pearson Education, Inc.Figure 34.40bb Exploring mammalian diversity (part 2b: orders and examples)192

Figure 34.40bcXenarthraSloths,anteaters,armadillosTamanduaJackrabbitLagomorphaRabbits, hares,picasChisel-like incisors;hind legs longer thanforelegs and adaptedfor running and jump-ing; herbivorousReduced teeth or noteeth; herbivorous(sloths) or carnivorous(anteaters, armadillos)Chisel-like, continuouslygrowing incisors worndown by gnawing;herbivorousOpposable thumbs;forward-facing eyes;well-developed cerebralcortex; omnivorousGolden liontamarinRed squirrelRodentiaSquirrels,beavers, rats, porcupines,mice PrimatesLemurs, monkeys,chimpanzees,gorillas, humansOrders and ExamplesMain Characteristics 2014 Pearson Education, Inc.Figure 34.40bc Exploring mammalian diversity (part 2c: orders and examples)193

Figure 34.40bdOrders and ExamplesMain CharacteristicsCoyoteDogs, wolves,bears, cats,weasels, otters,seals, walrusesBighorn sheepPacific white-sided porpoiseCetartiodactylaArtiodactyls:sheep, pigs,cattle, deer,giraffesCetaceans:whales,dolphins,porpoisesAquatic; streamlinedbody; paddle-likeforelimbs and no hindlimbs; thick layer ofinsulating blubber;carnivorousHooves with an evennumber of toes on eachfoot; herbivorousSharp, pointed canineteeth and molars forshearing; carnivorousCarnivora 2014 Pearson Education, Inc.Figure 34.40bd Exploring mammalian diversity (part 2d: orders and examples)194

Figure 34.40beOrders and ExamplesMain CharacteristicsHooves with an oddnumber of toes oneach foot; herbivorousAdapted for flight;broad skinfold thatextends from elongatedfingers to body andlegs; carnivorous orherbivorousEat mainly insectsand other smallinvertebratesStar-nosedmoleFrog-eating batIndian rhinocerosHorses, zebras, tapirs,rhinocerosesPerissodactylaChiropteraBatsCoreinsectivores:some moles, some shrewsEulipotyphla 2014 Pearson Education, Inc.Figure 34.40be Exploring mammalian diversity (part 2e: orders and examples)195Video: Bat Licking Nectar

2014 Pearson Education, Inc.Video: Bat Pollinating Agave Plant

2014 Pearson Education, Inc.Video: Galpagos Sea Lion

2014 Pearson Education, Inc.Video: Wolves Agonistic Behavior

2014 Pearson Education, Inc.Video: Shark Eating a Seal

2014 Pearson Education, Inc.PrimatesThe mammalian order Primates includes lemurs, tarsiers, monkeys, and apesHumans are members of the ape group 2014 Pearson Education, Inc.201Derived Characters of PrimatesMost primates have hands and feet adapted for grasping, and flat nails 2014 Pearson Education, Inc.202Other derived characters of primates A large brain and short jawsForward-looking eyes close together on the face, providing depth perceptionComplex social behavior and parental careA fully opposable thumb (in monkeys and apes) 2014 Pearson Education, Inc.203Living PrimatesThere are three main groups of living primatesLemurs, lorises, and bush babies TarsiersAnthropoids (monkeys and apes) 2014 Pearson Education, Inc.204

Figure 34.41 2014 Pearson Education, Inc.Figure 34.41 Verreauxs sifakas (Propithecus verreauxi), a type of lemur205The 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.206

Figure 34.42ANCESTRALPRIMATELemurs, lorises,and bush babiesTarsiersNew World monkeysOld World monkeysGibbonsOrangutansGorillasHumansChimpanzeesand bonobosAnthropoids706050403020100Time (millions of years ago) 2014 Pearson Education, Inc.Figure 34.42 A phylogenetic tree of primates207The first monkeys evolved in the Old World (Africa and Asia)In the New World (South America), monkeys first appeared roughly 25 million years agoNew World and Old World monkeys underwent separate adaptive radiations during their many millions of years of separation 2014 Pearson Education, Inc.208

Figure 34.43New World monkey:spider monkeyOld World monkey:macaque(b)(a) 2014 Pearson Education, Inc.Figure 34.43 New World monkeys and Old World monkeys209

Figure 34.43aNew World monkey:spider monkey(a) 2014 Pearson Education, Inc.Figure 34.43a New World monkeys and Old World monkeys (part 1: spider monkey, a New World monkey)210

