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Animal Evolution – The Chordates

Animal Evolution – The Chordates. Chapter 26 Part 2. 26.10 Birds—The Feathered Ones. Birds are the only animals with feathers Descendants of flying dinosaurs in which scales became modified as feathers Long feathers are adapted for flight Downy feathers provide insulation.

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Animal Evolution – The Chordates

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  1. Animal Evolution – The Chordates Chapter 26 Part 2

  2. 26.10 Birds—The Feathered Ones • Birds are the only animals with feathers • Descendants of flying dinosaurs in which scales became modified as feathers • Long feathers are adapted for flight • Downy feathers provide insulation

  3. Dinosaurs and Feathers

  4. Fig. 26-20a, p. 446

  5. Fig. 26-20b, p. 446

  6. Fig. 26-20c, p. 446

  7. Fig. 26-20d, p. 446

  8. Bird Adaptations • Bird characteristics • Eggs • No teeth • Produce body heat (endotherms) • Lightweight skeleton, strong muscles, and efficient circulation and respiration for flight • Wings with flight feathers

  9. A Bird Egg

  10. yolk sac embryo amnion chorion allantois hardened shell albumin (“egg white”) Fig. 26-21, p. 446

  11. Animation: Amniote egg

  12. Adaptations for Flight

  13. Fig. 26-22a, p. 447

  14. Fig. 26-22b, p. 447

  15. Fig. 26-22c, p. 447

  16. skull radius internal structure of bird limb bones pectoral girdle ulna humerus pelvic girdle sternum (breastbone) two main flight muscles attached to keel of sternum Fig. 26-22c, p. 447

  17. Animation: Avian bone and muscle structure

  18. 26.11 The Rise of Mammals • Mammals are animals that nourish young with milk and have hair or fur; four kinds of teeth allow them to eat many kinds of food

  19. Fig. 26-23a, p. 448

  20. Fig. 26-23b, p. 448

  21. incisors molars premolars canines Fig. 26-23b, p. 448

  22. Mammalian Evolution • Monotremes (egg-laying mammals) and marsupials (pouched mammals) evolved during the Jurassic • Placental mammals (mammals with a placenta that exchanges materials between the mother and embryo inside the body) evolved later

  23. Distribution of Mammalian Lineages • Mammals underwent adaptive radiation after dinosaurs died out • Continental movements influenced distribution • Some mammals show morphological convergence

  24. Distribution of Mammalian Lineages

  25. southern land mass Pangea A About 150 million years ago, during the Jurassic, the first monotremes and marsupials evolved and migrated through the supercontinent Pangea. B Between 130 and 85 million years ago, during the Cretaceous, placental mammals arose and began to spread. Monotremes and marsupials that lived on the southern land mass evolved in isolation from placental mammals. C Starting about 65 million ago, mammals expanded in range and diversity. Marsupials and early placental mammals displaced monotremes in South America. D About 5 million years ago, in the Pliocene, advanced placental mammals invaded South America. They drove most marsupials and the early placental species to extinction. Fig. 26-24, p. 448

  26. Paleocene Mammals

  27. The Largest Land Mammal • Giraffe rhinoceros (Indricotherium) lived in Asia during the Oligocene

  28. Convergent Evolution

  29. 26.7-26.11 Key Concepts The Amniotes • Amniotes—reptiles, birds, and mammals—have waterproof skin and eggs, highly efficient kidneys, and other traits that adapt them to a life that is typically lived entirely on land • Reptiles and birds belong to one amniote lineage, and mammals to another

  30. 26.12 Modern Mammalian Diversity • Egg-laying monotremes lay leathery eggs • Spiny anteaters, platypus • Pouched marsupials develop in a pouch • Kangaroos, koala, opossum, Tasmanian devil • Placental mammals include most living mammals • Rodents and bats are the most diverse groups

  31. Monotremes: Platypus

  32. Marsupials

  33. Placental Mammals: The Placenta

  34. placenta uterus embryo Fig. 26-30a, p. 451

  35. Placental Mammals

  36. 26.13 From Early Primates to Hominids • Primates: Mammalian subgroup including humans, apes, monkeys, and prosimians • Anthropoids: Humans, apes, and monkeys • Hominids: Humans and apes

  37. Primate Classification

  38. Primates

  39. Adaptations for Walking • Monkey, gorilla, and human

  40. Overview of Key Trends • Five trends led to uniquely human traits • Enhanced daytime vision (binocular vision) • Upright (bipedal) walking • Better grips (power grip and precision grip) • Modified jaws and teeth (omnivorous diet) • Brain, behavior, and culture (transmission of learned behavior between individuals and generations)

  41. Adaptations for Walking • Location of the foramen magnum in four-legged and upright walkers

  42. a Hole at back of skull; the backbone is habitually parallel with ground or a plant stem b Hole close to center of base of skull; the backbone is habitually perpendicular to ground Fig. 26-32, p. 453

  43. Better Grips • Power grip (prehensile movement) and precision grip (opposable movement)

  44. Origins and Early Divergences • 65 mya: First primates (shrewlike) • 36 mya: Tree dwelling anthropoids • 23-18 mya: First hominoids (early apes) • 6 mya: Hominids

  45. Early Primates

  46. Fig. 26-33a, p. 453

  47. Fig. 26-33 (b-d), p. 453

  48. 26.14 Emergence of Early Humans • 6-8 mya: Early hominids from Africa

  49. a b c d e Sahelanthropus tchadensis 6 million years ago Australopithecus africanus 3.2–2.3 million years ago Paranthropus boisei 2.3–1.2 million years ago Homo habilis 1.9–1.6 million years ago Homo erectus 1.9 million to 53,000 years ago Fig. 26-34, p. 454

  50. Australopiths • The first bipedal hominids (Australopithacus) were probably human ancestors

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