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Animals: The Vertebrates Chapter 26. Something Old, Something New Every animal is a combination of traits Every animal is a combination of traits Some.

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Presentation on theme: "Animals: The Vertebrates Chapter 26. Something Old, Something New Every animal is a combination of traits Every animal is a combination of traits Some."— Presentation transcript:

1 Animals: The Vertebrates Chapter 26

2 Something Old, Something New Every animal is a combination of traits Every animal is a combination of traits Some traits are conserved from remote ancestors Some traits are conserved from remote ancestors Other traits are unique to its branch of the family tree Other traits are unique to its branch of the family tree

3 Chordate Features Deuterostomes Deuterostomes All share four features: All share four features: –Notochord supports body –Nervous system develops from dorsal nerve cord –Embryos have pharynx with slits –Embryos have tail that extends past anus

4 Chordate Groups Urochordata Urochordata –Salps and tunicates Cephalochordata Cephalochordata –Lancelets Craniates Craniates –Fishes, amphibians, reptiles, birds, mammals

5 Tunicates (Urochordates) Larva is free-swimming Larva is free-swimming Adult is sessile and baglike with no coelom Adult is sessile and baglike with no coelom Both stages are filter feeders Both stages are filter feeders Pharynx serves in both feeding and respiration Pharynx serves in both feeding and respiration

6 Tunicate Life History Larva undergoes metamorphosis to adult form nerve cordnotochord gut Tunicate larva oral opening atrial opening pharynx with gill slits Tunicate adult pharynx Figure 26.3 Page 446

7 Lancelets (Cephalochordates) Fish-shaped filter feeders Fish-shaped filter feeders Simple brain Simple brain Segmented muscles Segmented muscles Chordate characteristics of adult: Chordate characteristics of adult: –Notochord lies under dorsal nerve cord –Pharynx has gill slits –Tail extends past anus

8 Lancelet Body Plan dorsal, tubular nerve cord notochord pharynx with gill slits tail extending past anus anus pore of atrial cavity hindgut gonadaorta midgut segmented muscles tentaclelike structures around mouth Figure 26.4a Page 447

9 Early Craniates Reconstruction of one of the earliest known craniates Do not post on Internet Brain inside chamber of cartilage or bone Brain inside chamber of cartilage or bone Arose before 530 million years ago Arose before 530 million years ago Resemble lancelets, lamprey larva Resemble lancelets, lamprey larva Figure 26.4 Page 447

10 Trends in the Evolution of Vertebrates Shift from notochord to vertebral column Shift from notochord to vertebral column Nerve cord expanded into brain Nerve cord expanded into brain Evolution of jaws Evolution of jaws Paired fins evolved, gave rise to limbs Paired fins evolved, gave rise to limbs Gills evolved, gave rise to lungs Gills evolved, gave rise to lungs

11 Evolution of Jaws First fishes lacked jaws First fishes lacked jaws Jaws are modifications of anterior gill supports Jaws are modifications of anterior gill supports Figure 26.5 Page 448 supporting structures gill slit jaw spiracle jaw support jaw Early jawless fish (agnathan) Early jawed fish (placoderm) Modern jawed fish (shark)

12 Existing Jawless Fishes Cylindrical body Cylindrical body Cartilaginous skeleton Cartilaginous skeleton No paired fins No paired fins gill openings (seven pairs) Lamprey Hagfish tentaclesgill slits (twelve pairs)mucous glands

13 Jawed Fishes Most diverse and numerous group of vertebrates Most diverse and numerous group of vertebrates Two classes: Two classes: –Chondrichthyes (cartilaginous fishes) –Osteichthyes (bony fishes)

14 Cartilaginous Fishes: Class Chondrichthyes Most are marine predators Most are marine predators Cartilaginous skeleton Cartilaginous skeleton Main groups: Main groups: –Skates and rays –Sharks –Chimaeras (ratfishes)

15 Bony Fishes: Class Osteichthyes Includes 96 percent of living fish species Includes 96 percent of living fish species Three subclasses: Three subclasses: –Ray-finned fishes –Lobe-finned fishes –Lung fishes

16 Body Plan of a Bony Fish muscle segments fin supports brain olfactory bulb heart liver gallbladder stomach intestineswim bladder kidney anus urinary bladder Figure 26.9b Page 451

17 Lobe-Finned Fishes Coelocanths Coelocanths Lunglike sacs do not function in gas exchange Lunglike sacs do not function in gas exchange

18 Lungfishes Have gills and one lung or a pair Have gills and one lung or a pair Must surface to gulp air Must surface to gulp air Do not post on Internet Figure 26.9f Page 451

19 Early Amphibians Fishlike skull and tail Fishlike skull and tail Four limbs with digits Four limbs with digits Short neck Short neck Acanthostega Ichthyostega Do not post on Internet Figure 26.10a Page 452

20 Modern Amphibians All require water at some stage in the life cycle; most lay eggs in water All require water at some stage in the life cycle; most lay eggs in water Lungs are less efficient than those of other vertebrates Lungs are less efficient than those of other vertebrates Skin serves as respiratory organ Skin serves as respiratory organ