Figure 34.43bOld World monkey:macaque(b) 2014 Pearson Education, Inc.Figure 34.43b New World monkeys and Old World monkeys (part 2: macaque, an Old World monkey)211The other group of anthropoids consists of primates informally called apesThis group includes gibbons, orangutans, gorillas, chimpanzees, bonobos, and humansApes diverged from Old World monkeys about 2530 million years ago 2014 Pearson Education, Inc.212

Figure 34.44(a) Gibbon(b) Orangutan(e) Bonobos(d) Chimpanzees(c) Gorilla 2014 Pearson Education, Inc.Figure 34.44 Nonhuman apes213

Figure 34.44a(a) Gibbon 2014 Pearson Education, Inc.Figure 34.44a Nonhuman apes (part 1: gibbon)214

Figure 34.44b(b) Orangutan 2014 Pearson Education, Inc.Figure 34.44b Nonhuman apes (part 2: orangutan)215

Figure 34.44c(c) Gorilla 2014 Pearson Education, Inc.Figure 34.44c Nonhuman apes (part 3: gorilla)216

Figure 34.44d(d) Chimpanzees 2014 Pearson Education, Inc.Figure 34.44d Nonhuman apes (part 4: chimpanzees)217

Figure 34.44e(e) Bonobos 2014 Pearson Education, Inc.Figure 34.44e Nonhuman apes (part 5: bonobos)218Video: Gibbons Brachiating

2014 Pearson Education, Inc.Video: Chimp Agonistic Behavior

2014 Pearson Education, Inc.Video: Chimp Cracking Nut

2014 Pearson Education, Inc.Concept 34.7: Humans are mammals that have a large brain and bipedal locomotionThe 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.222Derived Characters of HumansA number of characters distinguish humans from other apesUpright posture and bipedal locomotionLarger brains capable of language, symbolic thought, artistic expression, the manufacture and use of complex toolsReduced jawbones and jaw musclesShorter digestive tract 2014 Pearson Education, Inc.223The human and chimpanzee genomes are 99% identicalChanges in regulatory genes can have large effects 2014 Pearson Education, Inc.224The Earliest HomininsThe study of human origins is known as paleoanthropologyHominins (formerly called hominids) are more closely related to humans than to chimpanzeesPaleoanthropologists have discovered fossils of about 20 species of extinct hominins 2014 Pearson Education, Inc.225

Figure 34.45ParanthropusboiseiAustralopithecusafricanusAustralopithecusgarhiKenyanthropusplatyopsAustralo-pithecusanamensisAustralopithecusafarensisArdipithecus ramidusSahelanthropustchadensisOrrorin tugenensisHomohabilisHomorudolfensisHomo erectusHomo ergasterHomo neanderthalensisParanthropusrobustusHomo sapiens00.51.01.52.02.53.03.54.04.55.05.56.06.57.0Millions of years ago? 2014 Pearson Education, Inc.Figure 34.45 A timeline for selected hominin species226

Figure 34.45a0.5Millions of years ago1.01.52.02.53.03.50ParanthropusboiseiHomo ergasterHomoneander-thalensisParanthropusrobustusHomo sapiensAustralopithecusgarhiAustralopithecusafricanusHomo erectusHomo rudolfensisHomo habilis? 2014 Pearson Education, Inc.Figure 34.45a A timeline for selected hominin species (part 1: 3.5 mya to present)227

Figure 34.45b2.5Millions of years ago3.03.54.04.55.05.56.06.57.0KenyanthropusplatyopsAustralo-pithecusanamensisAustralopithecusafarensisArdipithecus ramidusSahelanthropustchadensisOrrorin tugenensis 2014 Pearson Education, Inc.Figure 34.45b A timeline for selected hominin species (part 2: 7.0 mya to 3.5 mya)228The oldest fossil evidence of hominins dates back to 6.5 million years agoEarly hominins show evidence of small brains and increasing bipedalism 2014 Pearson Education, Inc.229

Figure 34.46 2014 Pearson Education, Inc.Figure 34.46 The skeleton of Ardi, a 4.4-million-year-old hominin, Ardipithecus ramidus230Misconception: Early hominins were chimpanzeesCorrection: Hominins and chimpanzees shared a common ancestorMisconception: Human evolution is like a ladder leading directly to Homo sapiensCorrection: Hominin evolution included many branches or coexisting species, though only humans survive today 2014 Pearson Education, Inc.231AustralopithsAustralopiths are a paraphyletic assemblage of hominins living between 4 and 2 million years agoSome species, such as Australopithecus afarensis walked fully erect 2014 Pearson Education, Inc.232

