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Chapter 34

Chapter 34. Vertebrates. The animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone Vertebrates are a subphylum of the phylum chordata. 1. What are the four characteristics of chordates?.

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Chapter 34

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  1. Chapter 34 Vertebrates

  2. The animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone • Vertebrates are a subphylum of the phylum chordata

  3. 1. What are the four characteristics of chordates? • Notochord – flexible rod between digestive tube and nerve cord (skeletal support) • Dorsal, hollow nerve cord – develops into CNS • Pharyngeal slits/clefts – become feeding structures, gills, or ear/neck parts • Muscular, post-anal tail – propulsion or balance

  4. Fig. 34-3 Dorsal, hollow nerve cord Muscle segments Notochord Mouth Anus Pharyngeal slits or clefts Muscular, post-anal tail

  5. Fig. 34-4 Cirri 2 cm Mouth Pharyngeal slits Atrium Notochord Digestive tract Atriopore Dorsal, hollow nerve cord Segmental muscles Anus Tail Lancelets

  6. Fig. 34-5 Incurrent siphon to mouth Water flow Notochord Dorsal, hollow nerve cord Excurrent siphon Tail Excurrent siphon Excurrent siphon Atrium Muscle segments Incurrent siphon Pharynx with slits Intestine Anus Stomach Intestine Tunic Atrium Esophagus Pharynx with slits Stomach An adult tunicate A tunicate larva Tunicates

  7. Fig. 34-9 Slime glands Hagfish • Craniates share some characteristics: a skull, brain, eyes, and other sensory organs

  8. Lampreys • Lampreys (Petromyzontida) represent the oldest living lineage of vertebrates • They are jawless vertebrates inhabiting various marine and freshwater habitats • They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

  9. Fig. 34-14 Gnathostomes – jawed vertebrates

  10. Fig. 34-15 • Chondrichthyans have a skeleton composed primarily of cartilage Pelvic fins Pectoral fins (a) Blacktip reef shark (Carcharhinus melanopterus) (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei)

  11. Fig. 34-17 • osteichthyans have a bony endoskeleton (a) Yellowfin tuna (Thunnus albacares) (b) Clownfish (Amphiprion ocellaris) (d) Fine-spotted moray eel (Gymnothorax dovii) (c) Sea horse (Hippocampus      ramulosus)

  12. 2. In the evolution of vertebrates, identify the significance of being a tetrapod. • Tetrapodshave some specific adaptations: • Four limbs, and feet with digits • Support out of water • Ears for detecting airborne sounds

  13. Fig. 34-21 Amphibians (a) Order Urodela (b) Order Anura (c) Order Apoda

  14. Fig. 34-22 (a) Tadpole (b) During metamorphosis (c) Mating adults

  15. 3. What is the significance of the amniotic egg and amniotes? • Amniotes are a group of tetrapods whose living members are the reptiles, including birds, and mammals • 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

  16. Fig. 34-25 Chorion Allantois Yolk sac Amnion Embryo Amniotic cavity with amniotic fluid Yolk (nutrients) Albumen Shell

  17. Keeps embryo from drying out • Exchanges gases and wastes • Absorbs shock • Amniotes have other terrestrial adaptations, such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs

  18. Fig. 34-27 Reptiles (a) Tuatara (Sphenodon punctatus) (b) Australian thorny devil lizard (Moloch horridus) (c) Wagler’s pit viper (Tropidolaemus wagleri) (d)Eastern box turtle (Terrapenecarolinacarolina) (e) American alligator (Alligator mississippiensis)

  19. Fig. 34-30 • Birds – wings, no teeth or bladder (a) Emu (b) Mallards (c) Laysan albatrosses (d) Barn swallows

  20. Derived Characters of Mammals • Mammals have • Mammary glands, which produce milk • Hair • A larger brain than other vertebrates of equivalent size • Differentiated teeth

  21. 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

  22. Fig. 34-32 • Monotremes - egg-laying mammals consisting of echidnas and the platypus

  23. Fig. 34-33 • Marsupials (opossums, kangaroos, koalas) • embryo develops within a placenta in the mother’s uterus, completes its development while nursing in a maternal pouch (a) A young brushtail possum (b) Long-nosed bandicoot

  24. Eutherians (Placental Mammals) • eutherianscomplete their embryonic development within a uterus, joined to the mother by the placenta

  25. Primates • The mammalian order Primates includes lemurs, tarsiers, monkeys, and apes • Humans are members of the ape group • Most primates have hands and feet adapted for grasping

  26. 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)

  27. Derived Characters of Humans • A number of characters distinguish humans from other apes: • Upright posture and bipedal locomotion • Larger brains • Language capabilities and symbolic thought • The manufacture and use of complex tools • Shortened jaw • Shorter digestive tract

  28. 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

  29. Hominins originated in Africa about 6–7 million years ago • Early hominins had a small brain but probably walked upright

  30. Two common misconceptions about early hominins: • Thinking of them as chimpanzees • Imagining human evolution as a ladder leading directly to Homo sapiens

  31. Australopiths • Some species walked fully erect • “Robust” australopiths had sturdy skulls and powerful jaws • “Gracile” australopiths were more slender and had lighter jaws

  32. 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”

  33. Homo ergaster was the first fully bipedal, large-brained hominid • The species existed between 1.9 and 1.5 million years ago • Homo ergastershows a significant decrease in sexual dimorphism (a size difference between sexes) compared with its ancestors

  34. Homo erectus originated in Africa by 1.8 million years ago • It was the first hominin to leave Africa

  35. Neanderthals • Neanderthals, Homo neanderthalensis, lived in Europe and the Near East from 200,000 to 28,000 years ago • They were thick-boned with a larger brain, they buried their dead, and they made hunting tools

  36. Homo Sapiens • Homo sapiens appeared in Africa by 195,000 years ago • All living humans are descended from these African ancestors

  37. The oldest fossils of Homo sapiens outside Africa date back about 115,000 years and are from the Middle East • Humans first arrived in the New World sometime before 15,000 years ago • In 2004, 18,000 year old fossils were found in Indonesia, and a new small hominin was named: Homo floresiensis

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