21 From Fins to Limbs Genetic enhancer controls genes involved in formation of digits on limb bones Genetic enhancer controls genes involved in formation of digits on limb bones Change in a single master gene can drastically alter morphology Change in a single master gene can drastically alter morphology

22 Living Amphibian Groups Frogs and toads Frogs and toads Salamanders Salamanders Caecilians Caecilians

23 Rise of Amniotes Arose during Carboniferous Arose during Carboniferous Adaptations to life on land Adaptations to life on land –Tough, scaly skin –Internal fertilization –Amniote eggs –Water-conserving kidneys

24 Adaptive Radiation Produced numerous lineages Produced numerous lineages Extinct groups include: Extinct groups include: –Therapsids (ancestors of mammals) –Marine plesiosaurs & ichthyosaurs –Dinosaurs and pterosaurs

25 Living Reptiles Not a monophyletic group CrocodiliansTurtlesTuataras Snakes and lizards

26 Evolutionary History of Amniotes lizards snakes tuataras birds archosaurs dinosaurs pterosaurs crocodilians ichthyosaurs plesiosaurs turtles synapsids therapsids anapsids (mammals) stem reptiles Paleozoic era Mesozoic era CarboniferousPermianTriassicJurassicCretaceous Figure 26.14 Page 455

27 Crocodile Body Plan Figure 26.13c Page 454 snout olfactory lobe spinal cord vertebral column gonad kidney cloaca intestine stomach liver heart esophagus hindbrain, midbrain, forebrain

28 Turtles Armorlike shell Armorlike shell Horny plates instead of teeth Horny plates instead of teeth Lay eggs on land Lay eggs on land Figure 26.15 Page 456

29 Lizards and Snakes Largest order (95 percent of living reptiles) Largest order (95 percent of living reptiles) Most lizards are insectivores with small peglike teeth Most lizards are insectivores with small peglike teeth All snakes are carnivores with highly movable jaws All snakes are carnivores with highly movable jaws hollow fang venom gland Figure 26.15d Page 457

30 Tuataras Only two living species Only two living species Live on islands off coast of New Zealand Live on islands off coast of New Zealand Look like lizards, but resemble amphibians in some aspects of their brain and in their way of walking Look like lizards, but resemble amphibians in some aspects of their brain and in their way of walking

31 Birds Diverged from small theropod dinosaurs during the Mesozoic Diverged from small theropod dinosaurs during the Mesozoic Feathers are a unique trait Feathers are a unique trait –Derived from reptilian scales –Serve in insulation and flight

32 Amniote Egg yolk sacembryo chorion amnion albumin hardened shell allantois Figure 26.16a Page 458

33 Adapted for Flight Four-chambered heart Four-chambered heart Highly efficient respiratory system Highly efficient respiratory system Lightweight bones with air spaces Lightweight bones with air spaces Powerful muscles attach to the keel Powerful muscles attach to the keel Figure 26.17 Page 458

34 Mammals: Phylum Mammalia Hair Hair Mammary glands Mammary glands Distinctive teeth Distinctive teeth Highly developed brain Highly developed brain Extended care for the young Extended care for the young Figure 26.19c Page 460

35 Mammal Origins & Radiation During Triassic, synapsids gave rise to therapsids (ancestors of mammals) During Triassic, synapsids gave rise to therapsids (ancestors of mammals) By Jurassic, mouselike therians had evolved By Jurassic, mouselike therians had evolved Therians coexisted with dinosaurs through Cretaceous Therians coexisted with dinosaurs through Cretaceous Radiated after dinosaur extinction Radiated after dinosaur extinction

36 Three Mammalian Lineages Monotremes Monotremes –Egg-laying mammals Marsupials Marsupials –Pouched mammals Eutherians Eutherians –Placental mammals

37 Role of Geologic Change Monotremes and marsupials evolved while Pangea was intact Monotremes and marsupials evolved while Pangea was intact Placental mammals evolved after what would become Australia had split off Placental mammals evolved after what would become Australia had split off No placental mammals in Australia No placental mammals in Australia Elsewhere, placental mammals replaced most marsupials Elsewhere, placental mammals replaced most marsupials

38 Living Monotremes Three species Three species –Duck-billed platypus –Two kinds of spiny anteater All lay eggs All lay eggs

39 Living Marsupials Most of the 260 species are native to Australia and nearby islands Most of the 260 species are native to Australia and nearby islands Only the opossums are found in North America Only the opossums are found in North America Young are born in an undeveloped state and complete development in a permanent pouch on mother Young are born in an undeveloped state and complete development in a permanent pouch on mother

40 Living Placental Mammals Most diverse mammalian group Most diverse mammalian group Young develop in mother’s uterus Young develop in mother’s uterus Placenta composed of maternal and fetal tissues; nourishes fetus, delivers oxygen, and removes wastes Placenta composed of maternal and fetal tissues; nourishes fetus, delivers oxygen, and removes wastes Placental mammals develop more quickly than marsupials Placental mammals develop more quickly than marsupials