Figure 34.47(a) The Laetoli footprints(b) An artists reconstruction of A. afarensis 2014 Pearson Education, Inc.Figure 34.47 Evidence that hominins walked upright 3.5 million years ago233

Figure 34.47a(a) The Laetoli footprints 2014 Pearson Education, Inc.Figure 34.47a Evidence that hominins walked upright 3.5 million years ago (part 1: photo)234

Figure 34.47b(b) An artists reconstruction of A. afarensis 2014 Pearson Education, Inc.Figure 34.47b Evidence that hominins walked upright 3.5 million years ago (part 2: artists reconstruction)235Robust australopiths had sturdy skulls and powerful jawsGracile australopiths were more slender and had lighter jaws 2014 Pearson Education, Inc.236BipedalismHominins began to walk long distances on two legs about 1.9 million years agoBipedal walking was energy efficient in the arid environments inhabited by hominins at the time 2014 Pearson Education, Inc.237Tool UseThe oldest evidence of tool use, cut marks on animal bones, is 2.5 million years oldFossil evidence indicates tool use may have originated prior to the evolution of large brains 2014 Pearson Education, Inc.238Early HomoThe earliest fossils placed in our genus Homo are those of Homo habilis, ranging in age from about 2.4 to 1.6 million yearsStone tools have been found with H. habilis, giving this species its name, which means handy man 2014 Pearson Education, Inc.239Homo ergaster was the first fully bipedal, large-brained hominidThe species existed between 1.9 and 1.5 million years agoHomo ergaster shows a significant decrease in sexual dimorphism (a size difference between sexes) compared with its ancestors 2014 Pearson Education, Inc.240Homo ergaster fossils were previously assigned to Homo erectus; most paleoanthropologists now recognize these as separate species 2014 Pearson Education, Inc.241

Figure 34.48 2014 Pearson Education, Inc.Figure 34.48 Fossil of Homo ergaster242Homo erectus originated in Africa by 1.8 million years agoIt was the first hominin to leave Africa 2014 Pearson Education, Inc.243NeanderthalsNeanderthals, Homo neanderthalensis, lived in Europe and the Near East from 350,000 to 28,000 years agoThey were thick-boned with a larger brain, they buried their dead, and they made hunting toolsRecent genetic analysis indicates that gene flow occurred between Neanderthals and Homo sapiens 2014 Pearson Education, Inc.244

Figure 34.49These relatively high bars indicate that theNeanderthal genome was more similar togenomes of non-Africans than of Africans.Africans toAfricansNon-Africans to AfricansNon-Africans toNon-AfricansPopulations being compared in relation to NeanderthalsGenetic similarity index (D)76543210Results 2014 Pearson Education, Inc.Figure 34.49 Inquiry: Did gene flow occur between Neanderthals and humans?245Homo SapiensHomo sapiens appeared in Africa by 195,000 years agoAll living humans are descended from these African ancestors 2014 Pearson Education, Inc.246

Figure 34.UN10A 160,000-year-old fossil of Homo sapiens. 2014 Pearson Education, Inc.Figure 25.UN10 In-text figure, Homo sapiens skull fossil, p. 747247The oldest fossils of Homo sapiens outside Africa date back about 115,000 years and are from the Middle EastHumans first arrived in the New World sometime before 15,000 years agoIn 2004, 18,000-year-old fossils were found in Indonesia, and a new small hominin was named: Homo floresiensis 2014 Pearson Education, Inc.248Homo sapiens were the first group to show evidence of symbolic and sophisticated thoughtIn 2002, a 77,000-year-old artistic carving was found in South Africa 2014 Pearson Education, Inc.249

Figure 34.50 2014 Pearson Education, Inc.Figure 34.50 Art, a human hallmark250

Figure 34.UN09aHominin SpeciesArdipithecusramidusAustralopithecusafarensisHomo habilisHomo ergasterHomo erectusHomo heidelbergensisHomo neanderthalensisHomo sapiens0.00.10.51.21.61.93.44.43253755508501,0001,2001,4001,350Mean age(millions ofyears; x)Mean BrainVolume(cm3; y)xixyiyxix)(yiy)( 2014 Pearson Education, Inc.Figure 25.UN09a Skills exercise: determining the equation of a regression line (part 1)251

Figure 34.UN09b 2014 Pearson Education, Inc.Figure 25.UN09b Skills exercise: determining the equation of a regression line (part 2)252