41 Earliest Primates Primates evolved more than 60 million years ago during the Paleocene Primates evolved more than 60 million years ago during the Paleocene First primates resembled tree shrews First primates resembled tree shrews –Long snouts –Poor daytime vision

42 From Primates to Humans “Uniquely” human traits evolved through modification of traits that evolved earlier, in ancestral forms

43 Hominoids Apes, humans, and extinct species of their lineages Apes, humans, and extinct species of their lineages In biochemistry and body form, humans are closer to apes than to monkeys In biochemistry and body form, humans are closer to apes than to monkeys Hominids Hominids –Subgroup that includes humans and extinct humanlike species

44 Trends in Lineage Leading to Humans Less reliance on smell, more on vision Less reliance on smell, more on vision Skeletal changes to allow bipedalism Skeletal changes to allow bipedalism Modifications of hand allow fine movements Modifications of hand allow fine movements Bow-shaped jaw and smaller teeth Bow-shaped jaw and smaller teeth Longer lifespan and period of dependency Longer lifespan and period of dependency

45 Adaptations to an Arboreal Lifestyle Better daytime vision Better daytime vision Shorter snout Shorter snout Larger brain Larger brain Forward-directed eyes Forward-directed eyes Capacity for grasping motions Capacity for grasping motions

46 The First Hominoids The First Hominoids Appeared during Miocene Appeared during Miocene Arose in Central Africa Arose in Central Africa Spread through Africa, Asia, Europe Spread through Africa, Asia, Europe Climate was changing, becoming cooler and drier Climate was changing, becoming cooler and drier

47 The First Hominids Sahelanthropus tchadensis arose 6-7 million years ago Sahelanthropus tchadensis arose 6-7 million years ago Bipedal australopiths evolved during Miocene into Pliocene Bipedal australopiths evolved during Miocene into Pliocene Exact relationships are not known Exact relationships are not known A. anamensis A. afarensis A. africanus A. garhi A. boisei A. robustus

48 Homo Habilis 1.9-1.6 million years ago May have been the first member of genus May have been the first member of genus Lived in woodlands of eastern and southern Africa Lived in woodlands of eastern and southern Africa H. habilis Figure 26.31 Page 468 Do not post on Internet

49 Homo erectus 2 million-53,000? years ago Evolved in Africa Evolved in Africa Migrated into Europe and Asia Migrated into Europe and Asia Larger brain than H. habilis Larger brain than H. habilis Creative toolmaker Creative toolmaker Built fires and used furs for clothing Built fires and used furs for clothing

50 Homo sapiens Modern man evolved by 100,000 years ago Modern man evolved by 100,000 years ago Compared to Homo erectus: Compared to Homo erectus: –Smaller teeth and jaws –Chin –Smaller facial bones –Larger-volume brain case

51 Neanderthals Early humans that lived in Europe and Near East Early humans that lived in Europe and Near East Massively built, with large brains Massively built, with large brains Disappeared when H. sapiens appeared Disappeared when H. sapiens appeared DNA evidence suggests that they did not contribute to modern European populations DNA evidence suggests that they did not contribute to modern European populations

52 Earliest Fossils Are African Earliest Fossils Are African Africa appears to be the cradle of human evolution Africa appears to be the cradle of human evolution No human fossils older than 2 million years exist anywhere but Africa No human fossils older than 2 million years exist anywhere but Africa Homo erectus left Africa in waves from 2 million to 500,000 years ago Homo erectus left Africa in waves from 2 million to 500,000 years ago

53 Where Did H. sapiens Arise? Two hypotheses: Two hypotheses: –Multiregional model –African emergence model Both attempt to address biochemical and fossil evidence Both attempt to address biochemical and fossil evidence

54 Multiregional Model Argues that H. erectus migrated to many locations by about 1 million years ago Argues that H. erectus migrated to many locations by about 1 million years ago Geographically separated populations gave rise to phenotypically different races of H. sapiens in different locations Geographically separated populations gave rise to phenotypically different races of H. sapiens in different locations Gene flow prevented races from becoming species Gene flow prevented races from becoming species

55 African Emergence Model Argues that H. sapiens arose in sub- Saharan Africa Argues that H. sapiens arose in sub- Saharan Africa H. sapiens migrated out of Africa and into regions where H. erectus had preceded them H. sapiens migrated out of Africa and into regions where H. erectus had preceded them Only after leaving Africa did phenotypic differences arise Only after leaving Africa did phenotypic differences arise

56 Genetic Distance Data NEW GUINEA, AUSTRALIA PACIFIC ISLANDS SOUTHEAST ASIA ARCTIC, NORTHEAST ASIA NORTH, SOUTH AMERICA NORTHEAST ASIA EUROPE, MIDDLE EAST AFRICA 0.20.10 Genetic distance (percent) Figure 26.37 Page 471


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