Figure 34.UN11CladeDescriptionCephalochordata(lancelets)Basal chordates; marine suspension feeders thatexhibit four key derived characters of chordatesMarine suspension feeders; larvae display thederived traits of chordatesJawless marine vertebrates with reduced vertebrae;have head that includes a skull and brain, eyes, andother sensory organs Jawless aquatic vertebrates with reducedvertebrae; typically feed by attaching to a livefish and ingesting its blood Aquatic gnathostomes; have cartilaginous skeleton,a derived trait formed by the reduction of anancestral mineralized skeleton Aquatic gnathostomes; have bony skeleton andmaneuverable fins supported by rays Ancient lineage of aquatic lobe-fins still survivingin Indian OceanFreshwater lobe-fins with both lungs and gills;sister group of tetrapods Have four limbs descended from modified fins; mosthave moist skin that functions in gas exchange; manylive both in water (as larvae) and on land (as adults) One of two groups of living amniotes; have amnioticeggs and rib cage ventilation, key adaptations for lifeon landEvolved from synapsid ancestors; include egg-layingmonotremes (echidnas, platypus); pouched marsupials(such as kangaroos, opossums); and eutherians(placental mammals, such as rodents, primates) Urochordata(tunicates) Myxini (hagfishes)Petromyzontida(lampreys) Chondrichthyes(sharks, rays,skates, ratfishes) Actinopterygii(ray-finned fishes) Actinistia(coelacanths) Dipnoi(lungfishes) Amphibia(salamanders,frogs, caecilians) Reptilia (tuataras, lizardsand snakes, turtles,crocodilians,birds) Mammalia(monotremes,marsupials,eutherians) Amniotes: amniotic egg,rib cage ventilationTetrapods: four limbs, neck,fused pelvic girdleLobe-fins: muscular fins or limbsOsteichthyans: bony skeletonGnathostomes: hinged jaws, four sets of Hox genesVertebrates: Hox genes duplication, backbone of vertebraeChordates: notochord; dorsal, hollow nerve cord; pharyngeal slits; post-anal tail 2014 Pearson Education, Inc.Figure 25.UN11 Summary of key concepts: clade descriptions253

Figure 34.UN11aCladeDescriptionBasal chordates; marine suspension feeders thatexhibit four key derived characters of chordatesMarine suspension feeders; larvae display thederived traits of chordatesJawless marine vertebrates with reduced vertebrae;have head that includes a skull and brain, eyes, andother sensory organs Jawless aquatic vertebrates with reducedvertebrae; typically feed by attaching to a livefish and ingesting its blood Aquatic gnathostomes; have cartilaginous skeleton,a derived trait formed by the reduction of anancestral mineralized skeleton Aquatic gnathostomes; have bony skeleton andmaneuverable fins supported by rays Ancient lineage of aquatic lobe-fins still survivingin Indian OceanFreshwater lobe-fins with both lungs and gills;sister group of tetrapods Cephalochordata(lancelets)Urochordata(tunicates) Myxini (hagfishes)Petromyzontida(lampreys) Chondrichthyes(sharks, rays,skates, ratfishes) Actinopterygii(ray-finned fishes) Actinistia(coelacanths) Dipnoi(lungfishes) 2014 Pearson Education, Inc.Figure 25.UN11a Summary of key concepts: clade descriptions (part 1)254

Figure 34.UN11bHave four limbs descended from modified fins; mosthave moist skin that functions in gas exchange; manylive both in water (as larvae) and on land (as adults) One of two groups of living amniotes; have amnioticeggs and rib cage ventilation, key adaptations for lifeon landEvolved from synapsid ancestors; include egg-layingmonotremes (echidnas, platypus); pouched marsupials(such as kangaroos, opossums); and eutherians(placental mammals, such as rodents, primates) Amphibia(salamanders,frogs, caecilians) Reptilia (tuataras, lizardsand snakes, turtles,crocodilians,birds) Mammalia(monotremes,marsupials,eutherians) CladeDescription 2014 Pearson Education, Inc.Figure 25.UN11b Summary of key concepts: clade descriptions (part 2)255

Figure 34.UN12DeviationfromExpectedBrain Size*MortalityRate0.90.70.50.90.40.70.80.40.80.30.60.60.30.63.23.02.32.01.31.20.70.30.01.0D. Sol et al., Big-brained birds survive better in nature, Proceedings of the RoyalSociety B 274:763769 (2007).* Values < 0 indicate brain sizes smaller than expected; values > 0 indicate sizeslarger than expected.1.82.02.12.4 2014 Pearson Education, Inc.Figure 25.UN12 Test your understanding, question 8 (brain size)256

Figure 34.UN13 2014 Pearson Education, Inc.Figure 25.UN13 Test your understanding, question 10 (vertebrate with hair)257